JP2016037715A - Ground improvement pile and ground improvement method - Google Patents

Abstract

[PROBLEMS] To promote consolidation of fine-grained ground while reducing construction costs and shortening the construction period, and to eliminate excess pore water pressure in coarse-grained ground and compact coarse-grained ground The ground improvement pile and the ground improvement construction method which can carry out are provided. The present invention relates to a ground improvement pile 1 provided in a ground 8. The ground improvement pile 1 to which the present invention is applied is surrounded by a pile side surface portion 2 and a pile side surface portion 2 which are inclined in the axial direction Y from one end portion 1a to the other end portion 1b and formed in a substantially tapered shape. And a pile inside 3 formed in a substantially hollow shape. The pile side surface portion 2 is formed with one or a plurality of through holes 5 so as to penetrate to the pile interior 3. [Selection] Figure 2

Description

  The present invention relates to a ground improvement pile provided in the ground and a ground improvement method for providing a ground improvement pile in the ground.

  Conventionally, the vertical drain method for the purpose of promoting the consolidation of the viscous ground, and the patent documents 1 and 2 for the purpose of dissipating excess pore water pressure of the sandy ground and compacting the sandy ground The disclosed ground improvement method has been proposed.

  The vertical drain construction method is a construction method in which a large number of sand piles or the like are driven vertically into a clay layer, and the embankment load is placed above the sand pile, whereby the clay layer is quickly consolidated and dewatered to increase the ground strength.

  In the gravel drain disclosed in Patent Document 1, a material having a particle size in a range that can be used as a drain material among materials selected by the particle size is created and arranged on the ground as a gravel drain pile at a predetermined interval. The material having a particle size in the range other than the above is formed and arranged as a compacted pile at the center of the gravel drain pile or around the gravel drain pile.

  The liquefaction suppression pile disclosed in Patent Document 2 has a large number of holes, and a drainage member provided with a water-permeable filter in the holes along the longitudinal direction of the pile. In the applied liquefaction suppression pile, the hole provided with the filter is pre-filled with a substance that dissolves in water after a predetermined time.

  The structure for countermeasures against liquefaction of the foundation ground of a building disclosed in Patent Document 3 includes a plurality of taper piles having a tapered portion whose outer diameter is reduced from one end side toward the other end side. To form a group pile on the surface layer part of the foundation ground of the building including the formation layer by pressing or rotating the other end part with a small outer diameter downward into the ground using a heavy press machine It is configured by installing in a grid pattern at a predetermined pitch and compacting the surface layer portion of the foundation ground.

JP 2001-11848 A Japanese Patent Laid-Open No. 03-286016 JP 2008-190116 A

  However, because the vertical drain method is to load the embankment load above the sand pile, etc., the clay layer is consolidated quickly, so the construction cost for creating the embankment is increased and the construction period is prolonged. There was a problem of concern.

  In addition, the gravel drain disclosed in Patent Document 1 is to separately create and place a gravel drain pile and a compacted pile, so that the construction cost for separately creating and placing each pile is increased. There was a problem that the construction period was prolonged.

  Moreover, the liquefaction suppression pile disclosed by patent document 2 attaches the drainage member which has many hole parts along the longitudinal direction of a pile, and provides the drainage function, The excess pore water pressure of sandy ground However, it is not intended to promote consolidation of viscous land.

  Furthermore, the liquefaction countermeasure structure of the foundation ground of the building disclosed in Patent Document 3 increases the peripheral frictional force of the tapered pile by bringing the outer peripheral surface of the tapered pile and the surrounding foundation ground into close contact with each other. However, there is a problem that the excess pore water pressure of the sandy ground cannot be dissipated and the prevention of liquefaction of the sandy ground is insufficient. It was.

  Therefore, the present invention has been devised in view of the above-mentioned problems, and its object is to promote consolidation of fine-grained ground while reducing the construction cost and shortening the construction period. It is another object of the present invention to provide a ground improvement pile and a ground improvement construction method that can carry out dissipation of excess pore water pressure of coarse ground and compaction of coarse ground.

  The ground improvement pile according to the first invention is a ground improvement pile provided in the ground, and is a pile side face portion formed in a substantially tapered shape by being inclined from one end portion to the other end portion in the axial direction. And a pile interior surrounded by the pile side face portion and formed in a substantially hollow shape, wherein the pile side face portion is formed with one or a plurality of through holes so as to penetrate to the inside of the pile. To do.

  The ground improvement pile according to the second invention is characterized in that, in the first invention, the pile is provided with a heavy material using a stone or steel slag.

  The ground improvement pile according to the third invention is characterized in that, in the first invention or the second invention, the pile side surface portion is made of an iron material, an aluminum material or a vinyl chloride material.

  The ground improvement construction method according to the fourth invention is a ground improvement construction method in which a ground improvement pile is provided in the ground, and is a pile formed in a substantially tapered shape by being inclined from one end to the other end in the axial direction. One or a plurality of through-holes are formed so as to penetrate through the side of the pile to the inside of the pile. A ground improvement pile is provided in the ground, and the groundwater flowing through the through hole and flowing into the pile is drained to the ground during normal times or during an earthquake.

  According to 1st invention-4th invention, since a pile side part is formed in a substantially taper shape, and a through-hole is formed in a pile side part and the inside of a pile is formed in a substantially hollow shape, When it is installed in fine-grained ground, it is possible to promote consolidation of fine-grained ground and promote dehydration of fine-grained ground without the need for preload structures such as embankments. When ground improvement piles are installed in coarse-grained ground, the excess pore water pressure in the coarse-grained ground due to groundwater drainage is dissipated, and the coarse-grained ground is compacted by increasing the residual earth pressure around the pile. Can be carried out.

It is a perspective view which shows the ground improvement pile which applied this invention. It is a front view which shows the state in which the ground improvement pile which applied this invention was provided in the ground. (A) is a front view which shows the ground improvement pile which applied this invention, (b) is the BB sectional view, (c) is the CC sectional view. It is a front view which shows the state by which the heavy material was provided in the pile inside of the ground improvement pile which applied this invention. (A) is a front view which shows the state in which the ground improvement pile which applied this invention was provided in the fine-grained ground, (b) is the ground improvement pile which applied this invention in the coarse-grained ground It is a front view which shows the state provided in. (A) is a front view which shows the residual earth pressure in the ground by the conventional ground improvement pile, (b) is a front view which shows the residual earth pressure in the ground by the ground improvement pile which applied this invention. . It is a graph which shows the comparison with the residual earth pressure of the conventional ground improvement pile, and the residual earth pressure of the ground improvement pile which applied this invention. It is a front view which shows the state where the ground improvement pile which applied this invention is provided in a fine-grained ground, and groundwater is drained. (A) is a front view which shows the state by which the embankment was provided in the conventional ground improvement pile, (b) is the state by which the ground improvement pile which applied this invention was provided in the ground, without creating embankment FIG. It is a front view which shows the state by which the ground improvement pile which applied this invention is provided in a coarse-grained ground, and groundwater is drained. It is an enlarged front view which shows the state through which a groundwater passes a through-hole with the ground improvement pile which applied this invention. It is a front view which shows the state which prevented the lifting of the pile with the dead weight of the heavy material with the ground improvement pile which applied this invention. It is a front view which shows the state in which the soil particle in a ground is filtered with a weight material with the ground improvement pile which applied this invention, and only groundwater is drained to the ground.

  Hereinafter, the form for implementing the ground improvement pile 1 to which this invention is applied is demonstrated in detail, referring drawings.

  As shown in FIG. 1, a ground improvement pile 1 to which the present invention is applied is provided by placing a pile such as a steel pipe pile into the ground 8 in order to improve the ground of viscous soil or sandy soil. The pile side part 2 formed by outer peripheral surfaces, such as a steel pipe pile, and the pile inside 3 formed inside the steel pipe pile etc. are provided.

  As shown in FIG. 2, the ground improvement pile 1 to which the present invention is applied is provided by driving the tip end portion 1 a of the pile to the deep layer side 8 a of the ground 8, and the base end portion of the pile on the surface layer side 8 b of the ground 8. 1b is provided. The ground improvement pile 1 to which the present invention is applied may be such that the leading end 1a of the pile reaches the supporting ground on the deep side 8a of the ground 8, and the leading end 1a of the pile does not reach the supporting ground. Also good.

  The ground improved pile 1 to which the present invention is applied has a small pipe diameter in the axial orthogonal direction X at the tip end 1a of the pile and a large pipe diameter in the axial orthogonal direction X at the base end part 1b of the pile. As a diameter, it is formed so that the pipe diameter in the axial orthogonal direction X gradually increases in the axial direction Y from the leading end 1a of the pile to the proximal end 1b of the pile.

  In the ground improvement pile 1 to which the present invention is applied, a blocking member 4 such as a steel plate is attached to the lower end of the pile side face portion 2 by welding or the like so as to close the tip end portion 1a of the pile. The ground improvement pile 1 to which the present invention is applied is provided in the ground 8 as a tip closed pile by being driven into the ground 8 in a state where the tip end portion 1 a of the pile is closed with the closing member 4.

  As the ground improvement pile 1 to which the present invention is applied, for example, a steel pipe pile, an aluminum pipe or a vinyl chloride pipe is used. When the steel pipe pile is used, the pile side surface portion 2 uses an iron material whose main material is steel, stainless steel, or the like. Moreover, when the aluminum pipe is used, the pile side part 2 is made of an aluminum material whose main material is aluminum, and when the polyvinyl chloride pipe is used, the main material is polyvinyl chloride or the like. A vinyl chloride material is used.

  As shown in FIG. 3, the pile side surface portion 2 is formed so that the pipe diameter of the pile in the axial center orthogonal direction X gradually increases in the axial direction Y from the distal end portion 1 a of the pile to the proximal end portion 1 b of the pile. Thus, the taper is substantially tapered by being inclined at a predetermined gradient θ so as to expand in the axial direction Y from one end serving as the tip end 1a of the pile to the other end serving as the base end 1b of the pile. It is formed in a shape.

  As shown in FIG. 3A, the pile side surface 2 is formed in a substantially tapered shape with a gradient θ of about 1/25 to 1/200. For example, the pile side surface 2 has a pile pipe diameter R1 of the pile tip end 1a of 18 cm, a pile pipe diameter R2 of the pile base end 1b of 50 cm, and the pile extension L in the axial direction Y is 630 cm. Then, it is formed in a substantially tapered shape with a gradient θ of about 1/40.

  The pile side surface portion 2 is formed with one or a plurality of through holes 5 so as to penetrate to the inside 3 of the pile by drilling the outer peripheral surface of a steel pipe pile or the like. The pile side surface portion 2 has a predetermined opening ratio with respect to the entire surface area of the pile side surface portion 2 by being opened by a plurality of through holes 5 penetrating to the inside 3 of the pile. For example, the pile side surface portion 2 It has an aperture ratio of about 3% to 20% of the entire surface area.

  The through hole 5 is formed in a substantially circular shape having a diameter of 2 mm to 5 mm or less, for example. The through-hole 5 may be formed in the pile side surface portion 2 in an amount substantially proportional to the pipe diameter of the pile gradually increasing from the tip end portion 1a of the pile in the axial direction Y to the base end portion 1b of the pile. The pile side surface portion 2 may be formed in a substantially equal quantity at each site in the axial direction Y. The through hole 5 is not limited to this, and may be formed in the pile side surface portion 2 in any shape, size, and quantity.

  The pile interior 3 is formed in a substantially hollow shape by being surrounded by a pile side face portion 2 serving as an outer peripheral surface of the steel pipe pile or the like by forming the steel pipe pile or the like into a substantially cylindrical truncated cone shape. In the pile interior 3, the pile side surface portion 2 is formed in a substantially tapered shape from the tip end portion 1a of the pile to the base end portion 1b of the pile in the axial direction Y. ), The internal cross-sectional area A2 is relatively large at the base end portion 1b of the pile, and the internal cross-sectional area A1 is relatively small at the tip end portion 1a of the pile, as shown in FIG. Become.

  As shown in FIG. 4, the pile interior 3 is provided with a weight material 6 using stone materials such as gravel and crushed stone, or steel slag such as blast furnace slag and steelmaking slag as necessary. As the weight material 6, for example, a material whose grain size is adjusted so as not to pass through the through hole 5 is used. As for the weight material 6, assuming that the specific gravity dw based on the mass of water (4 ° C.) is larger than the specific gravity ds of the sand of the ground 8, the specific gravity ds of sand is about 1.7 to 1.9, for example. In the case of stone, the specific gravity dw is about 2.1 to 2.6, and in the case of steel slag, the specific gravity dw is about 2.6 to 3.6.

  As shown in FIG. 5 (a), the ground improvement pile 1 to which the present invention is applied is shown in FIG. 5 (b). As shown, it is provided on the coarse-grained ground 82 having a coarse-grained portion of sandy soil, gravelly soil, etc. exceeding 50%. Here, the fine particles such as cohesive soil and silt are those having a particle size of 0.074 mm or less, and the coarse particles such as sandy soil and gravelly soil are the particle size of the soil particles. Is over 0.074 mm.

  As shown in FIGS. 6 and 7, the ground improvement pile 1 to which the present invention is applied is driven into the ground 8 so that the piles of steel pipe piles and the like separate the soil particles of the existing ground 8. Therefore, the residual earth pressure P of the surrounding ground of the pile increases from the pile side surface portion 2 into the ground 8 in the direction orthogonal to the axis X.

  As shown in FIG. 6 (a), the conventional ground improvement pile 9 has an axial center direction Y from one end portion that becomes the tip end portion 9a of the pile to the other end portion that becomes the base end portion 9b of the pile. It is formed in a straight shape with substantially the same tube diameter. In the conventional ground improvement pile 9, the pipe diameter R1 of the pile at the tip end portion 9a of the pile and the pipe diameter R2 of the pile at the base end portion 9b of the pile are 34 mm, and the extension L of the pile in the axial direction Y is 630 mm. When this is done, the residual earth pressure P (kPa) of the ground around the pile at each depth in the axial direction Y is represented, as indicated by the crosses in FIG.

  On the other hand, the ground improvement pile 1 to which the present invention is applied, as shown in FIG. 6 (b), from one end that becomes the leading end 1a of the pile to the other end that becomes the base end 1b of the pile. The pile side surface portion 2 is formed in a substantially tapered shape so as to increase in diameter in the axial direction Y up to the portion. In the ground improvement pile 1 to which the present invention is applied, the pipe diameter R1 of the pile at the tip end 1a of the pile is 18 mm, and the pipe diameter R2 of the pile at the base end 1b of the pile is 50 mm. When the extension L is 630 mm, the residual earth pressure P (kPa) of the ground around the pile at each depth in the axial direction Y is represented as indicated by the □ marks in FIG.

  At this time, the ground improvement pile 1 to which the present invention is applied is a conventional ground improvement pile formed in a straight shape by the pile side surface portion 2 being formed in a substantially tapered shape so as to expand in the axial direction Y. Compared with 9, the residual earth pressure P of the surrounding ground of the pile is increased by the total length from the leading end 1a of the pile to the proximal end 1b of the pile. The ground improvement pile 1 to which the present invention is applied is particularly compared to the conventional ground improvement pile 9 in which the base end 1b side of the pile is formed in a straight shape rather than the tip end 1a side of the pile. The increase rate of the residual earth pressure P in the surrounding ground becomes large.

  As shown in FIG. 5 (a), the ground improvement pile 1 to which the present invention is applied is provided in a fine-grained ground 81 in which fine particles such as cohesive soil and silt account for 50% or more. As shown, the existing ground water W in the ground 8 is drained to the ground 80 at normal times. The ground improvement pile 1 to which the present invention is applied drives the existing groundwater W in the ground 8 until the existing fine grain ground 81 is sufficiently consolidated and dewatered by driving a steel pipe pile or the like into the ground 8. By draining to the ground 80 at a normal time, the fine-grained ground 81 is changed from the soft ground to the hard ground, and the existing fine-grained ground 81 is improved.

  In the ground improvement pile 1 to which the present invention is applied, the pile side surface portion 2 is formed in a substantially tapered shape so as to expand in the axial direction Y from the distal end portion 1a of the pile in the axial direction Y to the proximal end portion 1b of the pile. Then, by increasing the residual earth pressure P on the ground around the pile, a large pressing force acts on the soil particles of the fine-grained ground 81, and the compaction and dehydration of the fine-grained ground 81 are remarkably promoted.

  At this time, the ground improvement pile 1 to which the present invention is applied has a through-hole 5 penetrating to the inside 3 of the pile formed in the pile side surface portion 2 and the pile side surface portion 2 is opened at a predetermined opening ratio. The existing groundwater W dehydrated by the consolidation of the grain land board 81 passes through the through hole 5 and flows into the pile interior 3. In the ground improvement pile 1 to which the present invention is applied, the water level of the groundwater W flowing into the pile interior 3 gradually rises in the pile interior 3, and the groundwater W is drained from the pile interior 3 to the ground 80 at the base end 1 b of the pile. Will be.

  In the conventional vertical drain method, as shown in FIG. 9 (a), a preload structure such as embankment 90 is formed on the ground 80 above the conventional ground improvement pile 9 formed in a straight shape, and embankment 90, etc. The residual earth pressure P of the surrounding ground of the pile is increased by applying a load of its own weight to the ground 8. On the other hand, the ground improvement pile 1 to which the present invention is applied, as shown in FIG. 9 (b), the pile side surface portion 2 is formed in a substantially tapered shape so that the residual earth pressure P on the surrounding ground of the pile is reduced. Since it can be increased, it is not necessary to create the embankment 90 or the like unlike the conventional vertical drain method.

  Thereby, the ground improvement pile 1 which applied this invention increases the residual earth pressure P of a surrounding ground, without forming preload structures, such as embankment 90, by forming the pile side part 2 in a substantially taper shape. Therefore, the construction cost for ground improvement can be reduced and the construction period for ground improvement can be shortened on the assumption that no preload structure such as embankment 90 is required.

  In the case where the ground improvement pile 1 to which the present invention is applied is provided in a fine-grained ground 81 having a fine-grained portion such as cohesive soil or silt that occupies 50% or more, as shown in FIG. Under normal circumstances, the existing groundwater W in the ground 8 is drained to the ground 80, and the pile side surface portion 2 is formed in a substantially tapered shape, and the through hole 5 is formed in the pile side surface portion 2 so that the inside of the pile 3 is By forming it in a substantially hollow shape, it is not necessary to create a preload structure such as embankment 90, etc., and while promoting consolidation of fine-grained land surface 81, it passes through through-hole 5 in pile side face 2 and the inside of the pile 3, the amount of groundwater W flowing into the water 3 can be increased, and the dewatering of the fine-grained ground 81 can be promoted.

  The ground improvement pile 1 to which the present invention is applied, as shown in FIG. 5 (b), is provided in the case where the coarse ground such as sandy soil, gravelly soil, etc. is provided in the coarse ground ground 82 exceeding 50%. As shown in FIG. 10, the groundwater W whose water pressure has increased in the ground 8 is drained to the ground 80 during an earthquake. Here, at the time of an earthquake, the ground water pressure in the ground 8 rises and excess pore water pressure is generated between the soil particles, so that the coarse-grained ground 82 is liquefied. The pile 1 drains the ground water W in the ground 8 to the ground 80, thereby dissipating excess pore water pressure in the ground 8 and preventing liquefaction of the coarse ground ground 82. 82 will improve the ground.

  In the ground improvement pile 1 to which the present invention is applied, the pile side surface portion 2 is formed in a substantially tapered shape so as to expand in the axial direction Y from the distal end portion 1a of the pile in the axial direction Y to the proximal end portion 1b of the pile. By increasing the residual earth pressure P in the ground around the pile, a large pressing force acts on the earth particles of the coarse grain ground 82, and the coarse grain ground even in normal times when no earthquake occurs. 82 compaction is greatly facilitated.

  Furthermore, the ground improvement pile 1 to which the present invention is applied has a through-hole 5 penetrating to the inside 3 of the pile in the pile side surface portion 2, and the pile side surface portion 2 is opened with a predetermined opening ratio. At the time of the earthquake, the groundwater W whose water pressure has increased in the ground 8 passes through the through hole 5 and flows into the pile interior 3, and the water level of the groundwater W flowing into the pile interior 3 gradually rises in the pile interior 3. Then, the groundwater W is drained from the pile interior 3 to the ground 80 at the base end portion 1b of the pile.

  Thereby, the ground improvement pile 1 which applied this invention forms the pile side surface part 2 in a substantially taper shape, and the through-hole 5 is formed in the pile side surface part 2, and the pile inside 3 is formed in a substantially hollow shape. In this way, it is possible to dissipate excess pore water pressure of the coarse-grained ground 82 due to drainage of the groundwater W and compact the coarse-grained ground 82 by increasing the residual earth pressure P in the surrounding ground of the pile. . In the ground improvement pile 1 to which the present invention is applied, the increase of groundwater pressure in the ground 8 is suppressed by remarkably accelerating the compaction of the coarse grain ground 82, and the coarse grain ground 82 has an excess gap. Water pressure is unlikely to occur.

  In the ground improvement pile 1 to which the present invention is applied, the pile side surface portion 2 is formed in a substantially tapered shape, and the through hole 5 is formed in the pile side surface portion 2 so that the inside of the pile 3 is formed in a substantially hollow shape. Compared with the case of draining or compacting gravel drain piles, compaction piles, etc., because it will facilitate compaction of coarse-grained ground bed 82 and drain groundwater W in a single steel pipe pile, etc. As a result, it is possible to reduce the construction cost of ground improvement and shorten the construction period of ground improvement as it is not necessary to create and arrange gravel drain piles, compacted piles, etc. Become.

  The ground improvement pile 1 to which the present invention is applied is such that the pile side surface portion 2 is formed in a substantially tapered shape, so that the through-hole 5 formed in the pile side surface portion 2 is in the axial direction Y as shown in FIG. While being opened downward, the internal cross-sectional area Au of the upper pile interior 3 in the axial direction Y is larger than the internal cross-sectional area Ad of the lower pile interior 3.

  At this time, in the ground improvement pile 1 to which the present invention is applied, since the through-hole 5 formed in the pile side surface portion 2 is opened downward in the axial direction Y, the groundwater W in the ground 8 whose water pressure has increased is generated. It becomes easy to flow into the pile interior 3 through the through hole 5 from below the axial direction Y. Further, in the ground improvement pile 1 to which the present invention is applied, since the internal cross-sectional area Au above the pile interior 3 is larger than the internal cross-sectional area Ad below the pile interior 3, it is lower than the axial center direction Y below. The inside of the pile 3 has a space that is open upward, and the groundwater W that has flowed into the inside of the pile 3 can easily move upward from below.

  Thereby, the ground improvement pile 1 to which the present invention is applied is such that the groundwater W whose water pressure has increased in the ground 8 easily flows into the pile interior 3, and the groundwater W that has flowed into the pile interior 3 is from below the axial direction Y. By being easy to move upward, as shown in FIG. 10, drainage of groundwater W to the ground 80 is promoted, and effective elimination of excess pore water pressure in the coarse-grained ground 82 due to drainage of groundwater W is effective. It becomes possible to carry out.

  As shown in FIG. 12, the ground improvement pile 1 to which the present invention is applied is provided with a heavy material 6 having a specific gravity dw larger than the specific gravity ds of sand around the pile in the pile interior 3. At this time, in the ground improvement pile 1 to which the present invention is applied, the groundwater pressure in the ground 8 rises and an excess pore water pressure is generated between the soil particles at the time of the earthquake. However, since the specific gravity dw of the weight material 6 is larger than the specific gravity ds of the groundwater W and the sand, the weight M of the weight material 6 acting downward in the axial direction Y is The buoyancy F acting upward in the axial direction Y is larger. For this reason, the ground improvement pile 1 to which the present invention is applied does not require the ground improvement pile 1 to reach the supporting ground in the ground 8 and prevents the ground improvement pile 1 from floating on the ground 80 above the ground improvement pile 1. Therefore, it is possible to prevent the ground improvement pile 1 from being lifted from the ground 8 by the dead weight M of the weight material 6 without the need to construct a structure for the purpose.

  Thereby, the ground improvement pile 1 which applied this invention is provided with the weight material 6 of specific gravity dw larger than the specific gravity ds of the surrounding ground of a pile, or the specific gravity of groundwater W in the pile inside 3, At the time of an earthquake, Even if the buoyancy F is applied immediately before the coarse-grained ground 82 is liquefied, the ground improved pile 1 is prevented from lifting from the ground 8 and the ground improved pile 1 is buried in the ground 8. By maintaining the maintained state, it is possible to continue the dissipation of the excess pore water pressure of the coarse-grained ground 82 due to the drainage of the groundwater W.

  The ground improvement pile 1 to which the present invention is applied, as shown in FIG. The weighted material 6 can be provided inside the pile 3. At this time, in the ground improvement pile 1 to which the present invention is applied, since the soil particles S in the ground 8 pass through the through holes 5 formed in the side surface portion 2 of the ground together with the groundwater W, the soil particles S in the ground 8 are piled up. Although it flows into the interior 3, the movement of the soil particles S inside the pile 3 is hindered by the weight 6 when the soil particles S come into contact with the weight 6 inside the pile 3.

  Thereby, the ground improvement pile 1 to which the present invention is applied is such that the weight material 6 having a predetermined particle size adjustment is provided in the pile interior 3 so that the movement of the soil particles S in the ground 8 flowing into the pile interior 3 is heavy. Since only the ground water W is drained up to the ground 80 in a state where the soil particles S in the ground 8 are filtered by being blocked by the material 6, it is necessary to separate the ground water W and the soil particles S. It is possible to reduce the wastewater treatment cost of the groundwater W drained to the ground 80 as not.

  In the ground improvement construction method to which the present invention is applied, the ground improvement pile 1 to which the present invention is applied is provided in the ground 8. The ground improvement method to which the present invention is applied has a pile side surface portion 2 formed in a substantially tapered shape and a pile interior 3 formed in a substantially hollow shape, and a through hole 5 is formed in the pile side surface portion 2. The ground improvement pile 1 is provided in the ground 8 and, as shown in FIG. 5, passes through the through hole 5 and enters the inside 3 of the pile from the fine-grained ground 81 or the coarse-grained ground 82 during a normal or earthquake. The inflowing ground water W is drained to the ground 80.

  The ground improvement method to which the present invention is applied is shown in FIG. 9, particularly when the ground improvement pile 1 is provided on the fine-grained ground 81, without creating a preload structure such as the embankment 90. At the same time that the ground improvement pile 1 having the through hole 5 formed in the portion 2 is driven into the ground 8, the residual earth pressure P of the ground around the pile is increased, and the consolidation and dewatering of the fine-grained ground 81 are started. Therefore, the construction period for ground improvement can be shortened.

  In addition, the ground improvement construction method to which the present invention is applied is shown in FIG. 12, when a heavy material 6 is provided in the pile interior 3, a pile such as a steel pipe pile is driven into the ground 8, and then the pile interior 3. The heavy material 6 may be thrown in, or a pile such as a steel pipe pile may be driven into the ground 8 after the heavy material 6 has been thrown into the pile interior 3. Here, the ground improvement method to which the present invention is applied uses the weight M of the weight material 6 by putting the weight material 6 into the pile interior 3 and then driving a pile such as a steel pipe pile into the ground 8. By placing the steel pipe pile or the like, it becomes possible to improve the workability when placing the steel pipe pile or the like.

  As mentioned above, although the example of embodiment of this invention was demonstrated in detail, all the embodiment mentioned above showed only the example of actualization in implementing this invention, and these are the technical aspects of this invention. The range should not be construed as limiting.

  For example, in the ground improvement pile 1 to which the present invention is applied, the pile side face part 2 such as a steel pipe pile or the like in the axial direction Y may be formed in a substantially tapered shape, and the tip part 1a of the pile such as a steel pipe pile or the like. In addition, either or both of the base end portions 1b of the piles have a straight pipe portion that is formed in a straight shape in the axial direction Y continuously to the pile side surface portion 2 that is substantially tapered. It may be a thing.

1: Ground improvement pile 1a: Tip 1b: Base end 2: Pile side 3: Pile inside 4: Blocking member 5: Through hole 6: Heavy material 8: Ground 8a: Deep side 8b: Surface side 80: Ground 81 : Fine grain ground 82: Coarse grain ground X: Axial axis orthogonal direction Y: Axial direction

Claims (4)

A ground improvement pile provided in the ground,
A pile side surface formed in a substantially tapered shape inclined from one end to the other end in the axial direction, and a pile interior formed in a substantially hollow shape surrounded by the pile side surface,
The pile improvement pile according to claim 1, wherein the pile side surface portion is formed with one or a plurality of through holes so as to penetrate to the inside of the pile. The ground improvement pile according to claim 1, wherein a heavy material using stone or steel slag is provided inside the pile. The ground improvement pile according to claim 1 or 2, wherein said pile side part uses iron material, aluminum material, or vinyl chloride material. A ground improvement method in which ground improvement piles are provided in the ground,
Pile side surface formed in a substantially tapered shape inclined from one end to the other end in the axial direction, and a pile interior formed in a substantially hollow shape surrounded by the pile side surface A ground improvement pile having one or a plurality of through holes formed in the side surface of the pile so as to penetrate to the inside of the pile is provided in the ground, and the pile passes through the through hole at a normal time or during an earthquake. A ground improvement method characterized by draining groundwater flowing into the ground to the ground.

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