Composite supporting system for excavation of soft soil texture foundation pit

Abstract

The utility model discloses a composite support system for excavation of a soft soil texture foundation pit, which comprises SMW (soil mixing wall) construction method piles, three-shaft mixing piles and an underground support structure, and the SMW construction method piles are arranged at intervals along the outer side of the foundation pit in the circumferential direction to form an outer enclosure structure. The three-shaft mixing piles are arranged along the inner side of the foundation pit at intervals and located on one side of the SMW construction method piles so as to form an inner reinforcing structure, the underground supporting structure is arranged in the SMW construction method piles and located in the foundation pit, and the underground supporting structure comprises an underground body, horizontal inner supports, stand column piles, latticed columns and adjustable inclined throwing supports. The latticed columns are vertically arranged below the horizontal inner supports, the bottom ends of the latticed columns are inserted into the stand column piles, and the adjustable inclined throwing supports are installed between the side walls of the underground body and a bottom plate of the underground body in an inclined mode. A composite supporting system composed of the composite supporting structure and the underground supporting structure is adopted, and the composite supporting system is suitable for soft soil geologic condition supporting and can provide higher supporting force.

Description

Technical Field

[0001] This utility model relates to the field of soft soil foundation pit construction technology, specifically to a composite support system for soft soil foundation pit excavation. Background Technology

[0002] During the excavation of foundation pits, various problems can easily occur, such as soil slippage, pit instability, pile displacement, pit bottom heave, severe water leakage in the retaining structure, soil erosion, and even damage. These problems pose a significant threat to the safety of surrounding buildings, underground structures, and pipelines. Therefore, it is necessary to construct foundation pit support structures to protect the stability of the foundation pit and its surrounding objects during the construction phase. Existing foundation pit support structures generally adopt an internal bracing method, primarily using a combination of bored piles and concrete internal bracing. The bored piles are arranged vertically along the perimeter of the foundation pit, and a capping beam is poured at the top of each pile. The bored piles are connected to the concrete internal bracing through the capping beam, which restricts soil deformation.

[0003] Existing foundation pit support structures have the following shortcomings during foundation pit excavation and construction:

[0004] 1) Vertically arranging bored piles around the foundation pit as support piles for the foundation pit, using only one type of pile for foundation pit support, the reinforcement effect of the foundation pit is not strong enough, the support bearing capacity is low, and the foundation pit is prone to deformation.

[0005] 2) Traditional single-pillar support and concrete internal bracing are not suitable for the rheological properties of soft soil silt, resulting in a significant lateral soil squeezing effect. This leads to the support structure bearing asymmetrical loads, making it unsuitable for foundation pit support in soft soil geology and weak sandy strata. Utility Model Content

[0006] The technical problem this utility model aims to solve is to address the deficiencies of existing technologies by providing a composite support system design consisting of a composite support structure and an underground support structure. This system is suitable for more complex soft soil geological conditions and deeper foundation pit support, providing stronger support force and better stability, ensuring the safety and bearing capacity of the entire foundation pit support, and featuring adjustable inclined bracing that allows for length adjustment, providing adjustable support strength for the underground structure, improving the support effect and flexibility of the adjustable inclined bracing, and making it a practical composite support system.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A composite support system for soft soil foundation pit excavation includes SMW (Surface Movable Mixing) piles, triaxial mixing piles, and an underground support structure. The SMW piles are arranged circumferentially along the outer side of the foundation pit to form an outer retaining structure. The triaxial mixing piles are arranged circumferentially along the inner side of the foundation pit and located on one side of the SMW piles to form an inner reinforcement structure. The underground support structure is located inside the SMW piles and within the foundation pit. The underground support structure includes an underground main body, horizontal internal supports, column piles, lattice columns, and adjustable inclined braces. The horizontal internal supports are located above the underground main body. The column piles are vertically arranged on one side of the underground main body to form structural columns of the underground main body. The lattice columns are vertically arranged below the horizontal internal supports and connected to the horizontal internal supports. The bottom end of the lattice columns is inserted into the column piles. The adjustable inclined braces are installed at an angle between the side wall and the bottom slab of the underground main body. A concrete slab brace is fixed to one side of the side wall of the underground main body.

[0009] Furthermore, the adjustable inclined brace includes a brace transition end, a brace truss section, a brace adjustment end, and an adjuster. The brace transition end is located at the upper end of the brace truss section and is detachably installed with the brace truss section. The brace adjustment end is located at the lower end of the brace truss section and is detachably installed with the brace truss section. The adjuster is threadedly connected to the brace adjustment end. A first support is installed on the upper part of the side wall of the underground main body, and a second support is installed on the bottom plate of the underground main body. The adjustable inclined brace is detachably connected to the first support of the side wall through the brace transition end, and the adjustable inclined brace is detachably connected to the second support of the bottom plate through the adjuster.

[0010] Furthermore, the outrigger adjustment end includes a first flange plate, a first connector, and a first adjustment sleeve. The first flange plate is detachably installed at the lower end of the outrigger truss section via the first connector. One end of the first adjustment sleeve is fixed to the first flange plate. The adjuster includes an adjustment screw, a second adjustment sleeve, a first connecting plate, and a first connecting ear plate. One side of the first connecting plate is connected to one end of the first connecting ear plate. One end of the second adjustment sleeve is fixed to the other side of the first connecting plate. The other end of the second adjustment sleeve is threadedly connected to one end of the adjustment screw. The other end of the adjustment screw is threadedly connected to the other end of the first adjustment sleeve of the outrigger adjustment end to achieve a threaded connection between the adjuster and the outrigger adjustment end. The adjuster is detachably connected to the second support of the base plate via the first connecting ear plate.

[0011] Furthermore, the outrigger transition end includes a second flange plate, a second connector, and a second connecting ear plate. The second flange plate is detachably installed on the upper end of the outrigger truss section via the second connector. One end of the second connecting ear plate is fixed to the second flange plate, and the other end of the second connecting ear plate is detachably connected to the first support of the side wall.

[0012] Furthermore, the outrigger truss section includes two sets of outrigger truss modules and fixing bolts. Each set of outrigger truss modules has a third flange plate fixed at both ends. Adjacent sets of outrigger truss modules are connected to each other by fixing bolts and the third flange plate to form an outrigger truss section.

[0013] Furthermore, the underground support structure includes a replacement concrete slab and pre-embedded reinforcing bars. The two ends of the replacement concrete slab are fixed between the upper part of the side wall of the underground main structure and the SMW method piles by pre-embedded reinforcing bars.

[0014] Furthermore, an H-beam is inserted into the upper part of the SMW method pile.

[0015] Furthermore, a cap beam is fixed to the top of the SMW method pile.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1) The composite support system of this utility model includes SMW method piles, triaxial mixing piles, and underground support structure. The SMW method piles are arranged at intervals along the outer periphery of the foundation pit to form an outer protective structure. The triaxial mixing piles are arranged at intervals along the inner side of the foundation pit and located on one side of the SMW method piles to form an inner reinforcement structure. The underground support structure is set inside the SMW method piles and located inside the foundation pit. The underground support structure includes an underground main body, horizontal inner support, column piles, lattice columns, and adjustable inclined bracing. The column piles are vertically set on one side of the underground main body to form the structural columns of the underground main body. The lattice columns are vertically arranged below the horizontal inner support and connected to the horizontal inner support. The bottom end of the lattice columns is inserted into the column piles. The adjustable inclined bracing is installed at an inclination between the side wall of the underground main body and the bottom plate of the underground main body. This utility model adopts a composite support system design consisting of a composite support structure and an underground support structure. It is suitable for more complex soft soil geological conditions and deeper foundation pit support, and can provide stronger support force and better stability, ensuring the safety and bearing capacity of the entire foundation pit support. The adjustable inclined bracing can be length-adjusted to provide adjustable support strength for the underground main body, improving the support effect, flexibility and practicality of the adjustable inclined bracing.

[0018] 2) The underground support structure of this utility model includes a replacement concrete slab and pre-embedded steel bars. The two ends of the replacement concrete slab are fixed to the upper part of the side wall of the underground main structure and the SMW method piles through the pre-embedded steel bars. The replacement concrete slab is used as a new support structure to bear the load originally borne by the internal support, realize the smooth transfer of support force, and ensure that the stability of the foundation pit is not affected when the internal support is removed. Attached Figure Description

[0019] Figure 1 This utility model describes the overall plan of the foundation pit support using a composite support system.

[0020] Figure 2 This is a plan view of the SMW method piles of this utility model arranged at intervals along the circumference of the outer side of the foundation pit;

[0021] Figure 3 This is a plan view of the three-axis mixing piles of this utility model arranged at intervals along the inner side of the foundation pit;

[0022] Figure 4 This is a utility model Figure 1 Section 1-1;

[0023] Figure 5 This is a detailed drawing of the replacement support concrete slab of this utility model;

[0024] Figure 6 This is a schematic diagram showing the relationship between the adjustable inclined brace of this utility model and the base plate and side wall;

[0025] Figure 7 This is a schematic diagram of the adjustable inclined brace of this utility model;

[0026] Figure 8 This is a schematic diagram of the structure of the transition end of the adjustable inclined brace in this utility model;

[0027] Figure 9 This is a schematic diagram of the adjustable end of the adjustable inclined brace in this utility model;

[0028] Figure 10 This is a utility model Figure 9 Cross-sectional view of AA in the middle;

[0029] Figure 11 This is a schematic diagram of the adjuster in the adjustable inclined boom of this utility model;

[0030] Figure 12 This is a structural schematic diagram of a single set of outrigger truss modules in the adjustable inclined outrigger of this utility model;

[0031] Figure 13 This is a schematic diagram showing the relationship between the side wall and the aluminum frame wooden formwork of this utility model;

[0032] Figure 14 This is a structural schematic diagram of the aluminum frame wood formwork of this utility model.

[0033] In the diagram: SMW method pile 1, capping beam 11, H-beam 12, triaxial mixing pile 2, underground support structure 3, underground main body 31, side wall 311, first support 312, first embedded panel 313, first embedded anchor plate 314, bottom plate 315, second support 316, second embedded panel 317, second embedded anchor plate 318, horizontal internal support 32, column pile 33, lattice column 34, adjustable inclined brace 35, brace transition end 351, second flange plate 3511, second connecting ear plate 3512, brace truss section 352, brace truss module 3521, upper chord 35211, lower chord 35212, web member 35213, third flange plate 3522, outrigger adjustment end 353, first flange plate 3531, first adjusting sleeve 3532, first reinforcing plate 3533, adjuster 354, adjusting screw 3541, second adjusting sleeve 3542, first connecting plate 3543, first connecting ear plate 3544, second reinforcing plate 3545, replacement support concrete slab 36, embedded steel bar 361, concrete slab support 37, aluminum frame wood formwork 38, aluminum alloy frame 381, film-coated plywood 382, ​​intercepting ditch 4, drainage ditch 5. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings, which form part of this specification. The principles of the present invention will be illustrated through embodiments, and other aspects, features, and advantages of the present invention will become apparent from this detailed description. In the accompanying drawings, the same or similar parts in different figures are indicated by the same reference numerals.

[0035] Example 1

[0036] like Figures 1-2As shown, this utility model provides a composite support system for soft soil foundation pit excavation. The composite support system includes SMW method piles 1, triaxial mixing piles 2, and an underground support structure 3. The SMW method piles 1 are arranged at intervals along the outer periphery of the foundation pit to form an outer retaining structure. The triaxial mixing piles 2 are arranged at intervals along the inner side of the foundation pit and located on one side of the SMW method piles 1 to form an inner reinforcement structure. The underground support structure is set inside the SMW method piles 1 and located inside the foundation pit. In specific implementation, the outer retaining structure of this utility model is constructed using a triaxial cement mixing pile machine in a clockwise direction along the periphery of the foundation pit. The pile diameter of the SMW method piles 1 is 850mm@1200mm, and the pile body of the SMW method piles 1 penetrates ≥2m into the strongly weathered silty mudstone layer, playing the role of foundation pit support and anti-overturning. The clockwise rotation is more conducive to the mixing of the triaxial mixing pile machine 2. The mixing head is inserted and the soil is mixed. Adjacent SMW method piles 1 interlock with each other. The internal reinforcement structure is constructed by using 850mm@1800mm diameter triaxial mixing piles 2 in a counterclockwise direction along the inner side of the foundation pit. The length of the triaxial mixing piles 2 extends to 5m below the bottom of the foundation pit. The pile body penetrates the silt layer and enters the underlying hard soil layer ≥1m. The triaxial mixing piles 2 adopt a counterclockwise rotation direction and form a reverse shear with the clockwise direction of the inner side of the foundation pit to improve the shear strength of the soil, thereby forming a structure with sufficient strength and stability. By combining the clockwise rotation direction of the outer piles and the counterclockwise rotation direction of the inner piles, and with different pile diameter parameters (850@1200 and 850@1800), a composite reinforcement zone is formed. In specific implementation, a water interception ditch 4 is set on the outside of the SMW method piles 1, and a drainage ditch 5 is set at the bottom of the foundation pit and on the inner side of the SMW method piles 1. The underground support structure 3 includes an underground main body 31, a horizontal inner support 32, column piles 33, a lattice column 34, and an adjustable inclined brace 35. The horizontal inner support 32 is located above the underground main body 31. The column piles 33 are vertically set on one side of the underground main body 31 to form the structural column of the underground main body 31. The lattice column 34 is vertically arranged below the horizontal inner support 32 and connected to the horizontal inner support 32. The bottom end of the lattice column 34 is inserted into the column pile 33. The adjustable inclined brace 35 is installed at an angle between the side wall 311 of the underground main body 31 and the bottom plate 315 of the underground main body 31. A concrete slab support 37 is fixed on one side of the side wall 311 of the underground main body 31. In specific implementation, the fixed concrete slab support 37 is a 300mm thick C30 plain concrete slab support 37.This invention utilizes SMW (Self-Mixed Mixing) piles 1 to form an outer retaining structure arranged at intervals on the outside of the foundation pit, and interspersed triaxial mixing piles 2 at intervals around the inner perimeter of the foundation pit. The triaxial mixing piles 2 and SMW piles 1 together form a composite support structure for the foundation pit, reinforcing the soil within the pit and providing support and anti-overturning functions. This improves the shear and compressive strength of the soil, reduces the deformation of the foundation pit, and inserts lattice columns 34 into the upper end of the column piles 33 to provide vertical bearing capacity for the horizontal inner supports 32. The horizontal inner supports 32, through the corresponding lattice columns 34, support the inner supports of the foundation pit. The structure uses concrete slab supports 37 as the foundation support for the pit, and the basement sidewalls as the main load-bearing structure to form a solid and stable underground main body 31. Through the coordinated bearing of multiple supports, the load-bearing capacity and stability of the underground main body 31 are ensured. Adjustable inclined bracing 35 is also installed between the sidewalls 311 and the bottom slab 315 of the underground main body 31. The adjustable inclined bracing 35, together with the underground main body 31, SMW method piles 1, and horizontal internal supports 32, are used as foundation pit support to improve the compressive strength of the foundation pit and make it more suitable for the support construction of foundation pits in soft soil.

[0037] In specific implementation, the underground support structure 3 of this utility model also includes a replacement concrete slab 36 and pre-embedded steel bars 361. The two ends of the replacement concrete slab 36 are fixed between the upper part of the side wall 311 of the underground main body 31 and the SMW method pile 1 through the pre-embedded steel bars 361. The replacement concrete slab 36 is 600mm thick. Using the replacement concrete slab 36 as a new support structure can bear the load originally borne by the internal support, realize the smooth transfer of support force, and ensure that the stability of the foundation pit is not affected when the internal support is removed.

[0038] In this embodiment, an H-beam 12 is inserted into the upper part of the SMW method pile 1, forming a water-resistant curtain at the lower part of the SMW method pile 1. The inserted H-beam 12 serves to support the foundation pit and prevent overturning, ensuring the safety of the foundation pit support. Moreover, the inserted H-beam 12 is a common type of steel, which is convenient to obtain and construct, saving project costs. The water-resistant curtain formed at the lower part of the SMW method pile 1 prevents water from seeping into the foundation pit from the soil on the side wall, ensuring the seepage safety of the entire foundation pit.

[0039] In specific implementation, this utility model has a cap beam 11 fixed at the top of the SMW method pile 1.

[0040] In this embodiment, the adjustable inclined brace 35 includes a brace transition end 351, a brace truss section 352, a brace adjustment end 353, and an adjuster 354. The brace transition end 351 is located at the upper end of the brace truss section 352 and is detachably installed with the brace truss section 352. The brace adjustment end 353 is located at the lower end of the brace truss section 352 and is detachably installed with the brace truss section 352. The adjuster 354 is threadedly connected to the brace adjustment end 353. A first support 312 is installed on the upper part of the side wall 311 of the underground main body 31, and a second support 316 is installed on the bottom plate 315 of the underground main body 31. The adjustable inclined brace 35 is detachably connected to the first support 312 of the side wall 311 through the brace transition end 351, and the adjustable inclined brace 35 is detachably connected to the second support 316 of the bottom plate 315 through the adjuster 354. The adjustable inclined brace 35 is assembled from a brace transition end 351, a brace truss section 352, a brace adjustment end 353, and an adjuster 354. It adopts a modular design, facilitating transportation and rapid installation. The adjustable inclined brace 35 can be recycled after dismantling, saving costs and reducing project expenses. Specifically, the first support 312 is installed on the side wall 311 through a first embedded panel 313 and a first embedded anchor plate 314, and the second support 316 is installed on the base plate 315 through a second embedded panel 317 and a second embedded anchor plate 318.

[0041] The adjustable end 353 of this utility model includes a first flange plate 3531, a first connector, and a first adjusting sleeve 3532. The first flange plate 3531 is detachably installed at the lower end of the adjustable truss section 352 via the first connector. One end of the first adjusting sleeve 3532 is fixed to the first flange plate 3531. The adjuster 354 includes an adjusting screw 3541, a second adjusting sleeve 3542, a first connecting plate 3543, and a first connecting ear plate 3544. One side of the first connecting plate 3543 is connected to the first connecting ear plate 3544. One end of 544 is connected to the first connecting plate 3543. One end of the second adjusting sleeve 3542 is fixed to the other side of the first connecting plate 3543. The other end of the second adjusting sleeve 3542 is threadedly connected to one end of the adjusting screw 3541. The other end of the adjusting screw 3541 is threadedly connected to the other end of the first adjusting sleeve 3532 of the throwing support adjusting end 353 to realize the threaded connection between the adjuster 354 and the throwing support adjusting end 353. The adjuster 354 is detachably connected to the second support 316 of the base plate 315 through the first connecting ear plate 3544. In specific implementation, the first and second connecting parts can be bolts. A first internal thread is provided inside the first adjusting sleeve 3532, and a second internal thread is provided inside the second adjusting sleeve 3542, so that the adjusting screw 3541 can be threadedly connected to the first and second adjusting sleeves 3532. A first reinforcing plate 3533 is provided at the fixing point between the first adjusting sleeve 3532 and the first flange plate 3531. The first reinforcing plate 3533 is distributed along the outer periphery of the first adjusting sleeve 3532 to reinforce the connection of the first adjusting sleeve 3532. A second reinforcing plate 3545 is provided at the fixing point of the sleeve 3542 and the first connecting ear plate 3544. The second reinforcing plate 3545 is distributed along the outer periphery of the second adjusting sleeve 3542 to reinforce the connection of the second adjusting sleeve 3542. The outrigger adjustment end 353 cooperates with the adjusting screw 3541 of the adjuster 354 and the second adjusting sleeve 3542 through the first adjusting sleeve 3532, thereby realizing the length adjustment of the adjustable inclined outrigger 35. It can be adjusted according to the support angle requirements of the base plate 315 of the underground main body 31 and the side wall 311. The adjustment is convenient and the support stability is good.

[0042] The outrigger transition end 351 of this utility model includes a second flange plate 3511, a second connector, and a second connecting ear plate 3512. The second flange plate 3511 is detachably installed on the upper end of the outrigger truss section 352 via the second connector. One end of the second connecting ear plate 3512 is fixed to the second flange plate 3511, and the other end of the second connecting ear plate 3512 is detachably connected to the first support 312 of the side wall 311. In a specific implementation of this embodiment, a first connecting bolt is provided at the connection between the second connecting ear plate 3512 and the first support 312, thereby achieving a detachable connection between the second connecting ear plate 3512 and the first support 312. A second connecting bolt is provided at the connection between the first connecting ear plate 3544 and the second support 316, thereby achieving a detachable connection between the first connecting ear plate 3544 and the second support 316.

[0043] The outrigger truss section 352 of this utility model includes two sets of outrigger truss modules 3521 and fixing bolts. Each set of outrigger truss modules 3521 has a third flange plate 3522 fixed at both ends. Adjacent sets of outrigger truss modules 3521 are connected to each other by fixing bolts and the third flange plate 3522 to form the outrigger truss section 352. In this embodiment, each set of outrigger truss modules 3521 includes an upper chord 35211, a lower chord 35212, and a web member 35213. The upper chord 35211 and lower chord 35212 are arranged parallel to each other, and their ends are fixed by the third flange plate 3522. The web member 35213 is installed between the upper chord 35211 and lower chord 35212. The installed web member 35213 includes two structures: a straight web member 35213 and a diagonal web member 35213.

[0044] In a specific implementation of this utility model embodiment, several aluminum frame wood templates 38 can be fixed on the side walls 311 around the underground main body 31. The aluminum frame wood templates 38 are made of prefabricated aluminum alloy profiles. The aluminum alloy profiles are cut and welded to form an aluminum alloy frame 381. The film-coated wood plywood 382 is cut and fixed to the bottom of the aluminum alloy frame 381 to form the aluminum frame wood template 38. The aluminum frame wood template 38 is made of film-coated wood plywood 382 and aluminum alloy frame 381. The aluminum frame wood template 38 can be laid flat on the side walls 311 to ensure the construction accuracy of the side walls 311. The film-coated wood plywood 382 on each aluminum frame wood template 38 is made of 18mm thick plastic-coated plywood nailed on.

[0045] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of this application. All equivalent changes and modifications made in accordance with the scope of this application should still fall within the scope of the present invention.

Claims

1. A composite support system for excavation of a foundation pit in soft ground, characterised in that: The composite support system comprises SMW method piles, triaxial mixing piles and an underground support structure, the SMW method piles are arranged along the outer side of the foundation pit in a circumferential interval to form an outer enclosure structure, the triaxial mixing piles are arranged along the inner side of the foundation pit in an interval and located on one side of the SMW method piles to form an inner reinforcement structure, and the underground support structure is arranged in the SMW method piles and located inside the foundation pit.

2. The composite bracing system for excavation of soft ground geotechnical basements according to claim 1, characterized in that: The adjustable inclined throw support comprises a throw support transition end, a throw support truss section, a throw support adjusting end and an adjuster, the throw support transition end is located at the upper end of the throw support truss section and detachably installed with the throw support truss section, the throw support adjusting end is located at the lower end of the throw support truss section and detachably installed with the throw support truss section, the adjuster is threadedly connected with the throw support adjusting end, a first support is installed on the upper part of the side wall of the underground main body, a second support is installed on the bottom plate of the underground main body, the adjustable inclined throw support is detachably connected with the first support of the side wall through the throw support transition end, and the adjustable inclined throw support is detachably connected with the second support of the bottom plate through the adjuster.

3. The composite bracing system for excavation of soft ground geotechnical basements according to claim 2, characterized in that: The throw support adjusting end comprises a first flange plate, a first connecting piece and a first adjusting sleeve, the first flange plate is detachably installed at the lower end of the throw support truss section through the first connecting piece, one end of the first adjusting sleeve is fixed on the first flange plate, the adjuster comprises an adjusting screw, a second adjusting sleeve, a first connecting plate and a first connecting lug plate, one side of the first connecting plate is connected with one end of the first connecting lug plate, one end of the second adjusting sleeve is fixed on the other side of the first connecting plate, the other end of the second adjusting sleeve is threadedly connected with one end of the adjusting screw, the other end of the adjusting screw is threadedly connected with the other end of the first adjusting sleeve of the throw support adjusting end to realize the threadedly connection of the adjuster with the throw support adjusting end, and the adjuster is detachably connected with the second support of the bottom plate through the first connecting lug plate.

4. The composite bracing system for excavation in soft ground conditions according to claim 2, characterized in that: The throw support transition end comprises a second flange plate, a second connecting piece and a second connecting lug plate, the second flange plate is detachably installed at the upper end of the throw support truss section through the second connecting piece, one end of the second connecting lug plate is fixed on the second flange plate, and the other end of the second connecting lug plate is detachably connected with the first support of the side wall.

5. The composite bracing system for excavation in soft ground conditions according to claim 2, characterized in that: The throw support truss section comprises two groups of throw support truss modules and fixing bolts, the two ends of each group of throw support truss modules are fixed with third flange plates, and the adjacent two groups of throw support truss modules are connected in a matched mode through the fixing bolts and the third flange plates to form the throw support truss section.

6. The composite bracing system for excavation in soft ground conditions according to claim 1, characterized in that: The underground support structure comprises support concrete plates and embedded steel bars, and two ends of the support concrete plates are fixed between the upper part of the side wall of the underground main body and the SMW method pile through the embedded steel bars.

7. The composite bracing system for excavation of soft ground geotechnical basements according to claim 1, characterized in that: A H-shaped steel is inserted into the upper part of the SMW method pile.

8. The composite bracing system for excavation of soft ground geotechnical basements according to claim 1, characterized in that: A crown beam is fixed to the top end of the SMW method pile.

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