An underground chamber arch-foot beam foundation reinforcement structure and construction method

Abstract

The present invention provides a foundation reinforcement structure and construction method under the arch-foot beam of an underground chamber, including steel pipe piles, a concrete beam structure, connecting steel bars, anchor rods, and anchor plates; the concrete beam structure is arranged at the bottom of the arch foot of the underground chamber, the steel pipe piles extend from the bottom surface of the concrete beam structure into the formation, the anchor rods extend from the side surface of the concrete beam structure into the formation, and the anchor plates are embedded at the bottom inner corners of the concrete beam structure. The present invention can complete foundation reinforcement in a limited and narrow existing space and meet the engineering requirements.

Description

Technical Field

[0001] The present invention belongs to the method for ground reinforcement in a limited and narrow underground chamber, and particularly relates to a ground reinforcement structure and its construction method under the arch foot beam of an underground chamber constructed by the cut-and-cover method in urban rail transit engineering. Background Art

[0002] With the rapid development of urban rail transit, the methods for constructing underground structures have also been gradually developed. The cut-and-cover arch method is widely used in rock formations due to its fast construction speed and few process conversions. However, the cut-and-cover arch method has high requirements for the foundation at the arch foot beam, and the arch foot beam needs to be located on hard bedrock with high bearing capacity. When using strongly weathered rock, moderately weathered rock, etc. with weak bearing capacity as the foundation of the arch foot beam, the cut-and-cover arch method can hardly be constructed. Therefore, in a limited and narrow underground construction space, it is of great significance to study a feasible ground reinforcement structure and construction method for the arch foot beam foundation. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies and defects in the prior art, and provide a ground reinforcement structure and its construction method under the arch foot beam of a cut-and-cover underground chamber, which can complete the ground reinforcement in a limited and narrow existing space and meet the engineering requirements.

[0004] The present invention provides the following technical solutions:

[0005] A ground reinforcement structure under the arch foot beam of an underground chamber, comprising steel pipe piles, a concrete beam structure, connecting steel bars, anchor rods, and anchor plates; the concrete beam structure is arranged at the bottom of the arch foot, the steel pipe piles extend from the bottom surface of the concrete beam structure into the formation, the anchor rods extend from the side surface of the concrete beam structure into the formation, and the anchor plates are embedded at the bottom inner corners of the concrete beam structure.

[0006] Among them, the concrete beam structure is a reinforced concrete beam separately cast on both sides of the underground chamber, which is the structural concrete forming the underground chamber; the top of the concrete beam structure is an inclined surface.

[0007] Among them, the concrete beam structure is provided with an internal steel bar skeleton at least on the bottom surface and side surface of the corner; the steel pipe piles and the anchor rods are respectively welded to the steel bar skeleton; the steel pipe piles and the anchor rods respectively contain grouted concrete.

[0008] Furthermore, the main reinforcement bars of the steel pipe piles and the steel bar skeleton in the concrete beam structure are effectively welded by the side welding of connecting steel bars, and the welding length of the connecting steel bars along the steel pipe piles is not less than 500 mm.

[0009] Among them, the driving angle of the steel pipe piles forms an included angle within 10° with the inclined surface of the concrete beam structure, and there are at least two rows of steel pipe piles, and the row spacing is 0.3 - 0.8 m.

[0010] Among them, the steel pipe pile has a hollow pipe wall. Along the axis in the center of the pipe wall, there are several inner components for fixing and supporting. The inner components include a fixing ring arranged coaxially with the pipe wall and a positioning and supporting member arranged along the outer ring of the fixing ring. In the pipe wall, there are also a secondary grouting pipe and at least one longitudinal steel bar arranged in the direction parallel to the axial direction. The secondary grouting pipe and the longitudinal steel bar are both fixedly arranged on the outer ring of the fixing ring and are spaced by the positioning and supporting member.

[0011] Furthermore, the fixing ring, the positioning and supporting member, the secondary grouting pipe and the longitudinal steel bar are welded and connected to each other; the positioning and supporting member is in the shape of a rectangular frame; several first slurry outlet holes are provided on the pipe wall of the steel pipe pile, which are evenly distributed along the axial direction of the steel pipe pile and are arranged staggeredly along the radial direction; several second slurry outlet holes are provided on the side wall of the secondary grouting pipe, which are evenly distributed along the axial direction of the secondary grouting pipe and are arranged staggeredly along the radial direction; the second slurry outlet holes of the secondary grouting pipe are covered with isolation plastic tapes.

[0012] Among them, the anchor rod adopts a hot-rolled steel welded pipe. The anchor rods are arranged on the side surface of the concrete beam structure in not less than two rows, the row spacing is 0.5 m to 1.0 m, the horizontal interval within the row is 0.5 m to 1.0 m, and the rows are arranged staggeredly.

[0013] Among them, the anchor plate is embedded at the bottom inner corner of the concrete beam structure and is arranged along the whole length of the concrete beam structure. The anchor plate is welded and connected to the steel bar skeleton of the concrete beam structure through the self-owned anchor bars.

[0014] The present invention also provides a construction method for the foundation reinforcement structure under the arch foot beam of the above underground chamber, including the following steps:

[0015] Step 1, determining construction parameters and equipment: According to the structure, size of the underground chamber and the surrounding strata conditions, determine the construction parameters and equipment of the reinforcement structure;

[0016] Step 2, driving anchor rods: Install side wall anchor rods and grout;

[0017] Step 3, driving steel pipe piles: Use steel pipe pile construction equipment to drill holes and install the pipe wall. Install a steel reinforcement cage formed by welding the inner components, the secondary grouting pipe and the longitudinal steel bar in the pipe wall, and then conduct primary grouting and secondary grouting in sequence;

[0018] Step 4, arranging the steel bar skeleton and the anchor plate of the concrete beam structure, and welding and fixing the steel bar skeleton to the steel pipe pile, the anchor rod and the anchor plate respectively;

[0019] Step 5, pouring the concrete beam structure.

[0020] Among them,

[0021] In the said Step 2, the designed grouting pressure is 0.5 to 1.0 MPa. When driving the side wall anchor rods, the primary support structure of the existing chamber shall not be damaged;

[0022] In the third step, it specifically includes: tidying up the construction ground, bringing in the steel pipe pile construction equipment, drilling on-site and installing the pipe wall, installing a steel reinforcement cage formed by welding an inner component, a secondary grouting pipe and longitudinal steel bars inside the pipe wall, and then successively performing primary grouting and secondary grouting; inspecting the quality of the formed steel pipe piles.

[0023] In the fourth step, it specifically includes: setting up the steel reinforcement framework and anchor plates of the concrete beam structure, cleaning the arch foot base, cleaning the arch foot beam base where the concrete beam structure is located, exposing the bedrock, and conducting a base trench inspection; pouring the bottom cushion of the arch foot beam, welding the connecting steel bars to the outside of the steel pipe piles, and binding the steel reinforcement framework; welding the connecting steel bars to the steel reinforcement framework, and fixing the anchor bolts and anchor plates to the steel reinforcement framework.

[0024] In the fifth step, it specifically includes: erecting the formwork of the concrete beam structure, pouring the concrete of the concrete beam structure, and removing the formwork after the concrete of the concrete beam structure reaches 70% of the designed strength.

[0025] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0026] 1. The present invention proposes a method for foundation reinforcement in a limited space by utilizing existing underground chambers. This method does not require the excavation of the chambers to be expanded, does not generate additional projects, and saves cost and construction period.

[0027] 2. By obliquely driving steel pipe piles and anchor bolts, the present invention not only optimizes the structural stress, but also further reduces the requirements of construction machinery for the construction space.

[0028] 3. By connecting the steel pipe piles, anchor bolts and steel reinforcement framework into a whole, the present invention improves the overall stability; the reserved anchor plates provide favorable conditions for subsequent lower part excavation.

[0029] 4. Through the optimized structural design inside the steel pipe piles and secondary grouting, the present invention improves the support strength of the steel pipe piles, and effectively improves the overall support and stability of the reinforcement structure.

[0030] 5. The reinforcement structure of the present invention is simple in composition and can provide sufficient support during the construction of the arch cover at this stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is the cross-sectional view of the foundation reinforcement under the arch foot beam of the underground chamber (station part) of the present invention;

[0032] Figure 2 It is the cross-sectional view of the foundation reinforcement under the arch foot beam of the underground chamber (transition section part) of the present invention;

[0033] Figure 3 It is the cross-sectional view of the foundation reinforcement under the arch foot beam of the underground chamber (running section part) of the present invention;

[0034] Figure 4 It is a partial plan view of the foundation reinforcement under the arch foot beam of the underground chamber according to the present invention;

[0035] Figure 5 This is a partial cross-sectional schematic diagram of the foundation reinforcement under the arch foot beam of the underground chamber according to the present invention;

[0036] Figure 6 It is a schematic diagram of the cross section of the steel pipe pile perpendicular to the axial direction;

[0037] Figure 7 It is a schematic diagram of the cross section of the steel pipe pile parallel to the axial direction;

[0038] Figure 8 This is a schematic diagram of the external structure of the steel pipe pile;

[0039] Figure 9 It is a schematic diagram of the cross section of the secondary grouting pipe perpendicular to the axial direction;

[0040] Figure 10 Schematic diagram of the connection between the anchor plate and the underlying structure. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described below with reference to the accompanying drawings. It is apparent that the embodiments described herein are only a portion of the embodiments of the present invention, and not all of them. All other implementations derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0042] Combine Figure 1-4 As shown, the foundation reinforcement structure beneath the arch foot beam of the underground chamber of the present invention includes steel pipe piles 1, a concrete beam structure 2, connecting steel bars 3, anchor rods 4, and anchor plates 5. Underground chambers suitable for this invention can utilize existing underground chambers with limited space, eliminating the need for additional engineering work and reducing construction costs and time. Existing underground chambers generally have a clear height of no less than 4.5 meters and a clear width of no less than 4 meters.

[0043] A concrete beam structure 2 is installed at the base of the arch foot. It can be a separately cast reinforced concrete beam on either side of the underground chamber. Alternatively, if separate casting is not possible in some areas, the structural concrete of the underground chamber can be used as the concrete beam structure 2. The concrete beam structure 2 is provided with an internal steel reinforcement skeleton 21 on at least the bottom and side surfaces of the corners. The top of the concrete beam structure 2 is sloped, which stabilizes the cast corner structure and saves space.

[0044] The steel pipe pile 1 extends from the bottom surface of the concrete beam structure 2 into the formation. The length is determined according to the geological conditions. Generally, the lower end needs to penetrate into the bedrock (slightly weathered rock) by more than 1.0 m, and the upper end penetrates into the concrete beam structure 2 and is welded to the steel bar framework 21. Specifically, the upper end of the steel pipe pile 1 penetrates into the concrete beam structure 2 by more than 0.3 m, and is effectively welded to the main bars of the steel bar framework 21 in the concrete beam structure 2 through the connecting steel bars 3 by side welding. The welding length of the connecting steel bars 3 along the steel pipe pile 1 is not less than 500 mm, and the diameter of the connecting steel bars 3 can be φ22. In principle, the driving angle of the steel pipe pile 1 is perpendicular to the inclined surface of the concrete beam structure 2. To avoid difficult driving, it can deviate from the perpendicular line of the inclined surface by 5° - 10°. The steel pipe pile 1 and the concrete beam structure 2 are connected into a whole through the connecting steel bars 3 and jointly play a role. To give full play to the combined force of the steel pipe pile 1, the concrete beam structure 2 and the formation, generally there are not less than two rows of steel pipe piles 1, and the row spacing can be selected from 0.3 - 0.8 m.

[0045] The steel pipe pile 1 has a hollow pipe wall 11. Inside the pipe wall 11, several inner components for fixing and supporting are arranged along the axis in the center. The inner components include a fixing ring 12 coaxially arranged with the pipe wall 11 and a positioning and supporting member 13 arranged along the outer circle of the fixing ring 12. Inside the pipe wall 11, a secondary grouting pipe 15 and at least one longitudinal reinforcing bar 14 are also arranged in a direction parallel to the axial direction. The secondary grouting pipe 15 and the longitudinal reinforcing bar 14 are both fixedly arranged on the outer circle of the fixing ring 12 and are spaced apart by the positioning and supporting member 13. The fixing ring 12, the positioning and supporting member 13, the secondary grouting pipe 15, and the longitudinal reinforcing bar 14 can be welded to each other. The positioning and supporting member 13 can be in the shape of a rectangular frame, which can better provide support and reduce the influence on grouting. A number of first slurry outlet holes 16 are provided on the pipe wall 11 of the steel pipe pile 1, which are evenly distributed along the axial direction of the steel pipe pile 1 and are arranged staggeredly in the radial direction for the first non-closed grouting inside the steel pipe pile 1. A number of second slurry outlet holes 17 are provided on the side wall of the secondary grouting pipe 15, which are evenly distributed along the axial direction of the secondary grouting pipe 15 and are arranged staggeredly in the radial direction for the second closed grouting inside the steel pipe pile 1; an isolation plastic tape 18 is also covered on the second slurry outlet holes 17 of the secondary grouting pipe 15 to prevent the slurry from entering the secondary grouting pipe 15 and blocking the second slurry outlet holes 17 during the first grouting, and can normally discharge slurry under the grouting pressure during the second grouting. As a specific embodiment, the pipe wall 11 of the steel pipe pile 1 is made of a seamless steel pipe with a diameter of 159 mm and a wall thickness of 8 mm. The pipe end of the pipe wall 11 is closed, and the pipe body is provided with first slurry outlet holes 16 with a diameter of φ10 mm, which are vertically staggered by 300 mm. To fully ensure the stress effect, three longitudinal reinforcing bars 14 with a diameter of φ18 mm and one secondary grouting pipe 15 with a diameter of φ32 mm are arranged inside the steel pipe pile 1. The pipe end of the secondary grouting pipe 15 is closed, and the pipe body is provided with second slurry outlet holes 17 with a diameter of φ4 mm, which are vertically staggered by 150 mm. The grouting material can adopt ordinary silicate 425 cement, and preferably a certain amount of water reducing agent or micro-expansion agent can also be incorporated. The water-cement ratio of the cement slurry for the first grouting is 0.5:1 to 0.75:1, and the water-cement ratio of the cement slurry for the second grouting is 1:1. The step-by-step grouting method of first non-closed and then closed is beneficial to the full filling of the steel pipe pile 1 with cement and improves the supporting strength of the steel pipe pile 1.

[0046] The anchor rod 4 extends from the side of the concrete beam structure 2 into the formation. Its length is determined according to the geological conditions. Generally, the outer end can penetrate into the formation more than 2 m, and the inner end penetrates into the concrete beam structure 2 and is welded to the steel reinforcement cage 21. As a specific embodiment, the anchor rod 4 is 5 m long, the outer end penetrates into the formation 4.5 m, and the inner end penetrates into the concrete beam structure 2 by 0.5 m. The anchor rod 4 is welded to the concrete beam structure 2 to form an integral whole, and together with the steel pipe pile 1, a stable integral is formed to jointly bear the load transmitted by the upper structure with the formation. The anchor rod 4 is a hollow structure, and grouting cement is also provided inside. Grouting can also be carried out through the grout outlet holes provided on the side wall of the anchor rod 4. Specifically, the anchor rod 4 can be made of φ42 hot-rolled steel welded pipe with a wall thickness of 3.5 mm and Q345B steel; the grouting cement uses ordinary cement slurry, the cement uses #42.5 grade ordinary Portland cement, the water-cement ratio is 1:1, and the designed grouting pressure (final pressure value) is about 0.5 - 1.0 MPa. The anchor rods 4 are generally arranged in no less than two rows along the side of the concrete beam structure 2, the row spacing is 0.5 m - 1.0 m, the horizontal spacing within the row is 0.5 m - 1.0 m, and the rows are staggered in a plum blossom shape.

[0047] The anchor plate 5 is embedded at the bottom inner corner of the concrete beam structure 2 and is arranged along the entire length of the concrete beam structure 2. The anchor plate 5 is welded to the steel reinforcement cage 21 of the concrete beam structure 2 through its own anchor bars and is firmly combined together. The anchor plate 5 is used to be welded to the lower grid 6 or other steel bars during the subsequent construction excavation of the underground chamber, so that the support surface of the lower construction excavation is firmly connected to the concrete beam structure 2, providing favorable conditions for the subsequent construction.

[0048] The construction method of the foundation reinforcement structure under the arch-foot beam of the underground chamber of the present invention is as follows:

[0049] Step 1, determine the construction parameters and equipment: According to the structure, size of the underground chamber and the surrounding formation conditions, determine the relevant parameters such as the size and arrangement method of each part of the reinforcement structure (steel pipe pile 1, concrete beam structure 2, connecting steel bar 3, anchor rod 4, anchor plate 5), and combine the current mature equipment situation to determine the equipment selection. The determination of the parameters such as the size and arrangement method of each part of the reinforcement structure can be carried out by simulating and calculating using many existing conventional engineering design methods. For example, by combining MIDAS computer modeling, the settlement, deformation, stress, etc. during the construction process are controlled and checked to obtain the target parameters. During the construction process, relevant parameters can also be monitored and measured in real time to ensure the accuracy of the model and the engineering safety.

[0050] Step 2, drive the anchor rod 4: Install the side-wall anchor rod 4 and grout. The designed grouting pressure (final pressure value) is about 0.5 - 1.0 MPa. Note that the existing primary support structure of the chamber shall not be damaged when driving the side-wall anchor rod 4.

[0051] Step 3: Driving steel pipe piles 1: Level the construction ground, bring in the construction equipment for steel pipe piles 1, drill holes on-site and install the pipe wall 11, install a steel reinforcement cage formed by welding an inner component, a secondary grouting pipe 15, and longitudinal steel bars 14 inside the pipe wall 11, and then conduct primary grouting and secondary grouting in sequence. Inspect the pile-forming quality of the steel pipe piles 1.

[0052] Step 4: Setting up the steel reinforcement cage 21 and anchor plates 5 of the concrete beam structure 2: Clean the arch foot base, clean the arch foot beam base where the concrete beam structure 2 is located to expose the bedrock, organize all parties to conduct a base trench inspection; pour the cushion layer at the bottom of the arch foot beam, weld the connecting steel bars 3 to the outside of the steel pipe piles 1, and tie the steel reinforcement cage 21; weld the connecting steel bars 3 to the steel reinforcement cage 21, connect the anchor bolts 4 to the steel reinforcement cage 21, and fix the anchor plates 5.

[0053] Step 5: Pouring the concrete beam structure 2: Erect the formwork for the concrete beam structure 2, pour the concrete for the concrete beam structure 2, and remove the formwork after the concrete of the concrete beam structure 2 reaches 70% of the designed strength.

[0054] The protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention shall be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A foundation reinforcement structure under the arch-foot beam of an underground chamber, comprising steel pipe piles (1), a concrete beam structure (2), connecting steel bars (3), anchor rods (4), and anchor plates (5); the concrete beam structure (2) is arranged at the bottom of the arch-foot of the underground chamber, the steel pipe piles (1) extend from the bottom surface of the concrete beam structure (2) into the formation, the anchor rods (4) extend from the side surface of the concrete beam structure (2) into the formation, and the anchor plates (5) are embedded at the bottom inner corner of the concrete beam structure (2); The concrete beam structure (2) is provided with an internal steel bar framework (21) at least on the bottom surface and side surface at the corner; the steel pipe piles (1) and the anchor rods (4) are respectively welded to the steel bar framework (21); the steel pipe piles (1) and the anchor rods (4) respectively have grouted concrete; The main steel bars of the steel pipe piles (1) and the steel bar framework (21) in the concrete beam structure (2) are effectively welded by side welding with the connecting steel bars (3), and the welding length of the connecting steel bars (3) along the steel pipe piles (1) is not less than 500 mm; The steel pipe piles (1) have a hollow pipe wall (11), and a number of internal components for fixing and supporting are arranged along the axis in the center of the pipe wall (11). The internal components include a fixing ring (12) coaxially arranged with the pipe wall (11) and positioning and supporting members (13) arranged along the outer circle of the fixing ring (12). A secondary grouting pipe (15) and at least one longitudinal steel bar (14) are also arranged in the pipe wall (11) in a direction parallel to the axial direction. The secondary grouting pipe (15) and the longitudinal steel bar (14) are both fixedly arranged on the outer circle of the fixing ring (12) and spaced by the positioning and supporting members (13); The fixing ring (12), the positioning and supporting members (13), the secondary grouting pipe (15), and the longitudinal steel bar (14) are welded to each other; the positioning and supporting members (13) are in the shape of a rectangular frame; a number of first slurry outlet holes (16) are provided on the pipe wall (11) of the steel pipe piles (1), which are evenly distributed along the axial direction of the steel pipe piles (1) and staggered along the radial direction; a number of second slurry outlet holes (17) are provided on the side wall of the secondary grouting pipe (15), which are evenly distributed along the axial direction of the secondary grouting pipe (15) and staggered along the radial direction; the second slurry outlet holes (17) of the secondary grouting pipe (15) are covered with isolation plastic tapes (18); The anchor plates (5) are embedded at the bottom inner corners of the concrete beam structure (2), are arranged along the whole length of the concrete beam structure (2), and are welded to the steel bar framework (21) of the concrete beam structure (2) through the self-provided anchor bars. During the subsequent construction and excavation of the underground chamber, the anchor plates (5) are welded to the lower grids (6) or other steel bars.

2. The foundation reinforcement structure under the arch springing beam of the underground chamber according to claim 1, characterized in that The concrete beam structure (2) is a reinforced concrete beam separately cast on both sides of the underground chamber and is the structural concrete forming the underground chamber; the top of the concrete beam structure (2) is an inclined surface.

3. The foundation reinforcement structure under the arch springing beam of the underground chamber according to claim 1, characterized in that The driving angle of the steel pipe piles (1) forms an included angle of within 10° with the inclined surface of the concrete beam structure (2), and there are not less than two rows of steel pipe piles (1), and the row spacing is 0.3 - 0.8 m.

4. The foundation reinforcement structure under the arch springing beam of the underground chamber according to claim 1, characterized in that, The anchor rod (4) is made of hot-rolled steel welded pipe. There are at least two rows of the anchor rods (4) along the side surface of the concrete beam structure (2), the row spacing is 0.5 m to 1.0 m, the horizontal interval within the row is 0.5 m to 1.0 m, and the rows are arranged staggeredly.

5. The construction method of the foundation reinforcement structure under the arch-foot beam of the underground chamber according to any one of claims 1-4, comprising the following steps: Step 1, determining construction parameters and equipment: determining the construction parameters and equipment of the reinforcement structure according to the structure, size of the underground chamber and the surrounding strata conditions. Step 2, driving the anchor rods (4): installing the side-wall anchor rods (4) and grouting. Step 3, driving the steel pipe piles (1): using the construction equipment of the steel pipe piles (1) to drill holes and install the pipe wall (11), installing a steel reinforcement cage formed by mutually welding an inner component, a secondary grouting pipe (15) and longitudinal steel bars (14) in the pipe wall (11), and then conducting primary grouting and secondary grouting in sequence. Step 4, setting the steel reinforcement cage (21) and the anchor plate (5) of the concrete beam structure (2), and welding and fixing the steel reinforcement cage (21) to the steel pipe piles (1), the anchor rods (4) and the anchor plate (5) respectively. Step 5, pouring the concrete beam structure (2).

6. According to the construction method described in claim 5, it is characterized in that in the said Step 2, the designed grouting pressure is 0.5 to 1.0 MPa, and the initial support structure of the existing chamber shall not be damaged when driving the side-wall anchor rod 4. in the said Step 3, it specifically includes: tidying the construction ground, the construction equipment of the steel pipe piles (1) entering the site, drilling holes on site and installing the pipe wall (11), installing a steel reinforcement cage formed by mutually welding an inner component, a secondary grouting pipe (15) and longitudinal steel bars (14) in the pipe wall (11), and then conducting primary grouting and secondary grouting in sequence; inspecting the pile-forming quality of the steel pipe piles (1). in the said Step 4, it specifically includes: setting the steel reinforcement cage (21) and the anchor plate (5) of the concrete beam structure (2), cleaning the arch-foot base, cleaning the arch-foot beam base where the concrete beam structure (2) is located, exposing the bedrock, and conducting the base trench inspection; pouring the bottom cushion of the arch-foot beam, welding the connecting steel bars (3) to the outside of the steel pipe piles (1), binding the steel reinforcement cage (21); welding the connecting steel bars (3) to the steel reinforcement cage (21), welding the anchor rods (4) to the steel reinforcement cage (21), and fixing the anchor plate (5). in the said Step 5, it specifically includes: erecting the formwork of the concrete beam structure (2), pouring the concrete of the concrete beam structure (2), and removing the formwork after the concrete of the concrete beam structure (2) reaches 70% of the designed strength.

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