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US20250320683A1 - Steel Reinforced Trench Fill for Ground Stabilization - Google Patents

Steel Reinforced Trench Fill for Ground Stabilization

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Publication number
US20250320683A1
US20250320683A1 US19/086,070 US202519086070A US2025320683A1 US 20250320683 A1 US20250320683 A1 US 20250320683A1 US 202519086070 A US202519086070 A US 202519086070A US 2025320683 A1 US2025320683 A1 US 2025320683A1
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Prior art keywords
trench
fill
trenches
rebar
soil
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Pending
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US19/086,070
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Theo Robert Seeley
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Individual
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Individual
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Publication date
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Priority to US19/086,070 priority Critical patent/US20250320683A1/en
Publication of US20250320683A1 publication Critical patent/US20250320683A1/en
Pending legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D17/00—Excavations; Bordering of excavations; Making embankments
    • E02D17/06—Foundation trenches ditches or narrow shafts
    • E02D17/08—Bordering or stiffening the sides of ditches trenches or narrow shafts for foundations
    • E02D17/083—Shoring struts

Definitions

  • the second provisional patent application uses similar steel reinforced trenches for general ground stabilization. These trenches could be used for a new or existing slope where additional stabilizing elements are desired. These trenches would be similar in construction, but they would be buried below the surface and discontinuous to prevent groundwater blockage. Also, they could be excavated in “T”, “L”, or “I” shape depending upon the soil conditions. The shapes shown on the enclosed figures are only intended to demonstrate the concept. Given the unlimited variations that trenches can take, this patent claims that any trench designed for ground stabilization and uses modified rebar as described herein is covered by this patent application. This patent is not limited to any or by any particular grouting method including the possibility of not grouting or only partially grouting the trench backfill.
  • This disclosure relates generally but not by way of limitation to the construction of in-situ ground improvement for either new compacted fill soil, existing fill soil, naturally occurring soil and rock formations and support of retaining walls by improving the stability of said formations and simultaneously acting as tie back anchors.
  • the methods for building new fill involve either building retaining walls or stable slopes at the perimeter of the new fill.
  • the method presented herein will work to stabilize either new fill or existing ground using known engineering principals and construction elements.
  • New fill is commonly stabilized by placing stabilizing elements in the fill as the layers of fill are placed and compacted.
  • This method is known as Mechanically Stabilized Earth or MSE.
  • MSE Mechanically Stabilized Earth
  • These are very effective methods of stabilizing new compacted granular fill. That method relies on developing friction between the stabilizing elements and the granular fill. It also requires some form of non-erosive wall face such as concrete interlocking segments. Therefore, it is limited to sand and sandy gravelly soils.
  • MSE cannot work with an exposed slope due to the erosive nature of granular soil.
  • the method presented in this patent application will work with a wider range of soils because it relies on active and passive pressure as well as friction. Therefore, this system will work with a wider range of soils and it is possible to construct this system with a stable nonerosive perimeter slope face.
  • Tie back anchors for retaining walls typically use a dead man system as the earth anchor.
  • the dead man anchor is typically a concrete block located beyond the active wedge or any calculated failure plane and attached to the wall by way of a small cable or tie rod. The cable or rod is then attached to the back of the wall.
  • New fill is commonly stabilized by placing stabilizing elements in the fill as the layers of fill are placed and compacted.
  • This method is known as Mechanically Stabilized Earth or MSE.
  • MSE Mechanically Stabilized Earth
  • Ground improvement of existing soil and rock is typically by constructing rows of steel reinforced concrete piles commonly known as soldier piles. To provide stability they need to be set deep enough that they are founded in stable material. Constructing these large diameter piles requires large equipment and significant time for the concrete to gain sufficient strength to improve the stability of the soil mass.
  • This patent provides a method for building a safe stable soil fill by constructing grouted steel reinforced discontinuous trenches within soil.
  • the purpose of these trenches is to provide a grouted rock stiffening system to improve the overall strength of existing soil or new compacted fill without creating an impermeable groundwater barrier.
  • the method of trench construction is easy and quick and will not impede the construction process of building a new compacted soil fill.
  • This method of ground stabilization is similar to a known landslide stabilization system that uses drilled cast in place steel reinforced concrete piles that penetrate the failure plane of the landslide. That is a method of pinning the unstable landslide mass to the stable material below the failure plane where, these piles are known as soldier piles.
  • the soldier piles are typically constructed in rows with a designed open space between the piles.
  • the process proposed herein is similar to the soldier pile method of inserting rows of strong piles within an unstable mass to improve its stability.
  • the process proposed would accomplish the same improvement using smaller equipment such as a backhoe and in place of soldier piles the stabilization would be provided by steel reinforced grouted trenches.
  • the trenches would be founded horizontally beyond any failure plane as opposed to the piles extending below the failure plane.
  • the unstable mass is that portion of the fill near the edge of the fill. If there is not sufficient space for a long gentle slope, then the edge needs to be constructed with steep or vertical edges.
  • steep edges of a new soil fill require very large strong retaining walls to support the loads created by gravity acting on the fill soil at the edge of the fill. What is proposed herein is that these large forces can be counteracted by installing hardened discontinuous trenches during construction. These trenches will only occupy a small percentage of the fill volume but increase the overall strength of the fill mass, thus making the new fill stable.
  • compacted soil typically has a saturated unconfined shear strength on the order of 2 to 4 Pounds Per Square Inch (PSI).
  • PSI Pounds Per Square Inch
  • a trench filled with rock and or inert debris such as broken pieces of concrete, and gravel and then grouted in place would have a minimum unconfined shear strength on the order of 200 to 400 PSI. This results in a hardened zone that when properly located will cross and provide support to a potential failure plane.
  • the trench fill includes steel rebars. These steel rebars will be precast in concrete cover where the concrete provides minimum corrosion cover and has an undulating shape.
  • This method of modifying the rebar prior to construction allows the rebar to be structurally tied to the rock fill.
  • the result of placing a designed number of hardened trenches within a new compacted fill is to increase the overall strength of the fill. Then the compacted fill will have sufficient strength to resist the gravitational force pushing the fill to failure at the edge. The gravitational force results in active pressure on a hardened trench. That active pressure is transmitted through the stronger trench to stable soil which provides support in the form of passive pressure or friction. The final result is a stable over steepened or vertical slope at the edge of the new compacted fill.
  • One advantage to this system is the grouting can be delayed until a large number of trenches are ready to be grouted.
  • the grouting process is more efficient when a large number of trenches are grouted at one time.
  • the final strength of the trench is desired during construction, then once the trench fill is complete it can be grouted immediately.
  • chemical grout has a set time is significantly shorter than cure time for Portland cement. Therefore, if quick setting grout is used then the structural benefit of having the steel and rock filled trench in the soil would be almost immediate.
  • This patent provides a ground stabilization method that uses common building materials to construct stabilization trenches in the ground where improved stability is desired.
  • This system will overcome some of the common limitations of existing ground improvement systems such as only working with granular soil or needing large equipment and long-time delay for the stabilization to take effect.
  • This system would require excavating into new compacted fill or existing soil to create a series of discontinuous trenches at designed elevations and locations.
  • the trenches would be filled with granular fill, and/or rock, modified rebar, and a grouting system as they are being constructed.
  • the grouting system shown on the Figures uses a manifold system to improve the grout distribution. It should be noted that the same grouting could be accomplished using multiple vertical injection pipes if that would provide the desired improvement.
  • the primary goal is to fill the naturally occurring voids when making granular deposits in the trench. If needed, each trench could be grouted as soon as the backfilling process is complete, and before the next trench is excavated. This would allow the improvement process to develop as the work is being done.
  • the trench fill may be impermeable to ground water. This can become a problem for long or deep trenches filled with material less permeable than the surrounding soil. This is known as a groundwater barrier. Therefore, this trench design is intended to be discontinuous to ensure that the natural flow of groundwater is not impeded. Continuous trenches over long distances could be grouted provided the design includes provisions to allow for ground water to flow through the barrier or account for the change in ground water hydrology.
  • compacted soil typically has a saturated unconfined shear strength on the order of 2 to 4 Pounds Per Square Inch (PSI).
  • PSI Pounds Per Square Inch
  • a trench filled with rock and/or inert debris such as broken pieces of concrete, and gravel and then grouted in place would have a minimum unconfined shear strength on the order of 200 to 400 PSI.
  • the trench fill needs to include steel rebars.
  • steel rebars To prevent the corrosion of the steel rebars they will be precast in concrete, where the concrete provides minimum corrosion cover and has an undulating shape.
  • This method of modifying the rebar prior to construction allows the rebar to be structurally tied to the rock fill.
  • the result of placing a designed number of hardened trenches within a new compacted fill is to increase the overall strength of the fill, and thus improve the global and surficial stability.
  • the compacted fill will have sufficient strength to resist the gravitational force pushing the fill to failure at the edge.
  • the gravitational force results in active pressure on one end of the hardened trench. That active pressure is transmitted through the stronger steel reinforced trench to stable soil which provides support in the form of passive pressure or friction.
  • the final result is a stable over steepened or vertical slope at the edge of the new compacted fill.
  • the above nine steps may look long or involved but if a backhoe or similar equipment is used along with a well-organized small crew, it could be completed in a relatively short period of time.
  • the various parts do not need to be placed in a very precise manner for the trench to have a shear strength at least 100 times the strength of the compacted fill.
  • the transfer load from the rebar to the rock fill and visa versa will occur. This load transfer occurs directly between the rock and the concrete cover on the rebar.
  • the purpose of the grout is not to add strength to the matrix but to lock the various parts in place such that the rocks and the modified rebar will not shift or move. In addition to locking the trench fill in place it is possible that the grout will expand into the fill helping to tie the trench to the compacted fill.
  • FIG. 1 Presents a perspective view of the initial stage of the construction of a fill that will be supported by a retaining wall that will be assembled using prefabricated wall segments installed in a series of slot cuts in the temporary false slope. Also shown are the locations of two cross sections shown as FIG. 1 A and FIG. 1 B .
  • FIG. 1 A Shows a typical cross section of the new fill placed upon the existing soil. This section shows the fill placed against an existing soil slope.
  • FIG. 1 B This figure is drawn through one of the slot cuts and the trench that will extend beyond and behind the proposed wall face.
  • FIG. 2 A perspective view of a completed retaining wall showing several segments. One of the segments is presented in a cut away view which is enlarged in FIG. 3 .
  • FIG. 3 is a perspective enlargement of the wall segment from FIG. 2 and the cut away section where the supporting trench system modified rebar is attached to the wall segment. Within the trench the modified rebar is shown with the undulating concrete cover. Under the top rebar is the grout distribution system.
  • FIG. 3 also shows the alignment of section drawings for FIG. 4 A , FIG. 4 B , FIG. 5 A , and FIG. 5 B .
  • FIG. 4 A This shows a partially filled trench where a bed of rock and gravel has been placed in the bottom of the trench up to the elevation of the lower modified rebar. At the back of the trench is the vertical cut that was made into the initial compacted fill.
  • FIG. 4 B The trench has now been filled to match the top of the existing grade of the initial compacted fill. This shows two modified rebar with the upper modified rebar angling down to be anchored deeper into the rock fill, and closer to the grout.
  • FIG. 5 A is a cross section of the trench partially filled with rock, modified rebar, and the grouting system.
  • the void space between the rocks is where the grout will flow to solidify the entire mass.
  • FIG. 5 B shows the cross section of a completed support trench that has been grouted.
  • the section drawing shows two modified rebar a grout distribution system. The grout flowing between the rock through the interconnected void spaces
  • FIG. 6 shows the back of a wall segment with unmodified portion of the rebar inserted into the space within the wall opening and the opening can be filled with concrete to make the modified rebar a permanent part of the wall segment.
  • FIG. 7 shows an alternate method of modifying rebar to increase the rebar ability to transfer load to or from the surrounding material.
  • a section of sheet metal 16 has been bent and has holes in each folded such that the rebar 1 can be inserted through the hole to join the two items together.
  • FIG. 8 presents an alternate design for modifying rebar 2 such that the rebar has a minimum concrete cover to protect the steel from corrosion. Depending upon the anticipated loading and the size of the enlarged washer shape may need additional rebar.
  • FIG. 9 presents a longitudinal section through a concrete covered modified rebar. This drawing shows the different variables that would need to be addressed for every project to have the optimum effectiveness for those projects loads and materials. It also includes two sections for different possible designs.
  • FIG. 10 A shows an alternative cross section of the washer described and shown on FIG. 8 .
  • FIG. 10 A is a hexagonal shape with the primary rebar in the center and a secondary rebar within the hexagon.
  • FIG. 10 B is a cross section of the washer shape presented in perspective in FIG. 8 .
  • FIG. 11 This view provides a cutaway view showing the stabilizing trenches behind a retaining wall with additional “T” shaped trenches under the sloping fill behind the wall.
  • FIG. 12 Presents a section through a partially completed wall with fill compacted up to the elevation of the lower wall segment.
  • the wall is supported by a trench that was excavated into the partially completed fill.
  • FIG. 13 Presents the same wall and section cut view as in FIG. 12 but now the section is completed.
  • This section shows how a second trench has been installed above and behind the first trench. The primary difference between the two trenches is modified rebar is completely within the trench for the purposes of providing tensile reinforcement to the trench fill.
  • FIG. 1 perspective view of a retaining wall with a series of “T” and “L” shaped trenches that are discontinuous and staggered throughout the fill.
  • FIG. 14 Is a perspective view of a completed wall with trenches staggered both horizontally and vertically.
  • a reinforced multiple trench system would work to provide stabilization for new fill or existing soil.
  • FIG. 15 Shows a section view of a high wall stabilized by multiple discontinuous trenches completed and grouted. Also shown are two possible failure surfaces where the chosen surfaces encounter the trenches which have a shear strength on the order of 100 times the strength of the compacted fill. The second potential failure is shown taking a longer and difficult path to avoid the higher strength trenches.
  • the plans need to identify specific locations, elevation, shapes of the trenches, and the material to be used in the trench backfill.
  • the findings of the design analyses and engineering requirements need to be incorporated into the plans.
  • Typical settlement monuments should be included in the fill to track the movement of the fill as more fill soil is placed and compacted. It should be noted that movement of fill soil during the placement of additional fill is normal. What needs to be tracked is making sure the movement is within the anticipated range of movement. Another test should be made to track the air pressure inside the trench when the trench is grouted. This along with the volume of grout injected would provide confidence that the grouting operation was complete and successful.
  • FIG. 1 A first figure.
  • FIG. 1 shows the location of two typical section views labeled FIG. 1 A and FIG. 1 B .
  • FIG. 1 A A first figure.
  • This figure shows a typical cross section of the new fill 5 placed upon the existing soil 4 .
  • This section shows the fill placed against an existing soil slope 4 .
  • Fill 5 has a slope that extends beyond the alignment 24 of the proposed retaining wall to ensure temporary stability.
  • Each trench 121 has a grout injection tube 11 that extends down into the trench 121 fill.
  • One of the segments is presented in a cut away view which is enlarged in FIG. 3 . The cut away exposes the internal section of the wall segment 14 and the support system located inside the trench 121 along with the grout system. Also shown are the weep holes 13 in the base of the wall segments 14 . These are located just above the concrete channel footing 15 . Just in front of footing 15 and behind the fill is the existing or native soil 4 .
  • FIG. 3 is a perspective enlargement of the wall segment 14 from FIG. 2 and the cut away section where the supporting trench 121 system intersects the wall segment 14 .
  • the wall segments 14 are shown with the weep holes 13 and the concrete footing 15 .
  • Within the cut away the original compacted fill 5 is exposed behind the wall and next to the trench 121 .
  • Within the trench the modified rebar 2 is shown with the undulating concrete cover 2 inside the trench.
  • the same rebar 1 is shown without concrete cover 2 as it enters the formed pocket 22 in the back of the wall segment 14 .
  • the pocket will be filled with concrete grout which will also cover the exposed portion of rebar 1 .
  • the rebar 1 with its modified concrete covered section 2 is the top rebar.
  • the grout distribution pipe 9 Under the top rebar is the grout distribution pipe 9 which is surrounded by coarse sand 6 all within the protective geotextile wrap 10 . This prevents pipe 9 from being damaged by the rock or inert concrete debris 8 that is placed on top and on the sides of the grout pipe 9 . Along with rock fill 8 the larger voids are filled with gravel 7 .
  • the grout delivery pipe 11 vertically rises out of the filter cloth 10 to an elevation above the trench 121 where it can be attached to a grout generating system which is not shown.
  • FIG. 3 shows the alignment of section drawings for FIG. 4 A , FIG. 4 B , FIG. 5 A , and FIG. 5 B .
  • the FIGS. 4 A and 4 B are longitudinal sections of the trenches.
  • FIG. 4 A being made when the trench 21 is only partially filled and
  • FIG. 4 B shows the trench 121 filled but not grouted.
  • FIG. 5 A shows a cross section of the trench 21 partially filled and
  • FIG. 5 B presents a cross section of the trench 121 completed and grouted.
  • FIG. 4 A A first figure.
  • a zone of sand 6 has been compacted in the front of the trench 21 between the rock 8 and where the back side of the wall segment 14 will be placed on top of concrete footing.
  • Above the footing 15 is the rebar 1 which is the same rebar shown as a dashed rebar within the concrete cover 2 .
  • the modified concrete covered rebar 2 has been placed on top of rock 8 and gravel 7 fill that has been placed at that time.
  • At the back of the trench 21 is the vertical cut that was made into the initial compacted fill 5 .
  • the trench 21 has now been filled to become trench 121 as it now matches the top of the existing grade of the initial compacted fill 5 .
  • This design shows two modified rebar 2 , however what is claimed is that each project will require an individual design which may require more or fewer modified rebar, or wall segments 14 supported by more than one supporting trench 121 .
  • the upper modified rebar 2 is shown angling down to be anchored deeper into the rock 8 fill, and closer to the grout distribution pipe 9 .
  • Between the two modified rebars 2 is the grout distribution pipe 9 surrounded by the sand 6 and the geotechnical cloth 10 wrapped around to protect the pipe 9 from damage during construction.
  • the grout injection pipe 11 rises out of the trench fill starting from a “T” connection with the distribution pipe 9 .
  • the rock 8 fill is capped with the same compacted fill soil 5 used for the initial compacted soil 5 fill.
  • a zone of sand 6 behind the wall segment 14 .
  • the wall segment 14 which is supported by the concrete footing 15 and held in place by the two rebars 1 inserted into the back of the wall segment 14 .
  • With the weight of the rock 8 on and around the two modified rebar 2 it is possible that the wall segment 14 is temporarily stable and although it is ready for grout 19 to be injected into the trench the injection of the grout 19 could wait until all, or a large number of segments 14 are ready for grouting. This flexibility in timing of injecting grout 19 could improve the economy of the overall project.
  • FIG. 5 A A first figure.
  • FIG. 5 A is a cross section of the trench 21 partially filled with rock 8 , modified rebar 2 and the grouting system.
  • the grouting system consists of the central grout distribution pipe 9 surrounded by sand 6 wrapped in geotechnical filter cloth 10 . Also shown is the grout injection pipe 11 connected to grout distribution pipe 9 .
  • the void space 20 between the rock 8 is where the grout will flow into the fill to solidify the entire mass once the trench fill is complete.
  • FIG. 5 B shows a cross section of a completed support trench 121 that has been grouted.
  • the section drawing shows two modified rebar 2 and one grout distribution system where the grout 19 has flowed out between the grains of sand 6 and through the geotechnical filter cloth 10 and out into the void space 20 .
  • the grout 19 may flow beyond the trench wall into the compacted fill soil 5 . This would tie the trench rock 8 fill to the compacted soil fill 5 beyond the limit of the initial trench 21 excavation.
  • At the top of the trench is a layer of the fill soil 5 that has been recompacted over the rock 8 fill prior to grouting to help keep the grout 19 flowing between the rock 8 through the interconnected void space 20 .
  • With grout 19 surrounding the rocks 8 the rocks 8 are now locked in place such that modified rebars 2 are also locked in place. This results in the wall segment 14 becoming stable because it is attached to the modified rebar 2 .
  • FIG. 6 shows the back side of a possible design for wall segments 14 .
  • the drawing shows a wall segment 14 with a rectangular indentation 22 with horizontal rebar 1 that cross the opening such that the unmodified rebar 1 section can be inserted into the space between the concrete of the segment 14 and the horizontal rebar 1 .
  • a cover can be placed over the opening and the opening can be filled with concrete to make the modified rebar 2 a permanent part of the wall segment 14 .
  • FIG. 7 shows an alternate method of modifying rebar 1 to increase the rebar 1 ability to transfer load to or from the surrounding material.
  • a section of sheet metal 16 has been bent and has holes in each folded such that the rebar 1 can be inserted through the hole to join the two items together.
  • Another method would be to place grout 19 or cement 3 around the rebar 2 after the two parts are assembled. It is possible to use this design for the trench stabilization system described herein.
  • FIG. 8 presents another alternate design for creating modifying rebar 2 such that the rebar 1 has a minimum concrete 2 cover to protect the steel from corrosion. Then spaced at designed intervals are washer shaped enlarged sections. The purpose of the enlarged sections is to improve the load transfer from surrounding material to the rebar 1 that runs through the center portion of the concrete to form a modified rebar 2 system. Depending upon the anticipated loading and the size of the enlarged washer shaped section the enlarged section may need additional rebar 1 formed into a circular shape to reinforce that portion of the modification of the center rebar 1 as shown for one of the washers presented on this figure. It is possible to use this design for the trench stabilization system described herein.
  • FIG. 9 presents a longitudinal section through a concrete covered modified rebar 2 .
  • the purpose of this drawing is to show the different variables that would need to be addressed for every project to have the optimum shape. These variables would apply regardless of the cross-sectional shape.
  • variable “D” is the minimum distance to provide safe cover for the rebar 1 to ensure that the rebars 1 have proper corrosion protection.
  • Variable “A” is the angle of the slope between the minimum cover cylinder 17 alignment and the slope up to the outer portion of the undulating concrete cover. Variable “A” could range from 10 to 90 degrees.
  • Variable “F” is the angle of the slope between the minimum cover cylinder 17 alignment and the slope down from the outer portion of the undulating concrete cover. Variable “F” could range from 10 to 90 degrees.
  • FIG. 10 A is cross-section through a typical ridge.
  • FIG. 10 B is also a cross-section through another design of a ridge.
  • FIG. 10 A A first figure.
  • This view shows an alternative cross section of the washer shaped enlarged section described and shown on FIG. 8 .
  • FIG. 10 A a hexagonal shape is presented, however this is only to demonstrate that a geometric shape could be used in place of a round shaped washer.
  • This view shows the primary rebar 1 in the center and a secondary rebar 1 in a circular shape to reinforce the hexagon.
  • FIG. 10 B is a cross section of the washer shape presented in perspective in FIG. 8 . This view shows the primary rebar 1 in the center and a secondary rebar 1 in a circular shape to reinforce the circle.
  • This view provides a cutaway view showing the stabilizing trench 121 behind a retaining wall 124 and under the sloping compacted fill 5 behind the wall.
  • the trench directly behind the wall has modified rebars 2 that are attached to the wall at slot 22 . Inside slot 22 is the rebar 1 .
  • This trench acts as a tie back for stabilizing the wall 124 .
  • Above and behind the wall are two “T” shaped stabilizing trenches 121 that have sufficient space between them to allow for drainage. It should be noted that the trenches 121 in this view only show the outline of the trench and the modified rebar 2 .
  • the completed trenches would include the rock and gravel fill that has been grouted in place and surrounding the modified steel rebar 2 .
  • the scale of this Figure does not allow for these details to be shown but they would be the same as presented on FIG. 5 B .
  • the grouted fill will obscure view of the modified steel rebar 2 .
  • the “T” shape is intended to provide stabilization for the fill located behind the trench that runs up the slope.
  • the modified rebars 2 tie the trench fill together and tie the front trench 121 to the back section of the trench 121 for stability.
  • the lower section of wall 124 is supported horizontally by a trench that was excavated into the partially completed fill soil 5 .
  • the section is drawn through the middle of the trench exposing the modified rebar 2 and the grout system.
  • the grouting system consists of the grout injection pipe 11 going into the geotechnical filter cloth 10 to the grout distribution pipe 9 surrounded by sand 6 wrapped in geotechnical filter cloth 10 .
  • the section cuts through the subdrain system including the sand 6 pocket and the drainpipe 13 .
  • the wall segment 124 is supported by footing 15 founded in the existing soil 4 .
  • the top of wall segment 124 has a slot 30 for the next segment to fit into.
  • FIG. 12 This shows the same view as FIG. 12 except the next wall 124 segment has been added along with new compacted soil 5 fill and an additional trench of the same design and construction.
  • the trenches are staggered both horizontally and vertically to ensure that drainage is not blocked. Both trenches have the same grouting system.
  • the grouting system consists of the grout injection pipe 11 going into the geotechnical filter cloth 10 to the grout distribution pipe 9 surrounded by sand 6 wrapped in geotechnical filter cloth 10 .
  • the lower trench is shown to be grouted with grout 19 filling the void space around the rock 8 and the modified rebar 2 .
  • the upper trench has not been grouted as demonstrated by the void space 20 between the rock 8 and only filled with gravel 7 .
  • the rebar 1 is only shown as a dashed line inside the concrete modified rebar 2 . This is because this modified rebar 2 does not connect to anything beyond the trench,
  • the proposed top of the fill line 35 is shown behind wall 124 .
  • the top wall has a plug 31 on the bottom that has been fitted into the slot 30 of the lower segment 124 .
  • This perspective view is looking down on a completed wall 124 and several rows of discontinuous “T” shaped trenches 121 . At this scale it is not possible to show all of the detail parts of each trench so only the modified rebars 2 are shown. The intent of the figure is to show how a retaining wall 124 can be stabilized using the modified rebar 2 and the trench 121 system as described in this patent application. There is no distinction on the ground type as this system will work with either new fill soil or existing ground.
  • FIG. 15 shows a cross section of a completed wall 124 and multiple trenches 121 staggered and discontinuous throughout the fill soil 5 .
  • These trenches 121 are completed and grout 19 is noted between the rocks 8 and the modified rebar 2 .
  • the trenches 121 directly behind the wall 124 have rebar 1 connecting to the wall in slots 22 .
  • the wall sits on a concrete foundation 15 which is founded in the existing soil 4 .
  • the top of the fill is noted as line 35 .
  • At a critical location in line 35 there is a break where tension crack 34 has opened up.
  • At the bottom of the crack 34 is the beginning of a potential failure line 27 which is bent in order to avoid the trenches 121 .
  • the typical failure line 32 is now intersecting several of the grouted trenches 121 .
  • the grouted trenches 121 have the potential to be one hundred times stronger than typical compacted fill soil 5 . They also have the advantage of being reinforced by the modified rebars 2 .
  • the basic design is to use modified rebar prefabricated to have a relatively large undulating surface of cured concrete. This undulating surface compared to the small ribs found on typical steel reinforcing bars allows the rebar to accept load from significantly weaker material such as grouted loose granular fill.
  • the modified rebar in a matrix of large rocks or demolition concrete and gravel can be grouted into a solid steel reinforced mass. When this mass is formed in a trench behind a wall it becomes a buried anchor that is tied to the surrounding soil by passive pressure depending on the shape of the trench. In addition to passive pressure it is also possible to develop friction between the trench and the soil if the grout is placed under pressure or expanding grout is used.
  • the system can be included in a high fill by staggering the trenches and using a geometric shape that is appropriate for that particular project.
  • the design process should use a computer model to determine size, shape, location, and minimum steel reinforcement.

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  • Bulkheads Adapted To Foundation Construction (AREA)

Abstract

This design is for wall and slope stabilization where the soil is stabilized by modified rebar placed in trenches excavated into the soil. The soil mass is supported by a series of grouted trenches. By excavating a series of trenches at designed locations and elevations in a soil mass where a slope and/or retaining wall is planned. The discontinuous trenches subdivide the mass into small segments thus reducing the anticipated load on the wall face or improve the stability of the soil slope. Discontinuous trenches filled with angular debris around modified steel rebar which will function as horizontal anchors for improved stability. The final step is to grout the trench fill. This will accomplish three things. First it will solidify the trench fill into a solid steel reinforced mass. Secondly, the rebars can be attached to the wall face as tie back anchors. Solid discontinuous trenches improve slope stability.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • The method of ground stabilization disclosed in this patent application uses the same steel reinforcing modification that was disclosed in U.S. Pat. No. 12,000,104 by the same inventor. For this application the use of steel reinforcing bars covered with cured concrete that has an undulating shape are referred to as modified rebar. This patent is entirely different from the previous patent and is not obvious in that discloser. The primary difference is U.S. Pat. No. 12,000,104 used modified rebars exclusively for the construction of gravity retaining walls. This application is for the construction of buried trenches in fill or natural soil for the purpose of improving the stability of the fill. This is done by installing into the soil internal stiffened linear trenches reinforced by modified rebars. Where U.S. Pat. No. 12,000,104 was for the construction of a new external gravity wall in front of existing soil.
  • This patent application also claims priority from Provisional Patent Applications 63/567,940 filed on Mar. 21, 2024, and 63/641,636 filed on May 2, 2024. These two provisional applications form the basis of this regular patent application. The first is for the construction of stable new fill with a permitter retaining wall built with precast concrete segments. The soil is stabilized by the excavation of new trenches into the new fill at an alignment perpendicular to the proposed wall face. The trenches are then filled and grouted to provide anchors for the precast wall segments. These same trenches will also provide stabilizing forces to the fill where it is in contact with the sides of the trenches, thus reducing the soil load on the wall segments.
  • The second provisional patent application uses similar steel reinforced trenches for general ground stabilization. These trenches could be used for a new or existing slope where additional stabilizing elements are desired. These trenches would be similar in construction, but they would be buried below the surface and discontinuous to prevent groundwater blockage. Also, they could be excavated in “T”, “L”, or “I” shape depending upon the soil conditions. The shapes shown on the enclosed figures are only intended to demonstrate the concept. Given the unlimited variations that trenches can take, this patent claims that any trench designed for ground stabilization and uses modified rebar as described herein is covered by this patent application. This patent is not limited to any or by any particular grouting method including the possibility of not grouting or only partially grouting the trench backfill.
    • STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
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    • THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT
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    • INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A READ-ONLY OPTICAL DISC, AS A TEXT FILE OR AN XML FILE VIA THE PATENT ELECTRONIC SYSTEM
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    • STATEMENT REGARDING PRIOR DISCLOSERS BY THE INVENTOR OR A JOINT INVENTOR
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    • TECHNICAL FIELD
  • This disclosure relates generally but not by way of limitation to the construction of in-situ ground improvement for either new compacted fill soil, existing fill soil, naturally occurring soil and rock formations and support of retaining walls by improving the stability of said formations and simultaneously acting as tie back anchors.
    • BACKGROUND OF THE INVENTION
  • A number of ground stabilization systems exist for the purpose of either building new fill, or stabilization of existing ground. The methods for building new fill involve either building retaining walls or stable slopes at the perimeter of the new fill. The method presented herein will work to stabilize either new fill or existing ground using known engineering principals and construction elements.
  • New fill is commonly stabilized by placing stabilizing elements in the fill as the layers of fill are placed and compacted. This method is known as Mechanically Stabilized Earth or MSE. These are very effective methods of stabilizing new compacted granular fill. That method relies on developing friction between the stabilizing elements and the granular fill. It also requires some form of non-erosive wall face such as concrete interlocking segments. Therefore, it is limited to sand and sandy gravelly soils. Also, MSE cannot work with an exposed slope due to the erosive nature of granular soil. The method presented in this patent application will work with a wider range of soils because it relies on active and passive pressure as well as friction. Therefore, this system will work with a wider range of soils and it is possible to construct this system with a stable nonerosive perimeter slope face.
  • Existing soils, that are fill or natural, that require additional support to ensure stability, typically are very expensive to improve. One common method of support is to construct rows of steel reinforced concrete piles commonly known as soldier piles. To provide stability they need to be set deep enough that they are founded in stable material. Constructing these large diameter piles requires large equipment and significant time for the concrete to gain sufficient strength to improve the stability of the soil mass. The method of this patent does not require large equipment, and the stabilizing force of a grouted trench will be in effect as soon as the grout is injected. This would allow for the stabilization trenches to be constructed from the edges of the unstable area and be in full effect as soon as the function prior to or without grouting if it is so designed.
    • DESCRIPTION OF RELATED ART
  • Tie back anchors for retaining walls typically use a dead man system as the earth anchor. The dead man anchor is typically a concrete block located beyond the active wedge or any calculated failure plane and attached to the wall by way of a small cable or tie rod. The cable or rod is then attached to the back of the wall.
  • New fill is commonly stabilized by placing stabilizing elements in the fill as the layers of fill are placed and compacted. This method is known as Mechanically Stabilized Earth or MSE. These are very effective methods of stabilizing new compacted granular fill. That method relies on developing friction between the stabilizing elements and the granular fill.
  • Ground improvement of existing soil and rock is typically by constructing rows of steel reinforced concrete piles commonly known as soldier piles. To provide stability they need to be set deep enough that they are founded in stable material. Constructing these large diameter piles requires large equipment and significant time for the concrete to gain sufficient strength to improve the stability of the soil mass.
    • DIFFERENCE BETWEEN SUBJECT PATENT AND RELATED ART
  • This patent provides a method for building a safe stable soil fill by constructing grouted steel reinforced discontinuous trenches within soil. The purpose of these trenches is to provide a grouted rock stiffening system to improve the overall strength of existing soil or new compacted fill without creating an impermeable groundwater barrier. In addition, the method of trench construction is easy and quick and will not impede the construction process of building a new compacted soil fill.
  • This method of ground stabilization is similar to a known landslide stabilization system that uses drilled cast in place steel reinforced concrete piles that penetrate the failure plane of the landslide. That is a method of pinning the unstable landslide mass to the stable material below the failure plane where, these piles are known as soldier piles. The soldier piles are typically constructed in rows with a designed open space between the piles.
  • The process proposed herein is similar to the soldier pile method of inserting rows of strong piles within an unstable mass to improve its stability. The process proposed would accomplish the same improvement using smaller equipment such as a backhoe and in place of soldier piles the stabilization would be provided by steel reinforced grouted trenches. The trenches would be founded horizontally beyond any failure plane as opposed to the piles extending below the failure plane.
  • For the case of a new compacted fill the unstable mass is that portion of the fill near the edge of the fill. If there is not sufficient space for a long gentle slope, then the edge needs to be constructed with steep or vertical edges. Typically, steep edges of a new soil fill require very large strong retaining walls to support the loads created by gravity acting on the fill soil at the edge of the fill. What is proposed herein is that these large forces can be counteracted by installing hardened discontinuous trenches during construction. These trenches will only occupy a small percentage of the fill volume but increase the overall strength of the fill mass, thus making the new fill stable.
  • It should be noted that compacted soil typically has a saturated unconfined shear strength on the order of 2 to 4 Pounds Per Square Inch (PSI). A trench filled with rock and or inert debris such as broken pieces of concrete, and gravel and then grouted in place would have a minimum unconfined shear strength on the order of 200 to 400 PSI. This results in a hardened zone that when properly located will cross and provide support to a potential failure plane. To prevent the hardened trench fill from fracturing or pulling apart under a tensile load the trench fill includes steel rebars. These steel rebars will be precast in concrete cover where the concrete provides minimum corrosion cover and has an undulating shape. This method of modifying the rebar prior to construction allows the rebar to be structurally tied to the rock fill. The result of placing a designed number of hardened trenches within a new compacted fill is to increase the overall strength of the fill. Then the compacted fill will have sufficient strength to resist the gravitational force pushing the fill to failure at the edge. The gravitational force results in active pressure on a hardened trench. That active pressure is transmitted through the stronger trench to stable soil which provides support in the form of passive pressure or friction. The final result is a stable over steepened or vertical slope at the edge of the new compacted fill.
  • One advantage to this system is the grouting can be delayed until a large number of trenches are ready to be grouted. The grouting process is more efficient when a large number of trenches are grouted at one time. On the other hand, if the final strength of the trench is desired during construction, then once the trench fill is complete it can be grouted immediately. Typically, chemical grout has a set time is significantly shorter than cure time for Portland cement. Therefore, if quick setting grout is used then the structural benefit of having the steel and rock filled trench in the soil would be almost immediate.
    • BRIEF DESCRIPTION OF THE PATENT
  • This patent provides a ground stabilization method that uses common building materials to construct stabilization trenches in the ground where improved stability is desired. This system will overcome some of the common limitations of existing ground improvement systems such as only working with granular soil or needing large equipment and long-time delay for the stabilization to take effect. This system would require excavating into new compacted fill or existing soil to create a series of discontinuous trenches at designed elevations and locations. The trenches would be filled with granular fill, and/or rock, modified rebar, and a grouting system as they are being constructed. The grouting system shown on the Figures uses a manifold system to improve the grout distribution. It should be noted that the same grouting could be accomplished using multiple vertical injection pipes if that would provide the desired improvement. The primary goal is to fill the naturally occurring voids when making granular deposits in the trench. If needed, each trench could be grouted as soon as the backfilling process is complete, and before the next trench is excavated. This would allow the improvement process to develop as the work is being done.
  • Once grouted the trench fill may be impermeable to ground water. This can become a problem for long or deep trenches filled with material less permeable than the surrounding soil. This is known as a groundwater barrier. Therefore, this trench design is intended to be discontinuous to ensure that the natural flow of groundwater is not impeded. Continuous trenches over long distances could be grouted provided the design includes provisions to allow for ground water to flow through the barrier or account for the change in ground water hydrology.
    • BACKGROUND INFORMATION
  • It should be noted that compacted soil typically has a saturated unconfined shear strength on the order of 2 to 4 Pounds Per Square Inch (PSI). A trench filled with rock and/or inert debris such as broken pieces of concrete, and gravel and then grouted in place would have a minimum unconfined shear strength on the order of 200 to 400 PSI. This results in a hardened zone that when properly located will cross and provide support to a potential failure plane. To prevent the hardened trench fill from fracturing or pulling apart under a tensile load the trench fill needs to include steel rebars. To prevent the corrosion of the steel rebars they will be precast in concrete, where the concrete provides minimum corrosion cover and has an undulating shape. This method of modifying the rebar prior to construction allows the rebar to be structurally tied to the rock fill. The result of placing a designed number of hardened trenches within a new compacted fill is to increase the overall strength of the fill, and thus improve the global and surficial stability. Then the compacted fill will have sufficient strength to resist the gravitational force pushing the fill to failure at the edge. The gravitational force results in active pressure on one end of the hardened trench. That active pressure is transmitted through the stronger steel reinforced trench to stable soil which provides support in the form of passive pressure or friction. The final result is a stable over steepened or vertical slope at the edge of the new compacted fill.
    • Specifications for Discontinuous Steel Reinforced Trench Stabilization System
  • A short description of the trench construction is:
      • 1. Start the mass grading operation by placing fill in thin layers and compacting it to a minimum density as determined by the engineer of record.
      • 2. Once the fill has reached the elevation for the top of the first row of trenches, then excavate trenches using a backhoe or similar equipment.
      • 3. Trenches are then filled from the top by dumping or placing cobble and or bolder size rock or inert concrete debris along with gravel up to the elevation of the modified rebar.
      • 4. The modified rebar is lowered into the partially filled trench.
      • 5. The modified rebar is then covered with more rock and gravel up to the level of the grout distribution pipe.
      • 6. The grout distribution pipe and possibly a protective wrap are then lowered into the trench.
      • 7. A final layer of cobbles and gravel are placed over the distribution pipe and around the grout injection pipe that rises above the fill.
      • 8. Above the last layer of gravel and cobbles the same fill soil is placed and compacted to seal the trench for the grouting operation.
      • 9. The last step is to inject grout into the grout injection pipe down into the grout distribution pipe where it can flow out into the void space between the gravel and rocks that surround the modified steel rebar. This process cements the rock to the concrete of the modified rebar such that the trench becomes a steel reinforced high strength cemented rock fill.
  • The above nine steps may look long or involved but if a backhoe or similar equipment is used along with a well-organized small crew, it could be completed in a relatively short period of time. It should be noted that the various parts do not need to be placed in a very precise manner for the trench to have a shear strength at least 100 times the strength of the compacted fill. As long as the modified rebars are placed near the middle of the trench and surrounded by rock or broken pieces of concrete then the transfer load from the rebar to the rock fill and visa versa will occur. This load transfer occurs directly between the rock and the concrete cover on the rebar. The purpose of the grout is not to add strength to the matrix but to lock the various parts in place such that the rocks and the modified rebar will not shift or move. In addition to locking the trench fill in place it is possible that the grout will expand into the fill helping to tie the trench to the compacted fill.
    • LIST OF FIGURES WITH SHORT DESCRIPTION
  • FIG. 1 Presents a perspective view of the initial stage of the construction of a fill that will be supported by a retaining wall that will be assembled using prefabricated wall segments installed in a series of slot cuts in the temporary false slope. Also shown are the locations of two cross sections shown as FIG. 1A and FIG. 1B.
  • FIG. 1A Shows a typical cross section of the new fill placed upon the existing soil. This section shows the fill placed against an existing soil slope.
  • FIG. 1B This figure is drawn through one of the slot cuts and the trench that will extend beyond and behind the proposed wall face.
  • FIG. 2 A perspective view of a completed retaining wall showing several segments. One of the segments is presented in a cut away view which is enlarged in FIG. 3 .
  • FIG. 3 is a perspective enlargement of the wall segment from FIG. 2 and the cut away section where the supporting trench system modified rebar is attached to the wall segment. Within the trench the modified rebar is shown with the undulating concrete cover. Under the top rebar is the grout distribution system.
  • FIG. 3 also shows the alignment of section drawings for FIG. 4A, FIG. 4B, FIG. 5A, and FIG. 5B.
  • FIG. 4A This shows a partially filled trench where a bed of rock and gravel has been placed in the bottom of the trench up to the elevation of the lower modified rebar. At the back of the trench is the vertical cut that was made into the initial compacted fill.
  • FIG. 4B The trench has now been filled to match the top of the existing grade of the initial compacted fill. This shows two modified rebar with the upper modified rebar angling down to be anchored deeper into the rock fill, and closer to the grout.
  • FIG. 5A Is a cross section of the trench partially filled with rock, modified rebar, and the grouting system. The void space between the rocks is where the grout will flow to solidify the entire mass.
  • FIG. 5B shows the cross section of a completed support trench that has been grouted. The section drawing shows two modified rebar a grout distribution system. The grout flowing between the rock through the interconnected void spaces
  • FIG. 6 shows the back of a wall segment with unmodified portion of the rebar inserted into the space within the wall opening and the opening can be filled with concrete to make the modified rebar a permanent part of the wall segment.
  • FIG. 7 shows an alternate method of modifying rebar to increase the rebar ability to transfer load to or from the surrounding material. A section of sheet metal 16 has been bent and has holes in each folded such that the rebar 1 can be inserted through the hole to join the two items together.
  • FIG. 8 presents an alternate design for modifying rebar 2 such that the rebar has a minimum concrete cover to protect the steel from corrosion. Depending upon the anticipated loading and the size of the enlarged washer shape may need additional rebar.
  • FIG. 9 presents a longitudinal section through a concrete covered modified rebar. This drawing shows the different variables that would need to be addressed for every project to have the optimum effectiveness for those projects loads and materials. It also includes two sections for different possible designs.
  • FIG. 10A shows an alternative cross section of the washer described and shown on FIG. 8 . FIG. 10A is a hexagonal shape with the primary rebar in the center and a secondary rebar within the hexagon.
  • FIG. 10B is a cross section of the washer shape presented in perspective in FIG. 8 .
  • FIG. 11 This view provides a cutaway view showing the stabilizing trenches behind a retaining wall with additional “T” shaped trenches under the sloping fill behind the wall.
  • FIG. 12 Presents a section through a partially completed wall with fill compacted up to the elevation of the lower wall segment. The wall is supported by a trench that was excavated into the partially completed fill.
  • FIG. 13 Presents the same wall and section cut view as in FIG. 12 but now the section is completed. This section shows how a second trench has been installed above and behind the first trench. The primary difference between the two trenches is modified rebar is completely within the trench for the purposes of providing tensile reinforcement to the trench fill.
  • wall with fill compacted up to the elevation of the lower wall segment. The wall is supported by a trench that was excavated into the partially completed fill. perspective view of a retaining wall with a series of “T” and “L” shaped trenches that are discontinuous and staggered throughout the fill.
  • FIG. 14 Is a perspective view of a completed wall with trenches staggered both horizontally and vertically. A reinforced multiple trench system would work to provide stabilization for new fill or existing soil.
  • FIG. 15 Shows a section view of a high wall stabilized by multiple discontinuous trenches completed and grouted. Also shown are two possible failure surfaces where the chosen surfaces encounter the trenches which have a shear strength on the order of 100 times the strength of the compacted fill. The second potential failure is shown taking a longer and difficult path to avoid the higher strength trenches.
    •  DESCRIPTION OF THE CONSTRUCTION PROCESS
  • First the trench size and locations need to be determined during the design phase of a project. This will vary from project to project and must be designed site specific. What will be the same for any project is the basic ground improvement system of installing steel reinforced trenches within a soil mass to improve the overall strength of the mass,
  • Second, the plans need to identify specific locations, elevation, shapes of the trenches, and the material to be used in the trench backfill. The findings of the design analyses and engineering requirements need to be incorporated into the plans.
  • Third, because this is not a typical compacted fill the inspection and verification of the process will need to be very through. In addition, the engineer of record will need to be kept abreast of the project continuously. Because this system uses discontinuous trenches it will be easy to modify the design during construction by adding additional trenches on short notice when necessary.
  • Fourth, along with a higher level of inspection this system will need more testing and verification systems during and shortly after construction. Typical settlement monuments should be included in the fill to track the movement of the fill as more fill soil is placed and compacted. It should be noted that movement of fill soil during the placement of additional fill is normal. What needs to be tracked is making sure the movement is within the anticipated range of movement. Another test should be made to track the air pressure inside the trench when the trench is grouted. This along with the volume of grout injected would provide confidence that the grouting operation was complete and successful.
  • The following is a list of the numbers for the Figures and what each number represents.
      • 1. Steel Rebar
      • 2. Concrete for modifying the rebar to improve their load transfer capacity.
      • 3. Concrete for all structures except rebar modification.
      • 4. Existing Soil prior to construction of the retaining wall or remaining undisturbed beyond the limits of the construction.
      • 5. Fill Soil placed and compacted in lifts.
      • 6. Sand Fill.
      • 7. Gravel fill.
      • 8. Rock or inert debris fill such as demolition concrete.
      • 9. Grout distribution pipe within a protective system.
      • 10. Geotechnical textile.
      • 11. Grout delivery pipe.
      • 12. Temporary false slope.
      • 13. Weep holes for drainage.
      • 14. Prefabricated wall segments
      • 15. Concrete footing.
      • 16. Folded metal with holes to increase the load transfer to or from steel rebar.
      • 17. Cylinder shaped concrete formed around steel rebar.
      • 18. Initial distance between slots where the false slope is a stabilizing element.
      • 19. Grout.
      • 20. Void space between rock or inert debris.
      • 21. Trench for wall or ground stabilization.
      • 22. Pocket in wall Segment for rebar tie back to anchor to the wall segment.
      • 23. Slot Cuts.
      • 24. Alignment of proposed retaining wall.
      • 25. Top of trench to be backfilled prior to resuming compaction of fill soil.
      • 26. Not used
      • 27. Potential failure surface passing under and behind steel reinforced trench.
      • 28. Not used
      • 29. Not used
      • 30. Notch in the top of wall segment to tie the upper segment to the lower segment.
      • 31. Toung in the bottom of the upper wall segment to fit into lower segment notch.
      • 32. Potential failure surface passing through some of the steel reinforced trenches.
      • 33. Not used
      • 34. Tension crack.
      • 35. Top of fill
      • 36. Vector diagram to determine the load on the retaining wall.
      • 121. Completed trench for soil and wall stabilization.
      • 124. Completed retaining wall
    FIGURES WITH DETAILED DESCRIPTION FIG. 1
  • Presents a perspective view of the initial stage of the construction of a fill that will be supported by a retaining wall. This view is prior to any of the prefabricated wall segments being installed. Fill 5 is initially constructed beyond the location of the proposed wall segments to form the temporary slope 12. The temporary fill section beyond the wall is typically sloped and is known as a false slope 12 because it will be removed as the work progresses. The figure shows two slot cuts with a distance between the slots. The distance 18 between the two slots 23 is shown as distance Z. This distance varies from one project to the next. This distance Z is determined based upon the parameters of a given project, analyses and recommendation of the Engineer of Record. In addition to the excavated slots 23 in the false slope each slot is shown with a narrow trench 21 behind the proposed location of the wall. These slots are for the construction of stabilization trenches that will include modified rebars that will be attached to each of the wall segments. FIG. 1 shows the location of two typical section views labeled FIG. 1A and FIG. 1B.
    • FIG. 1A
  • This figure shows a typical cross section of the new fill 5 placed upon the existing soil 4. This section shows the fill placed against an existing soil slope 4. This is only an example and not a limit to the use of this design. With two or more walls this same design could be used to rase the grade a significant distance one row of wall segments at a time. Fill 5 has a slope that extends beyond the alignment 24 of the proposed retaining wall to ensure temporary stability.
    • FIG. 1B
  • This figure is drawn through one of the slot cuts 23 the trench 21 that will extend beyond and behind the proposed wall face alignment 24. Because the slot has been cut into fill 5 the slot has removed the false slope 12 which is now shown as a dashed line. The existing ground 4 below and beyond the fill is shown.
    • FIG. 2
  • Presents a perspective view of a completed retaining wall showing several wall segments 14 with each connected and to a completed trench 121. Each trench 121 has a grout injection tube 11 that extends down into the trench 121 fill. One of the segments is presented in a cut away view which is enlarged in FIG. 3 . The cut away exposes the internal section of the wall segment 14 and the support system located inside the trench 121 along with the grout system. Also shown are the weep holes 13 in the base of the wall segments 14. These are located just above the concrete channel footing 15. Just in front of footing 15 and behind the fill is the existing or native soil 4.
    • FIG. 3
  • FIG. 3 is a perspective enlargement of the wall segment 14 from FIG. 2 and the cut away section where the supporting trench 121 system intersects the wall segment 14. The wall segments 14 are shown with the weep holes 13 and the concrete footing 15. Within the cut away the original compacted fill 5 is exposed behind the wall and next to the trench 121. Within the trench the modified rebar 2 is shown with the undulating concrete cover 2 inside the trench. The same rebar 1 is shown without concrete cover 2 as it enters the formed pocket 22 in the back of the wall segment 14. The pocket will be filled with concrete grout which will also cover the exposed portion of rebar 1. It should be noted that the rebar 1 with its modified concrete covered section 2 is the top rebar. Under the top rebar is the grout distribution pipe 9 which is surrounded by coarse sand 6 all within the protective geotextile wrap 10. This prevents pipe 9 from being damaged by the rock or inert concrete debris 8 that is placed on top and on the sides of the grout pipe 9. Along with rock fill 8 the larger voids are filled with gravel 7. The grout delivery pipe 11 vertically rises out of the filter cloth 10 to an elevation above the trench 121 where it can be attached to a grout generating system which is not shown.
  • FIG. 3 shows the alignment of section drawings for FIG. 4A, FIG. 4B, FIG. 5A, and FIG. 5B. The FIGS. 4A and 4B are longitudinal sections of the trenches. FIG. 4A being made when the trench 21 is only partially filled and FIG. 4B shows the trench 121 filled but not grouted. FIG. 5A shows a cross section of the trench 21 partially filled and FIG. 5B presents a cross section of the trench 121 completed and grouted.
    • FIG. 4A
  • This shows a partially filled trench where a bed of rock 8 and gravel 7 has been placed in the bottom of the trench 21 up to the elevation of the lower modified rebar 2. A zone of sand 6 has been compacted in the front of the trench 21 between the rock 8 and where the back side of the wall segment 14 will be placed on top of concrete footing. Above the footing 15 is the rebar 1 which is the same rebar shown as a dashed rebar within the concrete cover 2. The modified concrete covered rebar 2 has been placed on top of rock 8 and gravel 7 fill that has been placed at that time. At the back of the trench 21 is the vertical cut that was made into the initial compacted fill 5.
    • FIG. 4B
  • The trench 21 has now been filled to become trench 121 as it now matches the top of the existing grade of the initial compacted fill 5. This design shows two modified rebar 2, however what is claimed is that each project will require an individual design which may require more or fewer modified rebar, or wall segments 14 supported by more than one supporting trench 121. The upper modified rebar 2 is shown angling down to be anchored deeper into the rock 8 fill, and closer to the grout distribution pipe 9. Between the two modified rebars 2 is the grout distribution pipe 9 surrounded by the sand 6 and the geotechnical cloth 10 wrapped around to protect the pipe 9 from damage during construction. The grout injection pipe 11 rises out of the trench fill starting from a “T” connection with the distribution pipe 9. The rock 8 fill is capped with the same compacted fill soil 5 used for the initial compacted soil 5 fill. At the front of the rock 8 fill is a zone of sand 6 behind the wall segment 14. The wall segment 14 which is supported by the concrete footing 15 and held in place by the two rebars 1 inserted into the back of the wall segment 14. With the weight of the rock 8 on and around the two modified rebar 2 it is possible that the wall segment 14 is temporarily stable and although it is ready for grout 19 to be injected into the trench the injection of the grout 19 could wait until all, or a large number of segments 14 are ready for grouting. This flexibility in timing of injecting grout 19 could improve the economy of the overall project.
    • FIG. 5A
  • FIG. 5A is a cross section of the trench 21 partially filled with rock 8, modified rebar 2 and the grouting system. The grouting system consists of the central grout distribution pipe 9 surrounded by sand 6 wrapped in geotechnical filter cloth 10. Also shown is the grout injection pipe 11 connected to grout distribution pipe 9. The void space 20 between the rock 8 is where the grout will flow into the fill to solidify the entire mass once the trench fill is complete.
    • FIG. 5B
  • FIG. 5B shows a cross section of a completed support trench 121 that has been grouted. The section drawing shows two modified rebar 2 and one grout distribution system where the grout 19 has flowed out between the grains of sand 6 and through the geotechnical filter cloth 10 and out into the void space 20. Depending on the grout 19 and the compacted fill soil 5 the grout 19 may flow beyond the trench wall into the compacted fill soil 5. This would tie the trench rock 8 fill to the compacted soil fill 5 beyond the limit of the initial trench 21 excavation. At the top of the trench is a layer of the fill soil 5 that has been recompacted over the rock 8 fill prior to grouting to help keep the grout 19 flowing between the rock 8 through the interconnected void space 20. With grout 19 surrounding the rocks 8, the rocks 8 are now locked in place such that modified rebars 2 are also locked in place. This results in the wall segment 14 becoming stable because it is attached to the modified rebar 2.
    • FIG. 6
  • FIG. 6 shows the back side of a possible design for wall segments 14. The drawing shows a wall segment 14 with a rectangular indentation 22 with horizontal rebar 1 that cross the opening such that the unmodified rebar 1 section can be inserted into the space between the concrete of the segment 14 and the horizontal rebar 1. Once the rebar 1 section of the modified rebar 2 is in place then a cover can be placed over the opening and the opening can be filled with concrete to make the modified rebar 2 a permanent part of the wall segment 14.
    • FIG. 7
  • FIG. 7 shows an alternate method of modifying rebar 1 to increase the rebar 1 ability to transfer load to or from the surrounding material. A section of sheet metal 16 has been bent and has holes in each folded such that the rebar 1 can be inserted through the hole to join the two items together. For this design there is no concrete corrosion protection. For some conditions this may be acceptable. Another method would be to place grout 19 or cement 3 around the rebar 2 after the two parts are assembled. It is possible to use this design for the trench stabilization system described herein.
    • FIG. 8
  • FIG. 8 presents another alternate design for creating modifying rebar 2 such that the rebar 1 has a minimum concrete 2 cover to protect the steel from corrosion. Then spaced at designed intervals are washer shaped enlarged sections. The purpose of the enlarged sections is to improve the load transfer from surrounding material to the rebar 1 that runs through the center portion of the concrete to form a modified rebar 2 system. Depending upon the anticipated loading and the size of the enlarged washer shaped section the enlarged section may need additional rebar 1 formed into a circular shape to reinforce that portion of the modification of the center rebar 1 as shown for one of the washers presented on this figure. It is possible to use this design for the trench stabilization system described herein.
    • FIG. 9
  • FIG. 9 presents a longitudinal section through a concrete covered modified rebar 2. The purpose of this drawing is to show the different variables that would need to be addressed for every project to have the optimum shape. These variables would apply regardless of the cross-sectional shape. As shown variable “D” is the minimum distance to provide safe cover for the rebar 1 to ensure that the rebars 1 have proper corrosion protection. Variable “A” is the angle of the slope between the minimum cover cylinder 17 alignment and the slope up to the outer portion of the undulating concrete cover. Variable “A” could range from 10 to 90 degrees. Variable “F” is the angle of the slope between the minimum cover cylinder 17 alignment and the slope down from the outer portion of the undulating concrete cover. Variable “F” could range from 10 to 90 degrees. Distance “C” is the space between the base points along the minimum cover cylinder 17 between two ridges. Variable “B” is the width of the extreme limit of the ridge. Variable “E” is the height of the ridge beyond the minimum cover cylinder 17. The FIG. 10A is cross-section through a typical ridge. FIG. 10B is also a cross-section through another design of a ridge.
    • FIG. 10A
  • This view shows an alternative cross section of the washer shaped enlarged section described and shown on FIG. 8 . For FIG. 10A a hexagonal shape is presented, however this is only to demonstrate that a geometric shape could be used in place of a round shaped washer. This view shows the primary rebar 1 in the center and a secondary rebar 1 in a circular shape to reinforce the hexagon.
    • FIG. 10B
  • FIG. 10B is a cross section of the washer shape presented in perspective in FIG. 8 . This view shows the primary rebar 1 in the center and a secondary rebar 1 in a circular shape to reinforce the circle.
    • FIG. 11
  • This view provides a cutaway view showing the stabilizing trench 121 behind a retaining wall 124 and under the sloping compacted fill 5 behind the wall. The trench directly behind the wall has modified rebars 2 that are attached to the wall at slot 22. Inside slot 22 is the rebar 1. This trench acts as a tie back for stabilizing the wall 124. Above and behind the wall are two “T” shaped stabilizing trenches 121 that have sufficient space between them to allow for drainage. It should be noted that the trenches 121 in this view only show the outline of the trench and the modified rebar 2. The completed trenches would include the rock and gravel fill that has been grouted in place and surrounding the modified steel rebar 2. The scale of this Figure does not allow for these details to be shown but they would be the same as presented on FIG. 5B. The grouted fill will obscure view of the modified steel rebar 2. The “T” shape is intended to provide stabilization for the fill located behind the trench that runs up the slope. The modified rebars 2 tie the trench fill together and tie the front trench 121 to the back section of the trench 121 for stability.
    • FIG. 12
  • Presents a section through a partially completed wall 124 with soil 5 fill compacted up to the elevation of the lower wall 124 segment. The lower section of wall 124 is supported horizontally by a trench that was excavated into the partially completed fill soil 5. The section is drawn through the middle of the trench exposing the modified rebar 2 and the grout system. The grouting system consists of the grout injection pipe 11 going into the geotechnical filter cloth 10 to the grout distribution pipe 9 surrounded by sand 6 wrapped in geotechnical filter cloth 10. Along with the stabilizing system the section cuts through the subdrain system including the sand 6 pocket and the drainpipe 13. Also shown is the pocket 22 in the back of the wall along with rebar 1. The wall segment 124 is supported by footing 15 founded in the existing soil 4. The top of wall segment 124 has a slot 30 for the next segment to fit into.
    • FIG. 13
  • This shows the same view as FIG. 12 except the next wall 124 segment has been added along with new compacted soil 5 fill and an additional trench of the same design and construction. The trenches are staggered both horizontally and vertically to ensure that drainage is not blocked. Both trenches have the same grouting system. The grouting system consists of the grout injection pipe 11 going into the geotechnical filter cloth 10 to the grout distribution pipe 9 surrounded by sand 6 wrapped in geotechnical filter cloth 10. The lower trench is shown to be grouted with grout 19 filling the void space around the rock 8 and the modified rebar 2. The upper trench has not been grouted as demonstrated by the void space 20 between the rock 8 and only filled with gravel 7. The rebar 1 is only shown as a dashed line inside the concrete modified rebar 2. This is because this modified rebar 2 does not connect to anything beyond the trench, The proposed top of the fill line 35 is shown behind wall 124. The top wall has a plug 31 on the bottom that has been fitted into the slot 30 of the lower segment 124.
    • FIG. 14
  • This perspective view is looking down on a completed wall 124 and several rows of discontinuous “T” shaped trenches 121. At this scale it is not possible to show all of the detail parts of each trench so only the modified rebars 2 are shown. The intent of the figure is to show how a retaining wall 124 can be stabilized using the modified rebar 2 and the trench 121 system as described in this patent application. There is no distinction on the ground type as this system will work with either new fill soil or existing ground.
    • FIG. 15
  • FIG. 15 shows a cross section of a completed wall 124 and multiple trenches 121 staggered and discontinuous throughout the fill soil 5. These trenches 121 are completed and grout 19 is noted between the rocks 8 and the modified rebar 2. The trenches 121 directly behind the wall 124 have rebar 1 connecting to the wall in slots 22. The wall sits on a concrete foundation 15 which is founded in the existing soil 4. The top of the fill is noted as line 35. At a critical location in line 35 there is a break where tension crack 34 has opened up. At the bottom of the crack 34 is the beginning of a potential failure line 27 which is bent in order to avoid the trenches 121. This results in a lower load being placed on wall 124 than what would be potential failure line 32 which is strait. What is being demonstrated is that the typical failure line 32 is now intersecting several of the grouted trenches 121. When constructed properly the grouted trenches 121 have the potential to be one hundred times stronger than typical compacted fill soil 5. They also have the advantage of being reinforced by the modified rebars 2.
    • SUMMARY OF INVENTION
  • The basic design is to use modified rebar prefabricated to have a relatively large undulating surface of cured concrete. This undulating surface compared to the small ribs found on typical steel reinforcing bars allows the rebar to accept load from significantly weaker material such as grouted loose granular fill. Following the method outlined herein the modified rebar in a matrix of large rocks or demolition concrete and gravel can be grouted into a solid steel reinforced mass. When this mass is formed in a trench behind a wall it becomes a buried anchor that is tied to the surrounding soil by passive pressure depending on the shape of the trench. In addition to passive pressure it is also possible to develop friction between the trench and the soil if the grout is placed under pressure or expanding grout is used. Where trenches are constructed parallel to each other the result is that the soil behind the wall is stabilized and subdivided into individual sections that are supported on each side by the grouted trench fill which reduces the active pressure on the wall. Thus, these sections of the fill are now large individual stable masses that will stabilize the remainder of the fill. This is similar to a MSE gravity wall with the advantage of working with a wider range of soil types, including existing soil.
  • As shown the system can be included in a high fill by staggering the trenches and using a geometric shape that is appropriate for that particular project. As noted above the design process should use a computer model to determine size, shape, location, and minimum steel reinforcement.

Claims (9)

1. I claim that the system of casting concrete on steel rebar and allowing it time to cure will allow for the steel reinforcement of fill material placed within a trench excavation for ground stabilization improvement and exposed portions of said rebar can be incorporated into external structures such as retaining walls, structural foundations, or ground anchor system, along with the concrete covered steel rebar the trenches can be filled with a variety of solid inert material such as pieces of concrete that comes from other sources such as demolition of existing structures, waste concrete that is broken to sizes less than 30 centimeters, rock that is cobble size or small boulders, gravel and coarse sand, such that the trench fill will be sufficiently porous for injected grout to fully penetrate ultimately to form a solid steel reinforced mass within the initial trench excavation to improve the overall stability of the ground.
2. I claim that the above referenced claim 1 steel reinforced trench can take any shape that will be compatible with the limitations or needs of any given site.
3. I claim that the above referenced claim 1 steel reinforced trench can be used for the stabilization of new compacted fill soil and the trenches can be constructed at locations and intervals to function as tieback anchors for a wall face.
4. I claim that the above referenced claim 1 steel reinforced trench can be used for the stabilization of existing fill soil or naturally occurring soil deposit and could be used for stabilization of new or existing retaining walls by acting as a tie back or providing additional stability where needed.
5. I claim that the above referenced claim 1 steel reinforced trench can be used for both long term and temporary improvement of the stability of any soil or rock formation.
6. Steel reinforced grouted trenches can be constructed in any shape desired to satisfy the needs for a given project.
7. Steel reinforced trenches can be grouted using a manifold system to distribute the grout or a series of tubes for the length of the trench.
8. I claim priority for the shapes and design of the concrete cover over the steel rebars presented in this patent application.
9. The shape of the concrete cover over the steel rebars can vary from one project to another or even within a given project.
US19/086,070 2024-03-21 2025-03-20 Steel Reinforced Trench Fill for Ground Stabilization Pending US20250320683A1 (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3324207A (en) * 1965-06-16 1967-06-06 James M Shilstone Method of placing concrete with a predetermined selected placement of aggregate
US3975917A (en) * 1974-08-22 1976-08-24 Kingo Asayama Flanged foundation pile group and method of constructing a foundation by means of the same
US5472296A (en) * 1992-08-20 1995-12-05 Dyckerhoff & Widmann Aktiengesellschaft Corrosion protected support element for a soil anchor or a rock anchor, a pressure pile or the like
US20010023568A1 (en) * 2000-01-13 2001-09-27 Edwards Christopher M. Reinforcing bars for concrete structures
US10501905B2 (en) * 2016-08-10 2019-12-10 Korea Institute Of Civil Engineering And Building Technology Wave-shaped grouting bulb of micropile and method for forming same
US20220356663A1 (en) * 2020-10-19 2022-11-10 Theo Robert Seeley Load Transfer System
US11959238B1 (en) * 2023-06-05 2024-04-16 Nanjing Institute Of Environmental Sciences, Mee Treatment system and method for sandy soil landfill solid waste polluted river channel

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3324207A (en) * 1965-06-16 1967-06-06 James M Shilstone Method of placing concrete with a predetermined selected placement of aggregate
US3975917A (en) * 1974-08-22 1976-08-24 Kingo Asayama Flanged foundation pile group and method of constructing a foundation by means of the same
US5472296A (en) * 1992-08-20 1995-12-05 Dyckerhoff & Widmann Aktiengesellschaft Corrosion protected support element for a soil anchor or a rock anchor, a pressure pile or the like
US20010023568A1 (en) * 2000-01-13 2001-09-27 Edwards Christopher M. Reinforcing bars for concrete structures
US10501905B2 (en) * 2016-08-10 2019-12-10 Korea Institute Of Civil Engineering And Building Technology Wave-shaped grouting bulb of micropile and method for forming same
US20220356663A1 (en) * 2020-10-19 2022-11-10 Theo Robert Seeley Load Transfer System
US11959238B1 (en) * 2023-06-05 2024-04-16 Nanjing Institute Of Environmental Sciences, Mee Treatment system and method for sandy soil landfill solid waste polluted river channel

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