CN107254817A - Splice the construction method of widened structure based on assembled template new and old roadbed light soil - Google Patents

Abstract

The invention relates to a construction method for splicing and widening structure of new and old subgrade light soil based on prefabricated formwork, which mainly includes the steps of: construction preparation, laying embankment piles, construction of cast-in-place frame lattice beams and side beams, and installation of T-shaped shear parts And jacking, installation of prefabricated slope slabs, laying of steel mesh, backfilling with light soil, construction of new pavement surface and greening operations inside slope frame beams. The embankment widening structure involved in the present invention has strong shear resistance and good stability at the junction of old and new roadbeds.

Description

Construction method of splicing widening structure of new and old subgrade light soil based on prefabricated formwork

technical field

The invention relates to a construction method for splicing and widening structure of old and new subgrades, in particular to a construction method for splicing and widening structure of old and new subgrades based on assembled templates, which can strengthen the joint strength of new and old subgrades and enhance the overall quality of subgrade and pavement Anti-deformation ability to prevent pavement cracking. It belongs to the field of highway engineering and is suitable for old road reconstruction and expansion projects, especially for high embankment road widening projects in soft soil areas.

Background technique

In recent years, with the rapid development of my country's economy, the traffic volume of highways has been increasing year by year, and the traffic volume of some highways is close to saturated traffic volume. In this regard, in order to meet the growing traffic demand and social development needs, road reconstruction and expansion projects are becoming more and more important. many. Although these projects have high technical and economic value for improving the road grade and road network structure, due to the difference in settlement between the old road embankment and the new road embankment, engineering quality problems such as road surface cracking and local subsidence are prone to occur at the junction of the new and original embankments.

In order to strengthen the combination of new and old road surfaces and effectively control the uneven settlement of the old and new roadbeds, there are many treatment methods. Common ones include excavating steps at the junction of new and original embankments, laying geosynthetic material reinforcement layers, and using lightweight fillers. Engineering and technical measures such as embankment filling. Among them, the excavation steps at the junction of the Xinyuan embankment are excavated within the filler range of the old road embankment. This method is simple in construction and can enhance the connection strength of the junction of the Xinyuan embankment to a certain extent; Reinforced earth embankment is to lay geogrid, steel mesh and other materials within the range of new embankment filling to enhance the integrity and strength of filling; light embankment filling is to use light filler as embankment filling, this method can be used in a large Reduce the weight of the newly filled embankment to a certain extent, and reduce the additional stress of the newly filled embankment on the original embankment foundation. However, for the widening construction of high embankment and subgrade in soft soil areas, the above measures are not enough. When the high embankment and subgrade are widened, the uneven settlement of the old and new subgrade is still relatively obvious, especially on the widening side, the settlement difference of the old subgrade slope is obvious, resulting in a sudden change point, where uneven settlement cracks and sliding shear surfaces are likely to occur. If special measures are not taken, the destructive force of uneven settlement after combined treatment is still relatively large, which needs to be studied and controlled.

Therefore, there is an urgent need to invent a new and old embankment widening structure with high construction efficiency, strong anti-deformation ability, small post-construction settlement and outstanding economic and technical benefits. In the present invention, steps are dug at the junction of the old and new subgrades and the road surface, T-shaped shear parts are installed, embankment piles are laid at the lower part, and prefabricated side slope boards are used for rapid prototyping. According to the current practice, the effect is remarkable. It can strengthen the joint strength of the old and new subgrades, enhance the overall anti-deformation ability of the subgrade and pavement, prevent cracking of the pavement, fast construction speed, and outstanding economic and technical benefits.

Contents of the invention

The purpose of the present invention is to provide a construction method of a roadbed widening structure with high construction efficiency, which can strengthen the strength of the junction of old and new roadbeds, enhance the overall anti-deformation ability of the roadbed and pavement, prevent road surface cracking, and have outstanding economic and technical benefits.

For realizing above-mentioned technical purpose, the present invention adopts following technical scheme:

The construction method of splicing and widening structure of new and old subgrade light soil based on prefabricated formwork is characterized in that the splicing and widening structure of new and old subgrade light soil based on prefabricated formwork mainly includes the original embankment, embankment piles, sash beams, and prefabricated edges. Slope, prefabricated edge beams, T-shaped shear members and light soil; the original embankment slope was excavated into steps, and T-shaped shear members were installed at the steps; embankment piles were installed at the lower part of the new embankment, and the top of the piles was a sash beam. Horizontal strip drainage cushions are arranged at equal intervals inside the sash beams, the ends of the sash beams are connected to the prefabricated side beams, and the prefabricated side slope slabs are installed inside the prefabricated side slabs; the bottom of the prefabricated side slope slabs is anchored to the prefabricated side The tie rods are connected to the jacking on the top of the original embankment; the subgrade of the new embankment is made of light soil, and steel mesh sheets are arranged in the light soil; The main steps of the method are as follows:

1) Construction preparation: draw out the construction area according to the construction drawings, repair the original slope, and excavate the original slope into steps;

2) Laying embankment piles: according to the design drawings, lay powder-sprayed piles at corresponding positions as embankment piles;

3) Construction of cast-in-place frame beams and side beams: After the powder-sprayed piles are piled, the formwork is set on the top of the piles, the frame beams are poured, and horizontal strip drainage cushions are filled in the specified area; after the formwork of the frame beams is removed , hoist the prefabricated side beams in place, and check the axis;

4) Install T-shaped shear parts and jacking: Install T-shaped shear parts layer by layer on the stepped excavation surface of the original embankment from bottom to top. Support, the top support and the T-shaped shear member of the next layer are anchored by screws;

5) Install the prefabricated side slope slab: the prefabricated side slope slab is hoisted in place by a crane, the lower end is embedded in the prefabricated side beam and anchored, and the upper end and the L-shaped jacking are installed with permanent tie rods and temporary support rods;

6) Laying of steel mesh: The steel mesh is paved layer by layer from bottom to top, one end is fixed to the T-shaped shear member, and the other end is placed on the prefabricated slope slab;

7) Backfilling with light soil: After the reinforcement of the reinforcement mesh is completed, pour foam concrete in the area enclosed by the prefabricated slope slab and the excavation surface of the original embankment;

8) Construction of the new pavement surface layer: after the light soil backfill is completed, the new pavement layer is poured, the prefabricated base of the guardrail is embedded in the base, and the guardrail is installed after the maintenance construction is completed;

9) Greening work in the framed beams of the slope: After the above construction is completed, plant grass with foreign soil in the framed beams of the slope.

Further, the surface of the T-shaped shear member has holes, and the soil nails are installed in the reserved holes on the top surface and the side to fix it with the excavation surface of the original embankment, and the upper and lower adjacent T-shaped shear members pass through the overlapping joints The set grooves are interlocked, and all the T-shaped shear members are connected in series by using the through oblique reinforcement.

The sash beam is a cast-in-place reinforced concrete structure, and the sash beam is reserved with an inverted T-shaped hollow groove at the slope toe of the new embankment.

The prefabricated side beam is provided with an oblique cup mouth, the upper part of the oblique cup mouth is an enlarged cup mouth, the bottom of the enlarged cup mouth is pre-embedded with a connecting screw, a drainage channel is reserved in the prefabricated side beam, and the bottom of the prefabricated side beam is provided with a T shape link.

The bottom of the prefabricated slope slab is provided with a wing plate, and screw holes are reserved on the wing plate, and the backfill side of the prefabricated slope slab is uniformly provided with a steel mesh shelving plate and an inner reinforcing rib, and the other side is provided with an outer sash beam.

The jacking bracket has an L-shaped structure, and a filament sleeve is preset on the side, and the jacking bracket is anchored and connected with the lower T-shaped shear member through a screw rod.

A guardrail base connecting screw is pre-embedded in the prefabricated guardrail base.

The present invention has following characteristics and beneficial effect:

(1) The joint between the new and old subgrades is excavated into a step shape, and T-shaped shear members are installed at the steps, supplemented by soil nails, and all the T-shaped shear members are connected into a whole by using the penetrating oblique reinforcement to enhance the stability of the new and old subgrades. Integrity; at the same time, embankment piles are laid under the new embankment, frame beams are set on the top of the embankment piles, and horizontal strip drainage cushions are set to improve the stability of the embankment and reduce the settlement of the embankment after construction.

(2) The slope of the new embankment adopts a prefabricated assembled slope panel, the outer side is lapped to form a grass planting frame, the inner side is evenly equipped with reinforcing ribs and steel mesh shelving plates, and the top of the slope panel is provided with temporary support steel pipes and permanent tie rods. Backfill light soil between old embankments, good stability, high construction efficiency and short construction period.

(3) The new embankment is equipped with a prefabricated guardrail base, and the roadside guardrail is anchored directly through the lower end wing plate and the screw rod in the prefabricated base, and then backfilled with concrete. The construction is fast and convenient.

Description of drawings

Fig. 1 is the schematic diagram of the splicing and widening structure of new and old subgrade light soil based on assembled formwork in the present invention;

Fig. 2 is a structural schematic diagram of the present invention when splicing and widening the light soil of the new and old roadbed based on the assembled formwork without backfilling the light soil;

Fig. 3 is a schematic diagram of the connection between the bottom of the prefabricated slope slab and the edge beam in the present invention;

Fig. 4 is a schematic diagram of guardrail installation in the present invention;

Fig. 5 is a top view of the pile top frame beam structure in the present invention.

In the figure: 1-original roadbed foundation, 2-original roadbed cushion, 3-original roadbed, 4-original road surface, 5-soil nail, 6-jacking fixing screw, 7-filament sleeve, 8-L shape Jacking, 9-T-shaped shear parts, 10-new embankment, 11-permanent tie rod, 12-top filter geotextile, 13-prefabricated guardrail base, 14-guardrail, 15-inner reinforcement rib, 16-edge Slope plants, 17-prefabricated slope slab, 18-reinforced mesh, 19-outer frame beam, 20-light soil, 21-reinforced mesh shelving board, 22-connecting short anchor rod, 23-side beam after pouring Concrete, 24-prefabricated side beams, 25-drainage pipes, 26-embankment piles, 27-through oblique reinforcement, 28-bottom filter geotextiles, 29-horizontal strip drainage cushion, 30-pile top frame beams, 31 -New embankment foundation, 32-temporary brace, 33-fixing nut, 34-embedded screw, 35-wing plate, 36-caulking concrete, 37-T-shaped connecting section, 38-post-cast concrete for guardrail, 39 - guardrail base connecting screw, 40 - guardrail fixing nut, 41 - guardrail bottom flange, 42 - pile top frame beam backfill.

detailed description

In this embodiment, the prefabrication process requirements for prefabricated prefabricated side slope slabs, prefabricated side beams, etc., the construction technical requirements for light soil backfill, the construction process requirements for embankment piles, and the types of plants on the slope will not be described in detail. The implementation method of widening structure construction based on prefabricated template new and old subgrade light soil splicing.

Fig. 1 is a schematic diagram of the splicing and widening structure of new and old subgrade light soil based on prefabricated formwork according to the present invention. Fig. 2 is a schematic diagram of the splicing and widening structure of new and old subgrade light soil based on prefabricated template according to the present invention without backfilling light soil. Fig. 3 is The schematic diagram of the connection between the bottom of the prefabricated side slope slab and the side beam in the present invention, Fig. 4 is a schematic diagram of the installation of the guardrail in the present invention, and Fig. 5 is a top view of the lattice beam structure on the top of the pile in the present invention. Referring to the splicing widening structure of new and old subgrade light soil based on prefabricated formwork shown in Figure 1, it mainly consists of the original embankment, embankment piles 26, frame beams 30, prefabricated side slope slabs 17, prefabricated side beams 24, and T-shaped shear parts 9. Composition of light soil 20 and so on.

The slope of the original embankment is excavated into steps, and T-shaped shear members 9 are arranged at the steps; the surface of the T-shaped shear members 9 has holes, and soil nails 5 are installed in the reserved holes on the top surface and sides to be excavated with the original embankment. The surface is fixed, and the upper and lower adjacent T-shaped shear members 9 are engaged with each other through the tongue and groove provided at the lap, and all the T-shaped shear members 9 are connected in series by using the penetrating oblique rib 27 to form a whole.

The embankment pile 26 is arranged at the bottom of the new embankment, and the pile top is a frame beam 30 . The sash beam 30 is a cast-in-place reinforced concrete structure, and the sash beam 30 is reserved with an inverted T-shaped hollow groove at the slope toe of the new embankment. Horizontal strip-shaped drainage cushions 29 are arranged at equal intervals in the sash beam 30, and the end of the sash beam is connected to the prefabricated side beam 24. The prefabricated side beam 24 is provided with an oblique cup mouth, and the upper part of the oblique cup mouth is an enlarged cup mouth. The connecting screw is pre-embedded at the bottom of the enlarged cup mouth, the drainage channel is reserved in the prefabricated side beam, and the bottom of the prefabricated side beam is provided with a T-shaped connecting section. The prefabricated side slope plate 17 is installed in the prefabricated side beam 24; the bottom of the prefabricated side slope plate 17 is anchored to the prefabricated side beam 24, and the top is connected with the jacking 8 at the top of the original embankment through a permanent tie rod 11; the bottom of the prefabricated side slope plate 17 is provided with a wing Screw holes are reserved on the plate 35 and the wing plate 35, and the backfill side of the prefabricated slope plate 17 is evenly provided with a steel mesh shelving plate 21 and an inner reinforcing rib 15, and an outer sash beam 19 is arranged on the other side. The jacking 8 has an L-shaped structure, and the side is preset with a filament casing 7, and the jacking 8 is anchored and connected with the lower T-shaped shear member 9 through a screw.

The lower part of the new embankment 10 is light soil 20, and the steel mesh sheet 18 is arranged in the light soil 20; the top of the light soil is a new pavement layer, and a prefabricated guardrail base 13 is arranged in the new pavement layer. A guardrail base connecting screw 39 is pre-embedded in the prefabricated guardrail base 13 .

The above-mentioned construction method based on the prefabricated template new and old subgrade light soil splicing widening structure, the main steps are as follows:

1) Construction preparation: draw out the construction area according to the construction drawings, repair the original slope, and excavate the original slope into steps;

2) Embankment stakes are driven: according to the design drawings, powder-sprayed piles are set at corresponding positions as embankment stakes 26;

3) Construction of cast-in-place frame beams and side beams: After the powder-sprayed piles are piled, the formwork is set up on the top of the piles, the frame beams 30 are poured, and horizontal strip drainage cushions 29 are filled in the specified area; After molding, hoist the prefabricated side beam 24 in place, and check the axis;

4) Install T-shaped shear parts and jacking: Install T-shaped shear parts 9 layer by layer on the stepped excavation surface of the original embankment from bottom to top. T-shaped shear parts 9 are anchored to the original embankment with soil nails 5, and installed L-shaped jacking 8, and the jacking 8 and the T-shaped shear member 9 of the next layer are anchored by screws;

5) Install the prefabricated side slope board: the prefabricated side slope board 17 is hoisted in place by a crane, the lower end is embedded in the prefabricated side beam 24 and anchored, and the permanent tie rod 11 is installed between the upper end and the L-shaped jacking 8 and a temporary support rod 32 is erected ;

6) Lay the steel mesh: the steel mesh 18 is paved layer by layer from bottom to top, one end is fixed to the T-shaped shear member 9, and the other end is placed on the prefabricated slope slab;

7) Backfilling with light soil: After the reinforcement of the reinforcement mesh 18 is completed, pour foam concrete in the area enclosed by the prefabricated side slope slab and the excavation surface of the original embankment;

8) Construction of new pavement surface layer: after the light soil backfill is completed, pour a new pavement layer, and prefabricate the base 13 of the guardrail embedded in the base, and install the guardrail 14 after the maintenance construction is completed;

9) Greening work in the framed beams of the slope: After the above construction is completed, plant grass with foreign soil in the framed beams of the slope. The specific construction steps are as follows:

Plan the construction area before the construction, and repair the slope of the original embankment, excavate the original slope into a step shape, the step width is 1000mm, and the inclination is 3%; after the excavation, arrange the pile driver to enter the site, and accurately measure the axis and pile position , and calibrated with bamboo sticks or steel bars, the diameter of embankment pile 26 (powder spray pile) is 600mm, and the pile length is 12000mm.

After the embankment pile 26 is completed, re-level the site, bind the frame beam steel bars, set up the formwork, pour C25 concrete, and maintain to form the frame beam foundation. The sash beam 30 has a specification of 400mm×400mm and a height of 80mm. A T-shaped hollow groove is reserved on the sash beam at the end of the slope foot, with a size of 300mm×200mm and a width of 50mm; and a horizontal drainage strip with a width of 300mm is set every 10m , the drainage belt is mainly composed of gravel, and the rest of the frame beams are backfilled with foundation soil.

After the formwork of the sash beam is removed, the prefabricated side beam 24 is hoisted in place, the T-shaped connecting section of the prefabricated side beam 24 is embedded in the reserved groove of the sash beam, and the axis of the side beam is checked to ensure that the error is controlled within a reasonable range. Among them, the prefabricated side beam 24 has a specification of 600mm×600mm, and there is a 40° oblique cup mouth inside, the cup mouth is 150mm wide, and the upper part of the oblique cup mouth is an enlarged cup mouth. A connecting screw with a diameter of 8mm is embedded for the bottom, and a drainage channel with a diameter of 100mm is reserved in the prefabricated side beam.

After the side beams are hoisted, T-shaped shear members 9 are installed layer by layer on the stepped excavation surface of the original embankment from bottom to top. The shear member 9 is anchored with the original embankment by soil nails 5, and the top layer is equipped with an L-shaped jacking 8 with a width of 600mm, a height of 400mm, and a wall thickness of 20mm. Holder side wall is welded the filament sleeve pipe 7 of internal diameter 16mm.

The prefabricated side slope slab 17 is hoisted in place by a crane, the lower end is embedded in the prefabricated side beam 24 and anchored, and a permanent tie rod 11 with a diameter of 16 mm is installed between the upper end and the L-shaped jacking bracket and a temporary support rod 32 is erected; The sheet 18 is paved layer by layer from bottom to top, one end is fixed to the T-shaped shear member 9, and the other end rests on the prefabricated slope slab. After the reinforcement of the steel mesh is completed, the foam concrete with a strength of C3.0 is poured in the area enclosed by the prefabricated slope slab and the excavation surface of the original embankment.

After the light soil backfill is completed, a new pavement layer is poured, and a prefabricated concrete guardrail base 13 with a specification of 150mm×150mm×120mm is embedded in the base every 3000mm. The reserved hole is anchored with the pre-embedded screw 39 of the guardrail base, and then refilled with C20 concrete to seal the groove.

After the above construction is completed, grass will be planted with foreign soil in the frame beams of the slope.

Claims (7)

1. The construction method based on the splicing and widening structure of the new and old subgrade light soil of the prefabricated formwork is characterized in that, the splicing and widening structure of the new and old subgrade light soil based on the prefabricated template mainly includes the original embankment, embankment piles (26), frame Grid beams (30), prefabricated side slope slabs (17), prefabricated side beams (24), T-shaped shear members (9) and light soil (20); the original embankment slope is excavated into steps, and the steps are set T-shaped shear parts (9); embankment piles (26) are arranged at the lower part of the new embankment, and the top of the piles is a sash beam (30). The end of the grid beam is connected with the prefabricated side beam (24), and the prefabricated side slope plate (17) is installed in the prefabricated side beam (24); The pull rod (11) is connected with the jacking (8) at the top of the original embankment; the subgrade of the new embankment (10) is light soil (20), and the steel mesh sheet (18) is arranged in the light soil (20); the top of the light soil It is a new pavement layer, and a prefabricated guardrail base (13) is arranged in the new pavement layer. The main steps of the construction method are as follows: 1) Construction preparation: draw out the construction area according to the construction drawings, repair the original slope, and excavate the original slope into steps; 2) driving embankment piles: according to the design drawings, setting powder-sprayed piles at corresponding positions as embankment piles (26); 3) Construction of cast-in-place frame beams and side beams: after the powder-sprayed piles are piled, formwork is placed on the top of the piles, the frame beams (30) are poured, and horizontal strip drainage cushions (29) are filled in the specified area; After the formwork of the sash beam is removed, the prefabricated side beam (24) is hoisted in place, and the axis is checked; 4) Install T-shaped shearing parts and jacking: Install T-shaped shearing parts (9) layer by layer on the stepped excavation surface of the original embankment from bottom to top, and T-shaped shearing parts (9) use soil nails (5) and The original embankment is anchored, and an L-shaped jacking (8) is installed on the top layer, and the jacking (8) and the T-shaped shear member (9) of the next layer are anchored by screws; 5) Install the prefabricated side slope slab: The prefabricated side slope slab (17) is hoisted in place by a crane, the lower end is embedded in the prefabricated side beam (24) and anchored, and the upper end and the L-shaped jacking (8) are installed with a permanent tie rod ( 11) and set up temporary struts (32); 6) Lay the reinforcement mesh: the reinforcement mesh (18) is paved layer by layer from bottom to top, one end is fixed to the T-shaped shear member (9), and the other end is placed on the prefabricated slope slab; 7) Backfilling with light soil: after the reinforcement of the reinforcement mesh (18) is completed, pour foam concrete in the area enclosed by the prefabricated side slope slab and the excavation surface of the original embankment; 8) Construction of new pavement surface layer: pouring new pavement layer after backfilling with light soil, prefabricated base (13) for guardrails embedded in the base, and installing guardrails (14) after the maintenance construction is completed; 9) Greening work in the framed beams of the slope: After the above construction is completed, plant grass with foreign soil in the framed beams of the slope. 2. The construction method according to claim 1, characterized in that the surface of the T-shaped shear member (9) has holes, and the soil nails (5) and the original embankment are installed in the reserved holes on the top surface and sides. The excavation surface is fixed, and the upper and lower adjacent T-shaped shear members (9) are engaged with each other through the tongue and groove provided at the lap joint, and all the T-shaped shear members (9) are connected in series into a whole by using penetrating oblique ribs (27). 3. The construction method according to claim 1, characterized in that the sash beam (30) is a cast-in-place reinforced concrete structure, and the sash beam (30) is reserved with an inverted T shape at the slope foot of the new embankment. Hollow groove. 4. The construction method according to claim 1, characterized in that the prefabricated side beam (24) is provided with an oblique cup mouth, the upper part of the oblique cup mouth is an enlarged cup mouth, and the bottom of the enlarged cup mouth is pre-buried and connected screw, a drainage channel is reserved in the prefabricated side beam, and a T-shaped connecting section is provided at the bottom of the prefabricated side beam. 5. construction method according to claim 1, is characterized in that described prefabricated slope plate (17) bottom is provided with wing plate (35), reserves screw hole on the wing plate (35), prefabricated side slope plate ( 17) On the backfill side, the reinforcement mesh shelving plate (21) and the inner reinforcement rib (15) are evenly arranged, and the outer sash beam (19) is arranged on the other side. 6. The construction method according to claim 1, characterized in that the jacking (8) has an L-shaped structure, the side is preset with a filament sleeve (7), and the jacking (8) is connected with the lower T-shaped The shear member (9) is anchored and connected. 7. The construction method according to claim 1, characterized in that a guardrail base connecting screw (39) is pre-embedded in the prefabricated guardrail base (13).