A prefabricated vertical support retaining wall based on recycled concrete and its construction method

Abstract

The present invention relates to the technical field of slope support. The purpose of the present invention is to provide a prefabricated vertical support retaining wall based on recycled concrete and a construction method thereof, comprising a plurality of H-shaped steels and a concrete base; the H-shaped steels are arranged at intervals, and their openings are arranged oppositely, an excavation area is formed between the relative openings of two H-shaped steels, a plurality of prefabricated sandwich columns are inserted in the excavation area, the transverse cross-section of the prefabricated sandwich columns is T-shaped, and comprises a front stopper, a rear stopper and a sandwich part connected between the front stopper and the rear stopper, and a steel cage is also pre-embedded in the prefabricated sandwich column; each front stopper forms a retaining wall, and the steel cages at both ends of the excavation area are welded with lateral force-transmitting steel plates; a plurality of horizontal force-transmitting steel bars are fixed on the steel cage, a fixing groove is provided on the top of the concrete base, and steel slide plates are provided at both ends of the concrete base, the structure has strong integrity, high construction efficiency, has excellent economic benefits, and solves the problem of practical application of recycled concrete.

Description

Technical Field

[0001] The invention relates to the technical field of slope support, and in particular to a prefabricated vertical support retaining wall based on recycled concrete and a construction method thereof. Background Art

[0002] Recycled concrete refers to the new concrete made by crushing, cleaning, grading and mixing abandoned concrete blocks with grading in a certain proportion, partially or completely replacing natural aggregates such as sand and gravel, and then adding water. At present, the use of recycled concrete in construction is generally to adjust the proportion of each component in the recycled concrete and add various high-strength fibers or aggregates to improve the practical applicability of recycled concrete. However, this approach is costly and difficult to promote;

[0003] At present, the School of Civil Engineering of Fuzhou University is carrying out a project on the practical application of recycled concrete. This project provides a practical solution for the application of recycled concrete. The idea of ​​this solution is roughly as follows: the prefabricated parts factory can carry out customized design and manufacture of recycled concrete components according to the requirements of specific projects. By using large-volume recycled concrete and commercial concrete with high local compressive strength, components that meet the design strength of specific projects can be manufactured. After manufacturing, the recycled prefabricated concrete components are directly transported to the construction site for installation and construction, which has excellent construction efficiency.

[0004] The invention patent of Chinese patent application number CN202410447097.4 discloses a prefabricated vertical slope support structure and a construction method thereof, wherein an excavation area is specifically disclosed, wherein concrete support strips in a plurality of prefabricated reinforced concrete components in the excavation area are stacked and spliced ​​up and down to form a support wall, a transverse steel cage is provided inside the concrete support strip, and the transverse steel cage extends out of the front side of the concrete support strip, and a casting template is also provided on the front side of the excavation area, and a cast-in-place concrete area is formed between the casting template and the support wall;

[0005] This prefabricated slope vertical support structure has been found to have some defects in practical application:

[0006] 1. The overall stress condition of the support structure is not ideal;

[0007] 2. A large amount of commercial concrete with a higher grade is required, which is not economical.

[0008] Specifically, the effect of the initial support of the retaining wall depends to a large extent on the thickness of the concrete support strips wrapped around the transverse steel cage. Since the steel cage extends out of the front side of the concrete support strips and waits to be combined with the subsequent cast-in-place concrete, only the concrete support strips and local steel cages are under stress during the construction process, and the mechanical properties are not ideal. At the same time, in order to ensure the support effect and the combination of cast-in-place concrete, a large amount of high-grade commercial concrete is required, which increases the construction cost and the economic benefit is not significant. Summary of the invention

[0009] One of the purposes of the present invention is to provide a prefabricated vertical support retaining wall based on recycled concrete, which utilizes recycled concrete to prefabricate sandwich columns, and cooperates with lateral force-transfer steel plates and horizontal force-transfer steel bars to form an integrally loaded retaining support wall. It has strong structural integrity, high construction efficiency, and excellent economic benefits. It conforms to the concept of sustainable development of construction waste, has good promotion potential, and solves the problem of practical application of recycled concrete.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A prefabricated vertical retaining wall based on recycled concrete, comprising a plurality of H-shaped steels vertically inserted into the soil layer and a concrete base;

[0012] The H-shaped steels are arranged at intervals, and their openings are arranged opposite to each other, and an excavation area is formed between the opposite openings of the two H-shaped steels, and a plurality of transversely spliced ​​prefabricated sandwich columns are vertically inserted in the excavation area;

[0013] The transverse cross section of the prefabricated sandwich column is T-shaped, and includes a front baffle, a rear baffle, and a sandwich portion connected between the front baffle and the rear baffle for supporting the soil body. The transverse length of the front baffle is greater than the transverse lengths of the rear baffle and the sandwich portion. The front baffle and the rear baffle are both precast with high-strength concrete, and the sandwich portion is precast with recycled concrete. A steel cage is also pre-buried in the prefabricated sandwich column.

[0014] The front baffles of adjacent prefabricated sandwich columns are horizontally spliced ​​to form a retaining wall, and the opposite rear baffles and sandwich parts of two adjacent prefabricated sandwich columns form a cast-in-place area between the columns; the steel cages at both ends of the excavation area are respectively welded with lateral force transmission steel plates between the H-shaped steel rear wing plates on the corresponding side, and the lateral force transmission steel plates, the prefabricated sandwich columns and the H-shaped steels are enclosed to form a cast-in-place joint area;

[0015] A plurality of horizontal force-transmitting steel bars spaced apart from each other are also tied and fixed to each of the steel cages, the horizontal force-transmitting steel bars on two adjacent steel cages correspond to each other, and the ends of the adjacent horizontal force-transmitting steel bars on both sides are connected and fixed in the corresponding cast-in-place area between the columns;

[0016] The concrete base is transversely arranged between two adjacent H-shaped steels and is located below a plurality of prefabricated sandwich columns. A fixing groove is provided on the top of the concrete base for inserting the bottom ends of the prefabricated sandwich columns. Both ends of the concrete base are fixed with steel slide plates that fit the belly wall of the H-shaped steel on the corresponding side.

[0017] A second object of the present invention is to provide a construction method for a prefabricated vertical support retaining wall based on recycled concrete.

[0018] The purpose of the present invention is achieved through the following technical solutions:

[0019] Step S1: establishing an initial elevation and a preset elevation, inserting a number of H-shaped steels spaced apart along the extending direction of the slope on the surface of the initial elevation, so that the bottom of each H-shaped steel sinks below the preset elevation, each H-shaped steel is located on the same horizontal axis, and its openings are arranged oppositely, and an excavation area is formed between the opposite openings of two adjacent H-shaped steels, and the front side of the excavation area corresponds to the slope;

[0020] Step S2: digging downwards in the excavation area to form a foundation trench, the depth of which is sufficient to accommodate the concrete foundation, then hoisting the concrete foundation into the foundation trench, and making the steel slide plates at both ends of the concrete foundation fit the webs of the H-shaped steels on both sides;

[0021] Step S3: hoisting a plurality of prefabricated sandwich columns in sequence, so that the retaining wall formed by splicing the front blocking parts of the plurality of prefabricated sandwich columns faces the slope, and ensuring that the bottom of each prefabricated sandwich column is inserted into the fixing groove, and then connecting and fixing the horizontal force transmission steel bars on both sides of the cast-in-place area between each column;

[0022] Step S4: excavating a working area at the rear side of the excavation area, the bottom surface of the working area is lower than the bottom surface of the foundation trench, and then continuing to excavate the soil directly below the concrete foundation on the side of the working area, the concrete foundation slides downward along the H-shaped steel web until the bottom side of the concrete foundation falls to a preset elevation, and a plurality of prefabricated sandwich columns fall into place along with the concrete foundation;

[0023] Step S5: After the prefabricated sandwich column falls into place, the lateral force transmission steel plates on both sides of the excavation area are respectively welded and fixed to the H-shaped steel on the corresponding side, and then a casting template for sealing the cast-in-place area between each column is installed between the lateral force transmission steel plates on both sides;

[0024] Step S6: After the casting formwork is installed, the recycled concrete is cast in the cast-in-place area between the columns and the cast-in-place joint area, and the recycled concrete is vibrated. After the vibration is completed, the recycled concrete is cured. After the curing is completed, the casting formwork is removed to complete the construction.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] 1. The prefabricated sandwich column uses the front baffle, the rear baffle and the sandwich part to wrap the entire steel cage, avoiding local stress on the steel cage, and has good bending and shear resistance. In addition, by locally using commercial concrete with high compressive strength and a large amount of recycled concrete, the overall material cost is effectively reduced, with significant economic benefits. At the same time, it realizes the efficient reuse of construction waste, which is in line with the concept of sustainable development;

[0027] 2. The prefabricated sandwich columns are integrally connected by horizontal force-transmitting steel bars, and the prefabricated sandwich columns can be synergistically stressed, so that the retaining wall can provide the main support force. The rear retaining part and the sandwich part form a structure similar to a reinforcing rib on the rear side of the retaining wall, which further enhances the stability of the structure and achieves excellent anti-deformation ability. At the same time, the lateral force-transmitting steel plate effectively transmits the lateral pressure of the retaining wall to the H-shaped steel, ensuring the uniform force and stability of the support structure.

[0028] 3. By adjusting the thickness ratio of the sandwich part and the back stop in the prefabricated sandwich column, its compressive performance can be optimized according to specific engineering requirements without changing the overall structure of the prefabricated sandwich column, so as to achieve the effect of the same overall specification being flexibly adapted to different design requirements; and only adjusting the thickness ratio of the sandwich part and the back stop will not affect the cast-in-place thickness of the cast-in-place concrete area, further protecting the horizontal force-transmitting steel bars and ensuring the combination effect with the prefabricated sandwich column, thus achieving a dual improvement in structural integrity and mechanical properties, and realizing the long-term durability of the retaining wall;

[0029] 4. The fixing grooves on the concrete base can be used to limit the position of each prefabricated sandwich column, ensuring that the front stop of each prefabricated sandwich column can be accurately spliced ​​to form a retaining wall after hoisting. At the same time, it ensures that the prefabricated sandwich columns can fall in coordination during construction, thereby improving construction efficiency and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of an embodiment of a prefabricated vertical support retaining wall based on recycled concrete of the present invention;

[0031] Figure 2 It is a structural schematic diagram of the prefabricated sandwich column, the lateral force transmission steel plate and the horizontal force transmission steel bar of the present invention;

[0032] Figure 3 yes Figure 2 Schematic diagram of the internal structure;

[0033] Figure 4 is a rear side view of an embodiment of a prefabricated vertical retaining wall based on recycled concrete according to the present invention;

[0034] Figure 5 It is a front side view of an embodiment of a prefabricated vertical retaining wall based on recycled concrete of the present invention;

[0035] Figure 6 is a top view of an embodiment of a prefabricated vertical retaining wall based on recycled concrete according to the present invention;

[0036] Figure 7 It is a structural schematic diagram of the concrete base of the present invention;

[0037] Figure 8 It is a structural schematic diagram of the H-shaped steel of the present invention;

[0038] Fig. 9 This is the construction effect of a prefabricated vertical support retaining wall embodiment based on recycled concrete of the present invention. Figure 1 ;

[0039] Fig.10 This is the construction effect of a prefabricated vertical support retaining wall embodiment based on recycled concrete of the present invention. Figure 2 .

[0040] Explanation of numbers: 1 H-shaped steel, 2 concrete base, 21 fixing groove, 22 steel slide plate, 3 prefabricated sandwich column, 31 front stopper, 32 rear stopper, 33 sandwich part, 34 steel cage, 341 lateral force transmission steel plate, 342 horizontal force transmission steel bar, 4 internal threaded sleeve, 5 blocking block, 100 through hole. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to the accompanying drawings and embodiments:

[0042] like Figure 1-8 FIG. 1 is a schematic diagram of an embodiment of a prefabricated vertical retaining wall based on recycled concrete provided by the present invention:

[0043] A prefabricated vertical retaining wall based on recycled concrete, comprising a plurality of H-shaped steels 1 vertically inserted into a soil layer and a concrete base 2;

[0044] The H-shaped steels 1 are arranged at intervals, and their openings are arranged opposite to each other, and an excavation area is formed between the opposite openings of the two H-shaped steels 1, and a plurality of transversely spliced ​​prefabricated sandwich columns 3 are vertically inserted in the excavation area;

[0045] The transverse cross section of the prefabricated sandwich column 3 is T-shaped, and includes a front stopper 31, a rear stopper 32, and a sandwich portion 33 connected between the front stopper 31 and the rear stopper 32 for supporting the soil. The transverse length of the front stopper 31 is greater than the transverse lengths of the rear stopper 32 and the sandwich portion 33. The front stopper 31 and the rear stopper 32 are both precast with high-strength concrete, and the sandwich portion 33 is precast with recycled concrete. A steel cage 34 is also pre-buried in the prefabricated sandwich column 3.

[0046] Furthermore, the transverse cross-section of the steel cage 34 is also T-shaped, and the thickness of the protective layer from the outer wall surface of the prefabricated sandwich column 3 to the steel cage 34 is not less than 20 mm.

[0047] Among them, the front stopper 31 of each adjacent prefabricated sandwich column 3 is horizontally spliced ​​to form a retaining wall, and the opposite rear stopper 32 and the sandwich part 33 of two adjacent prefabricated sandwich columns 3 form a cast-in-place area between the columns; the steel cages 34 at both ends of the excavation area are respectively welded with lateral force transmission steel plates 341 between the rear wing plates of the H-shaped steel 1 on the corresponding side, and the lateral force transmission steel plates 341, the prefabricated sandwich column 3 and the H-shaped steel 1 are enclosed to form a cast-in-place joint area;

[0048] Furthermore, without changing the overall structure of the prefabricated sandwich column 3, its compressive performance can be optimized according to specific engineering requirements, so as to achieve the effect of the same overall specification being flexibly adapted to different design requirements. Specifically, by adjusting the thickness ratio of the sandwich portion 33 and the rear stop portion 32 in the prefabricated sandwich column 3, the compressive performance of the prefabricated sandwich column 3 can be optimized. For example, the total length of the prefabricated sandwich column 3 in the front-to-back direction is A mm, wherein the thickness of the front stop portion 31 is always A / 3 mm, and the thickness ratio of the sandwich portion 33 to the rear stop portion 32 is 1:1. Then, by increasing the proportion of the sandwich portion 33, the economic benefits can be improved while the strength meets the standard, or by increasing the proportion of the rear stop portion 32, the compressive performance can be improved.

[0049] Furthermore, the thickness of the rear stopper 32 should not be less than 150 mm.

[0050] It should be noted that, for prefabricated sandwich columns 3 of the same specification, adjusting the thickness ratio of the sandwich portion 33 and the rear stop portion 32 will not affect the cast-in-place thickness of the cast-in-place area between the columns.

[0051] The manufacturing process of the prefabricated sandwich column 3 is roughly as follows:

[0052] In the prefabrication factory, the template of the prefabricated sandwich column 3 is placed horizontally, and the steel cage 34 is placed in the template; then a layer of high-strength concrete is poured to form the front stopper 31, so that the front part of the steel cage 34 is completely wrapped, and after the front stopper 31 hardens, the recycled concrete is continuously poured in the template to form the sandwich part 33, and the middle part of the steel cage 34 is wrapped; after the sandwich part 34 hardens, a layer of high-strength concrete is poured thereon to form the rear stopper 32, and the rear part of the steel cage 34 is completely wrapped, and finally the prefabrication of the sandwich column is completed.

[0053] A plurality of horizontal force-transmitting steel bars 342 spaced apart from each other are also tied and fixed to each of the steel cages 34. The horizontal force-transmitting steel bars 342 on two adjacent steel cages 34 correspond to each other one by one, and the ends of the adjacent horizontal force-transmitting steel bars 342 on both sides are connected and fixed in the corresponding cast-in-place area between the columns.

[0054] The concrete base 2 is transversely arranged between two adjacent H-shaped steels 1 and is located below a plurality of prefabricated sandwich columns 3. A fixing groove 21 is provided on the top of the concrete base 2 for inserting the bottom ends of the plurality of prefabricated sandwich columns 3. Steel slide plates 22 are fixedly provided at both ends of the concrete base 2 to fit the belly wall of the H-shaped steel 1 on the corresponding side.

[0055] A plurality of through holes 100 are provided on the web of the H-shaped steel 1, and the plurality of through holes 100 are arranged at intervals in an upper and lower manner. The diameter of the through holes 100 should be larger than the diameter of the aggregate in the recycled concrete. The through holes 100 are provided to facilitate the flow of the recycled concrete poured in the cast-in-place joint areas on both sides of the H-shaped steel 1.

[0056] The ends of the horizontal force-transmitting steel bars 342 are provided with external threads, and a plurality of internal threaded sleeves 4 for connecting the horizontal force-transmitting steel bars 342 on two adjacent steel cages 34 are provided in the cast-in-place area between the columns.

[0057] In some embodiments, each horizontal force-transmitting steel bar 342 is fixed by welding.

[0058] Both ends of the retaining wall extend into the opening of the H-shaped steel 1 on the corresponding side, and blocking blocks 5 are provided between the front sides of both ends of the retaining wall and the front wing plates of the H-shaped steel 1 on the corresponding side.

[0059] The horizontal force-transmitting steel bars 342 at both ends of the excavation area extend to the cast-in-place joint areas on the corresponding two sides respectively.

[0060] The joints between the front stoppers 31 are filled with sealing strips.

[0061] In some embodiments, tooth joints are left on the left and right sides of the sandwich portion 33 of the prefabricated sandwich column 3, the purpose of which is to enable the prefabricated sandwich column 3 to be better connected to the cast-in-place area between the columns to improve the integrity of the structure.

[0062] A construction method for a prefabricated vertical retaining wall based on recycled concrete comprises the following steps:

[0063] Step S1: establishing an initial elevation and a preset elevation, inserting a number of H-shaped steels 1 spaced apart along the extending direction of the slope on the surface of the initial elevation, so that the bottom of each H-shaped steel 1 sinks below the preset elevation, each H-shaped steel 1 is located on the same horizontal axis, and its openings are arranged oppositely, and an excavation area is formed between the opposite openings of two adjacent H-shaped steels 1, and the front side of the excavation area corresponds to the slope;

[0064] Step S2: Dig downward in the excavation area to form a foundation trench, the depth of which is sufficient to accommodate the concrete foundation 2, and then hoist the concrete foundation 2 into the foundation trench (it should be noted that the prefabricated sandwich column 3 is prefabricated in the prefabrication factory in advance, and it already has the corresponding mechanical strength, and can be directly hoisted and constructed after being transported to the site), and make the steel slide plates 22 at both ends of the concrete foundation 2 fit the belly walls of the H-shaped steels 1 on both sides;

[0065] Step S3: sequentially hoisting a plurality of prefabricated sandwich columns 3, so that the retaining wall formed by splicing the front stoppers 31 of the plurality of prefabricated sandwich columns 3 faces the slope, and ensuring that the bottom of each prefabricated sandwich column 3 is inserted into the fixing groove 21, and then connecting and fixing the horizontal force transmission steel bars 342 on both sides of the cast-in-place area between each column;

[0066] Step S4: excavate a working area at the rear side of the excavation area, the bottom surface of the working area is lower than the bottom surface of the foundation trench, and then continue to excavate the soil directly below the concrete foundation 2 on the side of the working area, and the concrete foundation 2 slides downward along the web of the H-shaped steel 1 until the bottom side of the concrete foundation 2 falls to a preset elevation, and a plurality of prefabricated sandwich columns 3 fall into place along with the concrete foundation 2;

[0067] Step S5: Fig. 9 As shown, after the prefabricated sandwich column 3 is dropped into place, the lateral force transmission steel plates 341 on both sides of the excavation area are respectively welded and fixed to the H-shaped steel 1 on the corresponding side, and then the casting templates are installed between the lateral force transmission steel plates 341 on both sides to block the cast-in-place areas between the columns;

[0068] Step S6: Fig.10 As shown, after the casting formwork is installed, the recycled concrete is poured in the cast-in-place area between each column and the cast-in-place joint area, and the recycled concrete is vibrated. After the vibration is completed, the recycled concrete is cured. After the curing is completed, the casting formwork is removed to complete the construction.

[0069] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A prefabricated vertical retaining wall based on recycled concrete, characterized in that: It comprises a plurality of H-shaped steels (1) vertically inserted into the soil layer and a concrete base (2); The H-shaped steels (1) are arranged at intervals, and their openings are arranged opposite to each other, an excavation area is formed between the opposite openings of the two H-shaped steels (1), and a plurality of transversely spliced ​​prefabricated sandwich columns (3) are vertically inserted in the excavation area; The transverse cross-section of the prefabricated sandwich column (3) is T-shaped, and comprises a front baffle (31) for supporting soil, a rear baffle (32), and a sandwich portion (33) connected between the front baffle (31) and the rear baffle (32); the transverse length of the front baffle (31) is greater than the transverse lengths of the rear baffle (32) and the sandwich portion (33); the front baffle (31) and the rear baffle (32) are both formed by precasting high-strength concrete, and the sandwich portion (33) is formed by precasting recycled concrete; a steel cage (34) is also pre-buried in the prefabricated sandwich column (3); The front baffles (31) of adjacent prefabricated sandwich columns (3) are horizontally spliced ​​to form a retaining wall, and the opposite rear baffles (32) and sandwich parts (33) of two adjacent prefabricated sandwich columns (3) form an inter-column cast-in-place area; the steel cages (34) at both ends of the excavation area are respectively welded with lateral force transmission steel plates (341) between the rear wing plates of the H-shaped steel (1) on the corresponding side, and the lateral force transmission steel plates (341), the prefabricated sandwich columns (3) and the H-shaped steel (1) are enclosed to form a cast-in-place joint area; A plurality of horizontal force-transmitting steel bars (342) spaced apart from each other are also tied and fixed to each of the steel cages (34), the horizontal force-transmitting steel bars (342) on two adjacent steel cages (34) correspond to each other one by one, and the ends of the adjacent horizontal force-transmitting steel bars (342) on both sides are connected and fixed in the corresponding cast-in-place area between the columns; The concrete base (2) is transversely arranged between two adjacent H-shaped steels (1) and is located below a plurality of prefabricated sandwich columns (3). A fixing groove (21) is provided at the top of the concrete base (2) for accommodating the bottom ends of the plurality of prefabricated sandwich columns (3) to be inserted. Steel slide plates (22) are fixedly provided at both ends of the concrete base (2) to fit the belly wall of the H-shaped steel (1) on the corresponding side.

2. The prefabricated vertical retaining wall based on recycled concrete according to claim 1 is characterized in that: A plurality of through holes (100) are provided on the web of the H-shaped steel (1), and the plurality of through holes (100) are arranged in an up-and-down manner at intervals.

3. The prefabricated vertical retaining wall based on recycled concrete according to claim 1 is characterized in that: The ends of the horizontal force-transmitting steel bars (342) are provided with external threads, and a plurality of internal threaded sleeves (4) for connecting the horizontal force-transmitting steel bars (342) on two adjacent steel cages (34) are provided in the inter-column cast-in-place area.

4. The prefabricated vertical retaining wall based on recycled concrete according to claim 1 is characterized in that: The two ends of the retaining support wall extend into the opening of the H-shaped steel (1) on the corresponding side, and blocking blocks (5) are provided between the front sides of the two ends of the retaining support wall and the front wing plates of the H-shaped steel (1) on the corresponding side.

5. The prefabricated vertical retaining wall based on recycled concrete according to claim 1 is characterized in that: The horizontal force transmission steel bars (342) at both ends of the excavation area extend to the cast-in-place joint areas on the corresponding two sides.

6. The prefabricated vertical retaining wall based on recycled concrete according to claim 1 is characterized in that: The joints between the front baffles (31) are filled with sealing strips.

7. The construction method of a prefabricated vertical retaining wall based on recycled concrete according to claim 1, characterized in that: The following steps are involved: Step S1: establishing an initial elevation and a preset elevation, inserting a plurality of H-shaped steels (1) spaced apart along the extending direction of the slope on the surface of the initial elevation, so that the bottom of each H-shaped steel (1) sinks below the preset elevation, each H-shaped steel (1) is located on the same horizontal axis, and its openings are arranged opposite to each other, and an excavation area is formed between the opposite openings of two adjacent H-shaped steels (1), and the front side of the excavation area corresponds to the slope; Step S2: digging downwards in the excavation area to form a foundation trench, the depth of which is sufficient to accommodate the concrete foundation (2), then hoisting the concrete foundation (2) into the foundation trench, and making the steel slide plates (22) at both ends of the concrete foundation (2) fit the belly walls of the H-shaped steel (1) on both sides; Step S3: sequentially hoisting a plurality of prefabricated sandwich columns (3) so that the retaining wall formed by splicing the front stoppers (31) of the plurality of prefabricated sandwich columns (3) faces the slope, and ensuring that the bottom of each prefabricated sandwich column (3) is inserted into the fixing groove (21), and then connecting and fixing the horizontal force transmission steel bars (342) on both sides of the cast-in-place area between each column; Step S4: excavating a working area at the rear side of the excavation area, wherein the bottom surface of the working area is lower than the bottom surface of the foundation trench, and then continuing to excavate the soil directly below the concrete base (2) on the side of the working area, wherein the concrete base (2) slides downward along the web of the H-shaped steel (1) until the bottom side of the concrete base (2) falls to a preset elevation, and a plurality of prefabricated sandwich columns (3) fall into place along with the concrete base (2); Step S5: After the prefabricated sandwich column (3) is dropped into place, the lateral force transmission steel plates (341) on both sides of the excavation area are respectively welded and fixed to the H-shaped steel (1) on the corresponding side, and then a casting template for sealing the cast-in-place area between each column is installed between the lateral force transmission steel plates (341) on both sides; Step S6: After the casting formwork is installed, the recycled concrete is cast in the cast-in-place area between the columns and the cast-in-place joint area, and the recycled concrete is vibrated. After the vibration is completed, the recycled concrete is cured. After the curing is completed, the casting formwork is removed to complete the construction.

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