Sheet pile ribbed structures and their construction methods in a weakly disturbed environment

Abstract

This invention discloses a novel sheet pile-type roadbed widening structure for use in low-disturbance environments, belonging to the field of roadbed widening technology. The structure includes concrete columns and steel sheet piles, horizontally fixed together by tie rods. Internal filling is then carried out to integrate the new and existing roadbeds. Corrugated pipes encase the tie rods to prevent corrosion. The corrugated pipe design and grouting measures ensure a tighter contact between the anchor structure and the filling material, resulting in better corrosion resistance and further improving structural stability. This invention also provides a construction method for this structure, effectively solving the problem of existing roadbed widening relying on on-site construction. Factory prefabrication reduces costs, increases standardization, and accelerates field construction, minimizing the impact on existing roadbeds and improving the stability of the widened roadbed structure, thus avoiding instability caused by uneven settlement between the new and existing roadbeds.

Description

Technical Field

[0001] This invention relates to the field of roadbed widening technology, specifically to a novel sheet pile widening structure and its construction method under a low-disturbance environment. Background Technology

[0002] With the rapid increase in my country's total transportation volume, many operating railways, which have not fully considered sustainable development and balanced regional development, suffer from insufficient transport capacity. Therefore, it is necessary to accelerate the expansion of operating railway capacity. Currently, adding lines is the most effective way to improve the current transport capacity of operating railways and supplement short- and long-term transport capacity.

[0003] However, the differential deformation and stability issues caused by widening in the track extension project have become major challenges and prominent contradictions in railway capacity expansion and renovation. Furthermore, conventional widening subgrade structures suffer from problems such as large land occupation, significant impact on existing subgrades, long construction periods, and large differential settlement between the new and existing subgrades. To address the need for simple, short-term, and minimally impactful widening section construction for existing lines, a novel sheet pile widening structure and construction method for low-disturbance environments are urgently required to solve these problems. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] In view of the shortcomings of the existing technology, the present invention provides a novel sheet pile-type backing structure for weak disturbance environment to solve the problems of (1) the large slope of the traditional backing structure to maintain stability, which leads to a large land area and large-scale excavation during on-site construction, which reduces the stability of the existing roadbed. The present invention also provides a construction method for the backing structure to solve the problems of (2) long on-site construction time, which affects railway operation, and instability caused by uneven settlement and lateral deformation of the foundation.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A novel sheet pile backfill structure for use in low-disturbance environments includes concrete columns and steel sheet piles. A retaining plate is installed on the inner side of the concrete column. The steel sheet piles are statically pressed into the existing roadbed. The concrete column and steel sheet piles are laterally connected by tie rods. Corrugated pipes are fitted over the tie rods. Short piles are installed on the outer side of the concrete column, and long piles are installed on the inner side. A crushed stone cushion layer is installed on the top of the long piles, and a concrete hardening layer is installed on the top of the short piles. The bottom of the steel sheet piles is embedded in the top surface of the existing roadbed crushed stone cushion layer. The retaining plate and the existing roadbed are filled with a filler layer, and a waterproof geotextile is installed on the top of the filler layer. Two anchor holes are vertically arranged in the cantilever section of the concrete column, and corresponding pre-drilled holes are provided on the steel sheet piles at the same height as the anchor holes.

[0009] As a further description of the above technical solution:

[0010] The length of the cantilever section of the concrete column shall not exceed 1 / 3 of its total length, and the length of the anchorage section shall not be less than 2 / 3 of its total length. The tie rods fix the concrete column and the sheet pile through the reserved holes and the anchor cable holes.

[0011] As a further description of the above technical solution:

[0012] The distance from the anchor cable hole at the top to the top of the concrete column is 1 / 3 of the length of the cantilever section of the concrete column. The sheet pile is Z-shaped, and the tie rods are threaded steel bars, with two bundles of threaded steel bars arranged in each tie rod.

[0013] As a further description of the above technical solution:

[0014] The diameter of the anchor cable hole is 100mm, and a 25×30mm bearing platform is set on the outside of the anchor cable hole. The diameter of the reserved hole is 150mm. The diameter of the corrugated pipe is 50mm, the inner diameter is 62mm, and the outer diameter is 82mm. The tie rod is made of threaded steel with a diameter of 20mm, and two layers of tie rods are arranged vertically. The inside of the corrugated pipe is also grouted.

[0015] As a further description of the above technical solution:

[0016] The hardened concrete layer is made of C30 concrete, with a thickness of not less than 300mm and a width of 1.5m. An expansion joint is set every 5m. The thickness of the crushed stone mattress layer is 40cm.

[0017] As a further description of the above technical solution:

[0018] The retaining plate is prefabricated, with a width × height of 0.3 × 0.5 m. The length is determined according to the spacing of the concrete columns, and the overlap length on the concrete columns is not less than 0.5 m. It is equipped with internal reinforcing steel bars.

[0019] As a further description of the above technical solution:

[0020] The concrete columns are cuboids with a cross-sectional dimension of 2×3m. During construction, they are reinforced with internal steel bars, and the formwork is erected and poured on site. The spacing between the concrete columns along the route is 5-7m.

[0021] As a further description of the above technical solution:

[0022] Before laying the fill layer, the existing roadbed needs to be excavated into a stepped shape, with a step height of 0.5m and a width of 0.75m. A geogrid with a single width of 2.0m is also installed in the fill layer.

[0023] As a further description of the above technical solution:

[0024] A top filler is installed on top of the waterproof geotextile, and the waterproof geotextile completely covers the filler layer. When the waterproof geotextile needs to be overlapped, an adhesive material with waterproof effect is used for the overlap, and the overlap width must exceed 10cm.

[0025] This invention also provides a construction method for a novel sheet pile-type ribbed structure in a weakly disturbed environment, comprising the following steps:

[0026] S1. Preparation: The preparation work is divided into the prefabrication stage and the on-site treatment stage. The prefabrication stage is carried out in the factory. The steel frame is rolled according to the drawings. After the template is coated with release agent, it is made into a mold. After the embedded parts are placed, the concrete is poured. After the concrete hardens, the mold is removed and the retaining plate is prepared. The on-site treatment stage requires on-site construction in conjunction with the design drawings. It mainly includes leveling the foundation, excavation of concrete column foundations, excavation of existing roadbed, and construction of composite foundations. The construction of composite foundations includes the construction of long and short piles. The main process is: pile position layout → drilling rig positioning → drilling rig hole formation → hole cleaning and installation of steel cage → grouting and pipe pulling → grouting pile formation. The construction sequence of long and short piles is to advance from the center of the line to both sides in sequence, and the skip pile method is used to avoid breaking adjacent piles.

[0027] S2. Installation of steel sheet piles and pouring of concrete columns: Install steel sheet piles on site according to the design drawings. The overall inclination ratio of the steel sheet piles during construction is about 1:20. The bottom of the steel sheet piles should be inserted to the top surface of the existing roadbed gravel cushion layer. Tie the steel frame of the concrete column according to the design drawings and pour the concrete.

[0028] S3. Construction of temporary prestressed anchors, crushed stone cushion layer and concrete hardening layer: After the above steps are completed, the crushed stone cushion layer of the filling area is constructed. During construction, the existing crushed stone cushion layer of the roadbed is broken to connect the new roadbed cushion layer with the existing roadbed cushion layer; concrete is poured integrally at the top of the short pile to form a concrete hardening layer; temporary prestressed anchors are installed in the anchor cable holes at the top of the concrete column to make the steel sheet pile and the concrete column tensile;

[0029] S4. Interlocking construction of fill layer, retaining plate, tie rod, and corrugated pipe: Prefabricated retaining plates are transported to the site, leveled, and laid out. The retaining plates are then hoisted by cranes with steel cables installed on both sides. After placement, the roadbed fill material is poured in layers. Manual leveling is performed first, followed by mechanical compaction. During filling, the retaining plate must be at least one layer higher than the filling position, up to the top. During compaction, compaction proceeds sequentially from the concrete column position inwards. When compaction reaches the lower anchor hole position, corrugated pipes are installed and the lower tie rods are pre-tensioned. Then, the upper temporary prestressed anchors are released, and compaction continues until the filling position reaches the upper anchor hole position. Corrugated pipes are then installed and the upper tie rods are pre-tensioned, continuing construction until the filling work is complete. Geogrids are installed after filling to the appropriate position.

[0030] S5. Waterproof geotextile construction: When the filling reaches its designed position, place the waterproof geotextile, and then continue laying to complete the construction.

[0031] (III) Beneficial Effects

[0032] Due to the adoption of the above technical solution, the beneficial effects of this application are:

[0033] (1) By installing steel sheet piles, the disturbance to the existing line during the construction of the new line is reduced, allowing the existing line to continue operating even during the construction of the new line. Concrete columns and steel sheet piles are installed, horizontally fixed together by tie rods, and filled internally, forming a unified structure between the new and existing roadbeds. The horizontal tension ensures that the structure, especially the tie rods, only bears lateral tension, preventing damage caused by tilting of the tie rods. The tie rods are encased in corrugated pipes to prevent corrosion, and the corrugated pipe design and grouting measures ensure a tighter contact between the anchor structure and the filling material, resulting in better corrosion resistance and further improving structural stability.

[0034] (2) Setting up short piles, long piles, and geogrids can effectively avoid foundation damage caused by uneven settlement. At the same time, the concrete columns and retaining wall structure reduce the slope length and the land area occupied. By forming a reinforced structure with tie rods, the upper fill material is constrained and its own energy dissipation effect is achieved, which can improve the dynamic characteristics of the slope structure. Moreover, the soil in the reinforced material area forms a retaining wall-like integral structure under the action of lateral constraint force, ensuring the structural stability.

[0035] (3) The structure and construction method provided by the present invention effectively solve the problem of existing roadbed widening relying on on-site construction. By factory prefabrication, the cost is reduced, the standardization is improved, the speed of field construction is increased, the impact on the existing roadbed is minimized, the stability of the roadbed widening structure is improved, and the instability problem caused by uneven settlement between the new and existing roadbeds is avoided. Attached Figure Description

[0036] Figure 1 This is a schematic cross-sectional view of the overall structure of the present invention;

[0037] Figure 2 This is a schematic diagram of the plan layout of the steel sheet piles of the present invention;

[0038] Figure 3 This is a schematic diagram of the steel sheet pile of the present invention;

[0039] Figure 4 This is a schematic diagram showing the positions of the pressure-bearing platform and anchor cable holes in this invention;

[0040] Figure 5 This is a schematic diagram of the structure and arrangement of the isolation fence of the present invention;

[0041] Figure 6 This is a schematic diagram of the planar layout of the concrete columns of the present invention.

[0042] In the diagram: 1. Concrete column; 1-1. Bearing platform; 1-2. Anchor cable hole; 2. Crushed stone cushion layer; 3. Steel sheet pile; 4. Tie rod; 5. Corrugated pipe; 6. Concrete hardened layer; 6-1. Expansion joint; 7. Waterproof geotextile; 8. Upper filling material; 9. Retaining plate; 10. Short pile; 11. Filling material layer; 12. Long pile. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Please see Figure 1-6A novel sheet pile backfill structure for use in low-disturbance environments comprises concrete columns 1 and steel sheet piles 3. A retaining plate 9, prefabricated and directly installed on-site, is installed inside the concrete columns 1, reducing the construction period and ensuring consistent quality. The retaining plate 9 is preferably 0.3m wide x 0.5m high; this suitable size facilitates casting, loading, unloading, and transportation. Determining the optimal size while ensuring strength also benefits the filling of the fill layer 11. The length is determined based on the spacing of the concrete columns 1; the length is determined for prefabrication after the project plan is finalized. The overlap length on the concrete columns 1 is not less than 0.5m, and internal reinforcing steel is provided; the appropriate overlap length also improves stability. The steel sheet piles 3 are statically pressed into the existing roadbed, avoiding damage and maximizing its stability. Furthermore, the installation of the steel sheet piles 3 allows construction to proceed without affecting the operation of the existing railway line. The concrete column 1 and the steel sheet pile 3 are laterally connected by tie rods 4, forming a unified structure between the concrete column 1 and the steel sheet pile 3, thus integrating the new and existing roadbeds and maximizing stability. The lateral restraint provided by the tie rods 4 also prevents lateral displacement of the concrete column 1. A corrugated pipe 5 is fitted over the tie rod 4 to prevent corrosion of the metal material. The shape of the corrugated pipe 5 ensures maximum contact and fit with the fill material, further enhancing stability.

[0045] The outer side of concrete column 1 is a passive zone and requires reinforcement. Short piles 10 are installed in the passive zone to prevent the collapse of the newly constructed roadbed. The pile diameter and spacing can be determined based on the site soil conditions, and the pile length is generally not less than 1 / 3 of the anchorage section of concrete column 1. Long piles 12 are installed on the inner side of concrete column 1. Due to the different settlement levels between the new and existing roadbeds, the long piles 12 can prevent significant settlement of the new roadbed. A crushed stone cushion layer 2 is installed on top of the long piles 12. During construction, the existing crushed stone cushion layer of the roadbed is broken, and the crushed stone cushion layer 2 is re-laid up to the concrete column 1. A concrete hardening layer 6 is installed on top of the short piles 10. The concrete hardening layer 6 is preferably made of C30 concrete, with a thickness preferably not less than 300mm and a width preferably 1.5m. It fills the gaps between concrete columns 1. An expansion joint 6-1 is preferably installed every 5m. The thickness of the crushed stone cushion layer 2 is preferably 40cm. The appropriate size design satisfies both structural stability and reduces construction costs. The bottom of the sheet pile 3 is embedded in the top surface of the existing roadbed gravel cushion layer, and the retaining plate 9 is filled with a filler layer 11 to form an integral roadbed structure. A waterproof geotextile 7 is installed on the top of the filler layer 11 to prevent erosion of the new roadbed by rainfall and other factors, which could threaten structural stability. The cantilever section of the concrete column 1 has two anchor holes 1-2 in the vertical direction, and a corresponding reserved hole is set on the sheet pile 3. The reserved hole is at the same height as the anchor hole 1-2. By setting the anchor hole 1-2 and the reserved hole at the same height, the difficulty of the construction process is reduced, and the tie rod 4 is only subjected to the compressive force of the lateral displacement of the filler, avoiding the large tensile force on the tie rod 4, which could affect the structural stability.

[0046] In the embodiments of this application:

[0047] Please see Figure 1 and 5 The cantilever section of the concrete column 1 shall not exceed 1 / 3 of its total length, and the anchorage section shall not be less than 2 / 3 of its total length. Maintaining a relatively long anchorage section buried underground can minimize the risk of tilting of the concrete column 1 under stress. The tie rods 4 fix the concrete column 1 and the sheet pile 3 through the reserved holes and anchor cable holes 1-2.

[0048] In a preferred embodiment, the anchor holes 1-2 located at the top are one-third the length of the cantilever section of the concrete column 1 from the top of the concrete column 1. The sheet piles 3 are Z-shaped to distribute the lateral compression of the sheet piles 3 by the existing roadbed. The sheet piles 3 are preferably of the WRZ18-635 type, and the overall inclination ratio during construction is approximately 1:20. The tie rods 4 are preferably threaded steel bars, with two bundles of threaded steel bars arranged on each tie rod 4. This avoids the damage caused by the instability of one bundle.

[0049] Please see Figure 2In one embodiment, the sheet pile 3 is spliced ​​from multiple modules, with the splice joints forming hook-shaped fasteners, which can resist a certain amount of deformation and maintain the stability of the foundation to the maximum extent.

[0050] In the embodiments of this application:

[0051] Please see Figure 1 and 6 The diameter of the anchor cable hole 1-2 is preferably 100mm. A bearing platform 1-1 of preferably 25×30mm is set on the outside of the anchor cable hole 1-2. The center distance between the upper and lower anchor cable holes 1-2 is about 2m. The diameter of the reserved hole is preferably 150mm. The diameter of the corrugated pipe 5 is preferably 50mm, the inner diameter is preferably 62mm, and the outer diameter is preferably 82mm. The tie rod 4 uses threaded steel with a diameter preferably 20mm, so that the two bundles of threaded steel can be completely wrapped by the corrugated pipe 5 without leaving too much space. Two layers of tie rods 4 are arranged vertically. During construction, the corrugated pipe 5 is filled inside the filler layer 11. After construction is completed, grout is injected into the interior of the corrugated pipe 5 through the grouting hole reserved in the concrete column 1. Through grouting, the threaded steel and the corrugated pipe 5 are in close contact, which improves the strength and avoids corrosion of the threaded steel caused by oxygen or moisture in the air. Concrete column 1 is a cuboid with a cross-sectional dimension of 2×3m according to the "Code for Design of Railway Subgrade Retaining Structure". During construction, it is reinforced with internal reinforcing steel bars. The quantity and location are determined based on the site conditions. The formwork is erected and the concrete is poured on site. The spacing of concrete columns 1 along the railway line is 5-7m.

[0052] In the embodiments of this application:

[0053] Please see Figure 1Before laying fill layer 11, the existing roadbed needs to be excavated into a stepped shape, with a step height of 0.5m and a width of 0.75m. A geogrid with a single width of 2.0m is also installed in fill layer 11. The geogrid is placed at the connection between the new and existing roadbeds in the stepped shape to strengthen the connection between the new and existing roadbeds. The construction process of fill layer 11 is to first spread and then compact. During construction, prestressed anchor rods are temporarily pre-stretched in the upper anchor cable holes 1-2 and the reserved holes to form a box structure before filling. During filling, retaining boards 9 are placed layer by layer, ensuring they are at least one layer higher than the filling position. Compaction is performed simultaneously with filling. Geogrids are placed at appropriate locations. When filling reaches the lower anchor holes 1-2 and pre-reserved holes, corrugated pipes 5 are installed and the lower tie rods 4 are pre-tensioned. The upper prestressed anchors are then removed. This removal facilitates upper filling construction and ensures that the lower layer has achieved tensile stability, preventing upper tilting. Near the top of the filling, waterproof geotextile 7 is laid, with upper fill material 8 placed on top. The waterproof geotextile 7 completely covers the fill material layer 11. When overlapping is necessary, a waterproof adhesive material, such as silicone waterproof coating, is used. The overlap width must exceed 10cm. This overlapping completely isolates the upper water flow from the new roadbed, minimizing infiltration and maintaining roadbed stability.

[0054] This application also provides a construction method for a novel sheet pile-type ribbed structure in a weakly disturbed environment, the steps of which are as follows:

[0055] S1. Preparatory Work: The preparatory work is divided into the prefabrication stage and the on-site treatment stage. The prefabrication stage is carried out in the factory. The steel frame is rolled according to the drawings. After the template is coated with a release agent, it is made into a mold. After the embedded parts are placed, the concrete is poured. After the concrete hardens, the mold is removed and the retaining plate 9 is prepared. The on-site treatment stage requires on-site construction in conjunction with the design drawings. It mainly includes leveling the foundation of the widened foundation, excavation of the foundation of the concrete column 1, construction of the composite foundation, and excavation of the existing roadbed. The leveling of the foundation of the widened foundation and the construction of the composite foundation are completed before the construction of the crushed stone cushion layer 2. When excavating the existing roadbed, steps with a height of 0.5m and 0.75m are excavated in conjunction with the existing roadbed slope, and the installation trench is excavated at the location of the tie rod 4 to prepare for the subsequent installation of the anchor rod, so as to ensure the connection between the new widened roadbed and the existing roadbed. The composite foundation construction includes the construction of short piles 10 and long piles 12. Its main process is: pile position layout → drilling rig positioning → drilling rig hole formation → hole cleaning and installation of steel cage → grouting and pipe pulling → grouting pile formation. The specific requirements are as follows:

[0056] (1) Staking out the pile positions. First, a total station is used to determine the precise positions of the longitudinal control piles on both sides of the roadbed.

[0057] (2) Drilling Rig Positioning. When positioning the drilling rig, ensure that the outer edge of the drill tower sheave, the drill bit tip, and the pile location are aligned. Ensure the drill rod is perpendicular to the ground. Only after aligning the drill bit tip with the pile location can the drilling rig be fixed in place. Adjust the hydraulic feet of the drilling rig to ensure it remains level. The allowable deviation of the drill rod's verticality should be controlled within 1%.

[0058] (3) Drilling. During drilling, avoid damage to the drill bit or drill rod, and also avoid tilting of the hole. After drilling is completed, clean the residue in the hole to ensure that the bearing capacity of the pile meets the requirements after pile formation.

[0059] (4) Grouting and pipe pulling. The mixture can only be pumped and grouted after drilling is completed.

[0060] (5) Pile Casting. After casting is completed, the drilling tools are removed from the borehole opening to prevent heavy machinery such as vehicles from running over and crushing the pile top. Before the initial setting of the pile, the pile head is very fragile and easily damaged, so effective protective measures need to be taken to avoid damage to the pile head.

[0061] (6) Construction sequence. The construction sequence proceeds from the center of the line to both sides, and the skip pile method is used to avoid breaking adjacent piles.

[0062] S2. Installation of steel sheet piles 3 and pouring of concrete columns 1: Install steel sheet piles 3 on site according to the design drawings. During the construction of steel sheet piles 3, the overall inclination ratio is about 1:20. The bottom of steel sheet piles 3 should be inserted to the top surface of the existing roadbed gravel cushion layer to ensure the stability and bending resistance of steel sheet piles 3. The steel reinforcement frame of concrete column 1 is tied according to the design drawings and concrete is poured. Anchor holes 1-2 and bearing platforms 1-1 are reserved at the design positions to ensure smooth subsequent construction.

[0063] S3. Construction of temporary prestressed anchors, crushed stone cushion layer 2 and concrete hardening layer 6: After the above steps are completed, the crushed stone cushion layer 2 in the filling area is constructed. During construction, the existing crushed stone cushion layer of the roadbed is broken to connect the new roadbed cushion layer with the existing roadbed cushion layer. The thickness of the cushion layer is not less than 40cm. Concrete is poured on the top of the short pile 10 to form the concrete hardening layer 6. The hardening layer is 2m wide and 0.3m thick, and fills the gap of the concrete column 1. An expansion joint is set every 5m along the line direction. Temporary prestressed anchors are installed in the anchor holes 1-2 at the top of the concrete column 1 so that the steel sheet pile 3 and the concrete column 1 are under tension to form a hollow box structure that can be filled.

[0064] S4, Interleaved Construction of Fill Layer 11, Retaining Plate 9, Tie Anchor 4, and Corrugated Pipe 5: The prefabricated retaining plate 9 is transported to the site, leveled, and laid out. The retaining plate 9 is then hoisted by a crane with steel cables installed on both sides. After placement, the subgrade fill material is poured in layers, each layer being 0.5m high. The layers are first manually leveled, then mechanically compacted to ensure the compaction degree meets the relevant requirements of the "Railway Subgrade Design Code." During filling, the retaining plate 9 must be at least one layer higher than the filling position, up to the top, before compaction. The concrete is compacted sequentially from the position of the concrete column 1 inwards. When the compaction reaches the position of the lower anchor cable hole 1-2, the corrugated pipe 5 is installed and the lower tie rod 4 is pre-tensioned. Then the upper temporary prestressed anchor rod is loosened, and the compaction work continues. Geogrid is installed at the appropriate position until the filling position reaches the position of the upper anchor cable hole 1-2. Then the corrugated pipe 5 is installed and the upper tie rod 4 is pre-tensioned. Construction continues until the filling work of the fill layer 11 is completed. The various tasks are carried out alternately and in sections to save the construction period and maximize the utilization of machinery and manpower.

[0065] It should be noted that if the filling material is a castable material, such as concrete, only the upper tie rod 4 needs to be installed. Filling can continue until the geogrid is installed. When the filling reaches the position of the geogrid, the geogrid is installed. When the filling reaches the position of the upper anchor hole 1-2, the corrugated pipe 5 is installed and the upper tie rod 4 is pre-tensioned. The lower tie rod 4 is not installed.

[0066] S5. Waterproof geotextile 7 construction: When the filling reaches its designed position, place the waterproof geotextile 7. The waterproof geotextile 7 should be fully laid to completely cover the filling layer 11. When the waterproof geotextile 7 needs to be overlapped, a waterproof adhesive material, such as silicone waterproof coating, should be used for the overlap. The overlap width should exceed 10cm. Then continue to lay the upper filling layer 8 and complete the construction.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sheet pile backfill structure under a weak disturbance environment, comprising a concrete column (1) and steel sheet piles (3), wherein a retaining plate (9) is provided on the inner side of the concrete column (1), and the steel sheet piles (3) are statically pressed into the interior of the existing roadbed. The concrete column (1) and the steel sheet piles (3) are laterally connected by tie rods (4), and a corrugated pipe (5) is sleeved on the outside of the tie rods (4). Short piles (10) are provided on the outside of the concrete column (1), and long piles (12) are provided on the inside. A crushed stone cushion layer (2) is provided on the top of the long piles (12), and the top of the short piles (10) is... The section is equipped with a concrete hardening layer (6). The bottom of the steel sheet pile (3) is embedded into the top surface of the existing roadbed gravel cushion layer. The retaining plate (9) is filled with a filling layer (11) between it and the existing roadbed. A waterproof geotextile (7) is installed on the upper part of the filling layer (11). The cantilever section of the concrete column (1) is provided with two anchor holes (1-2) in the vertical direction. A reserved hole is provided on the corresponding position of the steel sheet pile (3). The reserved hole is at the same height as the anchor hole (1-2). Before the filling layer (11) is laid, the existing roadbed needs to be excavated and excavated into a stepped shape with a step height of 0.5 m and a width of 0.75 m. A placement groove is excavated at the position of the tie rod (4) for subsequent anchor installation. A geogrid is also installed in the filling layer (11) with a single width of 2.0 m.

2. The sheet pile-type backing structure under weak disturbance environment as described in claim 1, characterized in that: The length of the cantilever section of the concrete column (1) shall not exceed 1 / 3 of its total length, and the length of the anchoring section shall not be less than 2 / 3 of its total length. The tie rod (4) fixes the concrete column (1) and the sheet pile (3) through the reserved hole and the anchor cable hole (1-2).

3. The sheet pile-type backing structure under weak disturbance environment as described in claim 2, characterized in that: The anchor hole (1-2) located at the top is 1 / 3 the length of the cantilever section of the concrete column (1) from the top of the concrete column (1). The steel sheet pile (3) is Z-shaped. The tie rod (4) is made of threaded steel. Each tie rod (4) is arranged with two bundles of threaded steel.

4. The sheet pile-type backing structure under weak disturbance environment as described in claim 3, characterized in that: The diameter of the anchor hole (1-2) is 100 mm. A 25×30 mm bearing platform (1-1) is set on the outside of the anchor hole (1-2). The diameter of the reserved hole is 150 mm. The diameter of the corrugated pipe (5) is 50 mm, the inner diameter is 62 mm, and the outer diameter is 82 mm. The tie rod (4) is made of threaded steel with a diameter of 20 mm. Two layers of tie rods (4) are arranged vertically. The inside of the corrugated pipe (5) is also grouted.

5. The sheet pile-type backing structure under weak disturbance environment as described in claim 1, characterized in that: The concrete hardening layer (6) is made of C30 concrete, with a thickness of not less than 300 mm and a width of 1.5 m. An expansion joint (6-1) is set every 5 m. The thickness of the crushed stone mattress layer (2) is 40 cm.

6. The sheet pile-type backing structure under weak disturbance environment as described in claim 1, characterized in that: The retaining plate (9) is prefabricated with a width × height of 0.3 × 0.5 m. The length is determined according to the spacing of the concrete columns (1). The overlap length on the concrete columns (1) is not less than 0.5 m. It is equipped with reinforcing steel bars inside.

7. The sheet pile-type backing structure under weak disturbance environment as described in claim 1, characterized in that: The concrete column (1) is a cuboid with a cross-sectional dimension of 2×3 m. During construction, it is reinforced with internal reinforcing steel bars and cast on site with formwork. The spacing of the concrete columns (1) along the line direction is 5-7 m.

8. The sheet pile type backing structure under weak disturbance environment as described in claim 1, characterized in that: An upper filler (8) is set on the upper part of the waterproof geotextile (7), and the waterproof geotextile (7) completely covers the filler layer (11). When the waterproof geotextile (7) needs to be overlapped, an adhesive material with waterproof effect is used for the overlap, and the overlap width must exceed 10 cm.

9. The construction method of sheet pile type side-width structure in a weakly disturbed environment as described in any one of claims 1-8, comprising the following steps: S1. Preparation work: The preparation work is divided into the prefabrication stage and the on-site treatment stage. The prefabrication stage is carried out in the factory. The steel frame is rolled according to the drawings. The template is coated with release agent to make a mold. After the embedded parts are placed, the concrete is poured. After the concrete hardens, the mold is removed and the retaining plate (9) is prepared. The on-site treatment stage needs to be carried out in conjunction with the design drawings. It includes the leveling of the foundation, the excavation of the foundation of the concrete column (1), the excavation of the existing roadbed, and the construction of the composite foundation. The construction of the composite foundation includes the construction of long and short piles. S2. Install steel sheet piles (3) and pour concrete columns (1): Install steel sheet piles (3) on site according to the design drawings. The overall inclination ratio of the steel sheet piles (3) during construction is 1:

20. The bottom of the steel sheet piles (3) is inserted to the top surface of the existing roadbed gravel cushion layer. The concrete columns (1) are reinforced with steel bars according to the design drawings and concrete is poured. S3. Construction of temporary prestressed anchor rods, crushed stone cushion layer (2) and concrete hardening layer (6): After the above steps are completed, the crushed stone cushion layer (2) in the filling area is constructed. During construction, the existing roadbed crushed stone cushion layer is broken to connect the new roadbed cushion layer with the existing roadbed cushion layer. Concrete is poured on the top of the short pile (10) to form a concrete hardening layer (6). Temporary prestressed anchor rods are installed in the anchor holes (1-2) at the top of the concrete column (1) so that the sheet pile (3) and the concrete column (1) are under tension. S4. Interactive construction of fill layer (11), retaining plate (9), tie rod (4) and corrugated pipe (5): The prefabricated retaining plate (9) is transported to the site, leveled and laid out. The retaining plate (9) is hoisted by a crane with steel cables installed on both sides. After placement, the roadbed fill is poured in layers. The manual leveling is done first, and then the mechanical compaction is carried out. When filling, the retaining plate (9) is at least one layer higher than the filling position, up to the top. When filling and compacting, compaction is carried out from the position of concrete column (1) in sequence. When the filling and compaction reaches the position of the lower anchor hole (1-2), corrugated pipe (5) is installed and the lower tie rod (4) is pre-pulled. Then the upper temporary prestressed anchor is loosened and the filling and compaction work continues until the filling position reaches the position of the upper anchor hole (1-2). When the filling position reaches the position of the upper anchor hole (1-2), corrugated pipe (5) is installed and the upper tie rod (4) is pre-pulled. Construction continues until the filling work is completed. Geogrid is installed after filling to a suitable position. S5. Waterproof geotextile (7) construction: When the filling reaches its designed position, place the waterproof geotextile (7), and then continue to lay and complete the construction.

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