Pit-in-pit narrow fertile groove flow state solidified soil backfilling system and construction method

Abstract

To provide a pit-in-pit narrow fertile groove flow state solidified soil backfilling system and construction method.SOLUTION: A pit-in-pit narrow fertile groove flow state solidified soil backfilling system comprises a pit-in-pit excavation enclosure system, a fertile groove floor reserved post-cast strip system, a fertile groove foundation reinforcing system, a fertile groove pipeline anti-deformation supporting system and a basement waterproof system. A technology of reserving the post-cast strip through the fertile groove floor slab is adopted, and the temporary steel plate support is arranged on the post-cast strip to serve as a temporary support of a formwork system, so that synchronous construction of structural slabs of the same floor in different subareas of a foundation pit is guaranteed; meanwhile, a second fertile groove is backfilled with flow-state solidified soil, then a second floor waterproof system is constructed, and finally a sealing post-cast strip is constructed, so that the construction efficiency and quality of the basement main body structure are improved; a fertile groove foundation reinforcement technology is adopted, the steel pipe piles are arranged in the fertile grooves in a driving mode, and the flow state solidified soil is backfilled, so that the backfilling compactness of the foundation pit fertile grooves is improved, and the problem that traditional concrete is not easy to pour in a narrow space is solved.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention belongs to the field of backfilling construction of extra trenches in a foundation pit, and particularly relates to a fluidized hardened soil backfilling system and construction method for narrow extra trenches in a pit.

Background Art

[0002] The extra trench refers to the space between the foundation, the outer wall of the basement, and the inner wall of the foundation pit support structure, and provides a working surface for building construction. In construction projects, the excavation range of the foundation pit is restricted by factors such as the land use limit line, underground pipe network, and geological conditions. In terms of usage functions, buildings often require a larger usable area. To make full use of the underground space, the width of the extra trench in the foundation pit becomes smaller, the foundation pit becomes deeper, and the narrowest part of some construction extra trenches is less than 50 cm, greatly increasing the difficulty of backfilling the extra trench in the foundation pit. Construction agencies often focus on the quality of the main structure construction and ignore the control of the backfill soil in the extra trench, resulting in the formation of damages such as cracks due to uneven settlement of various pipes laid in the extra trench, causing unnecessary economic losses. The selection of backfill materials and construction quality for the extra trench are very important for foundation safety, normal use of pipes, and the stability of the entire building. With the occurrence of narrow extra trenches, ordinary soil caving solid backfill materials cannot be used because there is no ramming working space.

[0003] Some of the reasons for the complexity of the earthwork backfilling construction in the foundation pit are that currently, the above-ground structure often adopts a cantilever structure, and its formwork support frame is often placed on the backfill soil. Without reasonable control measures, there are potential risks such as settlement of the formwork support frame foundation.

[0004] In recent years, construction accidents due to the quality of redundant trench backfilling often involve water, especially in mountainous areas. When encountering heavy rain or when water cannot be smoothly discharged on the ground and seeps into the redundant trench, it not only causes the settlement of the backfilled soil retaining wall but also easily leads to the floating accident of the underground structure.

[0005] Therefore, in order to avoid safety problems such as soil settlement, pipe rupture, and underground structure floating caused by the uneven settlement of the soil mass during the construction of narrow redundant trenches in the foundation pit, and to enable the normal construction of the entire upper structure, avoid the situation where the backfilling construction of the redundant trench occupies an important route, and avoid the influence of the reserved post-injection zone of the basement structure penetration on the overall structural integrity, it is necessary to research and develop a fluidized hardened soil backfilling system and construction method for narrow redundant trenches.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The object of the present invention is to provide a fluidized hardened soil backfilling system and construction method for narrow redundant trenches in the foundation pit in order to overcome the drawbacks in the prior art.

Means for Solving the Problems

[0007] Such a fluidized hardened soil backfilling system for narrow redundant trenches in the foundation pit includes a foundation pit excavation enclosure system in the foundation pit, a redundant trench floor slab reserved post-injection zone system, a redundant trench ground reinforcement system, a redundant trench pipe deformation prevention support system, and a basement waterproof system. The foundation pit excavation enclosure system in the foundation pit includes a first foundation pit, a second foundation pit, a first support retaining pile, a second support retaining pile, and a shotcrete layer. The first foundation pit adopts a structure surrounding the first support retaining pile, and a cushion layer is laid at the bottom of the foundation pit. The second foundation pit adopts a structure surrounding the second support retaining pile and the shotcrete layer after slope excavation, and a cushion layer is laid at the bottom of the foundation pit. A bottom plate is provided at the bottom of the second foundation pit. The extra grooved floor slab reserved post-injection zone system includes a first extra groove, a second extra groove, a first floor slab, a second floor slab, a post-injection zone, and a temporary support steel plate. A first outer wall is provided between the end of the first floor slab and the end of the second floor slab, and a second outer wall is provided between the end of the second floor slab and the end of the bottom plate. The first extra groove is located between the first outer wall and the first support pile. The second extra groove is located between the second outer wall, the second support pile, and the shotcrete layer. The post-injection zone is installed on the second floor slab above the second extra groove. The temporary support steel plate is laid at both ends of the post-injection zone.

[0008] Preferably, a formwork support system for constructing the first floor slab is further provided in the first foundation pit, and the formwork support system supports on the second floor slab and the temporary support steel plate.

[0009] Preferably, a first reserved steel bar and a second reserved steel bar are respectively provided at both ends of the post-injection zone, and a first reserved waterproof coil material and a second reserved waterproof coil material are respectively provided below.

[0010] Preferably, the extra groove ground reinforcement system includes a first steel pipe pile, a second steel pipe pile, a third steel pipe pile, and fluidized hardened backfill soil. The first steel pipe pile is buried in the bottom of the first extra groove, and the top is at the same elevation as the outdoor floor surface. The second steel pipe pile is buried in the bottom of the second extra groove, and a corbel supported below the temporary support steel plate is provided at the top. The lower end of the third steel pipe pile is inserted into the second support pile through a reserved cup opening, and a corbel supported below the temporary support steel plate is provided at the top. The fluidized hardened backfill soil is injected into the first extra groove and the second extra groove.

[0011] Preferably, the extra groove pipe deformation prevention support system includes a pipeline, a flexible support plate, a support frame, and a flange band. The pipeline passes through the second support pile, the second extra groove, and the second outer wall in sequence. The flexible support plate is installed below the pipeline and fixed to the second steel pipe pile body by the support frame and the flange band.

[0012] Preferably, the basement waterproofing system includes a protective layer, a waterproof coil material, a leveling layer, a first water-blocking layer, and a second water-blocking layer. The protective layer, the waterproof coil material, and the leveling layer are sequentially provided below the bottom plate. The leveling layer is bonded to the cushion layer. The first water-blocking layer is located above the cushion layer of the first extra groove and is fixed to the first support pile by the first reinforcing bars. The second water-blocking layer is located above the cushion layer of the second extra groove and is fixed to the second support pile by the second reinforcing bars. The protective layer, the waterproof coil material, and the leveling layer in the basement waterproofing system extend sequentially from below the bottom plate to the outside of the second outer wall, the second floor slab, and the first outer wall.

[0013] The construction method of the fluidized hardened soil backfilling system for the narrow extra groove of the pit in such a pit is as follows. Step 1: Sequentially perform the construction of the first support pile, the excavation of the first foundation pit, the construction of the second support pile, the sloping of the shotcrete layer, and the excavation of the second foundation pit, the construction of the bottom plate and the second outer wall, the construction of the second floor slab, the reserved post-injection zone, and the first outer wall. Step 2: Drive the second steel pipe pile in the second extra groove, penetrate the flexible support plate through it, install the support frame and the flange band below the flexible support plate and fix them to the pile body of the second steel pipe pile, drive the third steel pipe pile, and insert it into the reserved cup opening of the second support pile. Step 3: Install the temporary support steel plate, apply the formwork support system, and construct the first floor slab. Step 4: Remove the corbels of the formwork support system, the temporary support steel plate, the second steel pipe pile, and the third steel pipe pile in sequence. Then, place the anti-seepage concrete at the bottom of the second extra groove to form the second water-blocking layer, fill and inject the fluidized hardened backfilling soil inside, and construct the basement waterproofing system. Step 5: Drive the first steel pipe pile in the first extra groove, place the anti-seepage concrete at the bottom to form the first water-blocking layer, fill and inject the fluidized hardened backfilling soil inside, and after leveling, make it consistent with the elevation of the outdoor floor surface.

[0014] Preferably, in step 3, it further includes attaching stopper bolts to both sides of the temporary support steel plate.

[0015] Preferably, in steps 4 and 5, it further includes filling and injecting fluidized hardened backfill soil into the first steel pipe pile, the second steel pipe pile, and the third steel pipe pile.

[0016] Preferably, in step 1, attach the second rebar to the bottom pile body of the second support pile, install a flexible support plate below the pipeline, construct the leveling layer, the waterproof coil material, and the protective layer as a waterproof system and install the first reserved waterproof coil material, attach the first rebar to the bottom pile body of the first support pile, construct the leveling layer, the waterproof coil material, and the protective layer as a waterproof system and install the second reserved waterproof coil material, install the first reserved rebar and the second reserved rebar at both ends of the post-injection zone. In step 4, the specific method of constructing the basement waterproof system is that after the fluidized hardened backfill soil in the second extra groove has hardened, construct the leveling layer at the post-injection zone position in sequence, weld the first reserved waterproof coil material and the second reserved waterproof coil material, construct the protective layer, pour the post-injection zone concrete, form the complete second floor slab and its waterproof system. When welding the first reserved waterproof coil material and the second reserved waterproof coil material, a plurality of hot melt gaskets are uniformly arranged in the lap area of the two by an infrared laser positioning device, the hot melt gaskets are heated by an ultrasonic welder to weld and fix the first reserved waterproof coil material and the second reserved waterproof coil material, and a running weld machine is adopted at the gap between the two boundaries for double slit welding and sealing.

Advantages of the Invention

[0017] The beneficial effects of the present invention are as follows.

[0018] 1) The present invention adopts the technology of reserved post-injection zone for the extra trench floor slab, and installs a temporary support steel plate in the post-injection zone as the temporary support of the formwork support system, so as to ensure the synchronous construction of the structural slabs on the same floor in different sections of the foundation pit. At the same time, it adopts fluidized hardened soil to fill back the second extra trench, further conducts the work of the second floor slab waterproof system, and finally conducts the work of the sealed post-injection zone, improving the construction efficiency and quality of the basement main body structure.

[0019] 2) The present invention adopts the technology of strengthening the extra trench ground, driving steel pipe piles in the extra trench, and filling back with fluidized hardened soil, so as to improve the compactness of filling back the extra trench in the foundation pit and solve the problem that it is difficult to place conventional concrete in a narrow space.

[0020] 3) The present invention adopts the technology of preventing deformation and supporting the extra trench piping, installs a flexible support plate, a support frame and a flange band under the pipeline, and combines measures such as strengthening the steel pipe piles and filling back with fluidized hardened soil to achieve a triple strengthening and deformation prevention effect, and can effectively prevent the piping deformation caused by uneven settlement of the extra trench ground soil.

[0021] 4) The present invention adopts the waterproof technology for the basement exterior wall, installs a protective layer, a waterproof coil material and a leveling layer on the outside of the structure, welds and strengthens the reserved waterproof coil material for the post-injection zone of the floor slab, and plants steel bars and installs a water barrier layer in the support and protection structure at the bottom of the extra trenches in different sections, so as to improve the anti-seepage characteristics of the whole basement structure and at the same time avoid the influence of the groundwater level on the extra trench area.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying out the Invention

[0023] Example 1 As an example, the fluidized hardened soil backfilling system for the narrow extra groove of the pit in such a pit includes a pit excavation enclosure system in the pit, a post-injection zone system for the extra grooved floor slab reservation, an extra groove ground reinforcement system, an extra groove pipe deformation prevention support system, and a basement waterproofing system.

[0024] The pit excavation enclosure system in the pit includes a first foundation pit 1, a second foundation pit 2, a first support pile 3, a second support pile 4, and a shotcrete layer 5. The first foundation pit 1 adopts a structure surrounding the first support pile 3, and a cushion layer 6 is laid at the bottom of the pit. The second foundation pit 2 adopts a structure surrounding the second support pile 4 and the shotcrete layer 5 after slope excavation, and a cushion layer 6 is laid at the bottom of the pit.

[0025] A formwork support system 34 for constructing a first floor slab 9 in the first foundation pit 1 is further provided, and the formwork support system 34 is supported on the already placed second floor slab 10 and a temporary support steel plate 12.

[0026] The above-mentioned extra groove floor slab post-injection zone system includes a first extra groove 7, a second extra groove 8, a first floor slab 9, a second floor slab 10, a post-injection zone 11, and a temporary support steel plate 12. The first extra groove 7 is located between the first outer wall 13 and the first retaining pile 3. The second extra groove 8 is located between the second outer wall 14, the second retaining pile 4, and the shotcrete layer 5. The post-injection zone 11 is installed on the second floor slab 10 above the second extra groove 8. The temporary support steel plate 12 is laid at both ends of the post-injection zone 11. A first reserved reinforcing bar 35 and a second reserved reinforcing bar 36 are respectively provided at both ends of the post-injection zone 11, and a first reserved waterproof coil material 37 and a second reserved waterproof coil material 38 are respectively provided below.

[0027] The above-mentioned extra groove ground strengthening system includes a first steel pipe pile 15, a second steel pipe pile 16, a third steel pipe pile 17, and fluidized hardened backfill soil 18. The first steel pipe pile 15 is buried in the bottom of the first extra groove 7, and its top is at the same elevation as the outdoor floor surface 19. The second steel pipe pile 16 is buried in the bottom of the second extra groove 8, and a corbel 20 supported below the temporary support steel plate 12 is provided at its top. The lower end of the third steel pipe pile 17 is inserted into the second retaining pile 4 through a reserved cup mouth 21, and a corbel 20 supported below the temporary support steel plate 12 is provided at its top. The fluidized hardened backfill soil 18 is injected into the first extra groove 7 and the second extra groove 8.

[0028] The above-mentioned extra groove pipe deformation prevention support system includes a pipeline 22, a flexible support plate 23, a support frame 24, and a flange band 25. The pipeline 22 passes through the second retaining pile 4, the second extra groove 8, and the second outer wall 14 in sequence. The flexible support plate 23 is installed below the pipeline 22 and is fixed to the body of the second steel pipe pile 16 by the support frame 24 and the flange band 25.

[0029] The basement waterproofing system includes a bottom plate 26, a first outer wall 13, a second outer wall 14, a protective layer 27, a waterproof coil material 28, a leveling layer 29, a first water-blocking layer 30, and a second water-blocking layer 31. The bottom plate 26 is provided at the bottom of the second foundation pit 2. The protective layer 27, the waterproof coil material 28, and the leveling layer 29 are sequentially installed below the bottom plate 26. The leveling layer 29 is bonded to the cushion layer 6. The first water-blocking layer 30 is located above the cushion layer 6 of the first extra groove 7 and is fixed to the first support retaining pile 3 by the first reinforcing bars 32. The second water-blocking layer 31 is located above the cushion layer 6 of the second extra groove 8 and is fixed to the second support retaining pile 4 by the second reinforcing bars 33. The protective layer 27, the waterproof coil material 28, and the leveling layer 29 in the basement waterproofing system extend sequentially from below the bottom plate 26 to the outside of the second outer wall 14, the second floor slab 10, and the first outer wall 13.

[0030] Example 2 As another example, the construction method of the fluidized hardened soil backfilling system for the narrow extra groove of the pit in such a pit includes the following steps.

[0031] As shown in FIG. 1, construct the first support retaining pile 3, excavate the first foundation pit 1 to the designed elevation, further construct the second support retaining pile 4, install a reserved cup opening 21 at the top of the pile, perform the operation of the shotcrete layer 5 after slope excavation to a certain depth, and then further excavate the second foundation pit 2 to the designed elevation.

[0032] After leveling the bottom of the second foundation pit 2, lay the cushion layer 6. In the bottom pile body of the second retaining pile 4, attach the second reinforcing bar 33 by methods such as chemical bar planting. Construct the leveling layer 29, waterproof coil material 28, and protective layer 27 as the waterproof system of the bottom plate. Construct the basement bottom plate 26 through processes such as support, steel bar binding, and concrete pouring. Then, construct the second outer wall 14. On the outside, construct the leveling layer 29, waterproof coil material 28, and protective layer 27 as the waterproof system of the second outer wall, and install the first reserved waterproof coil material 37 at the top of the wall. During that period, install the flexible support plate 23 below the pipeline 22 and temporarily fix it between the second retaining pile 4 and the second outer wall 14 for opposing support.

[0033] Lay the cushion layer 6 at the bottom of the first foundation pit 1. Attach the first reinforcing bar 32, construction leveling layer 29, waterproof coil material 28, and protective layer 27 as the waterproof system of the second floor slab to the bottom pile body of the first retaining pile 3, and install the second reserved waterproof coil material 38. Then, construct the second floor slab 10 and the first outer wall 13. Here, reserve the post-injection zone 11 on the second floor slab 10 above the second extra groove 8, and install the first reserved steel bar 35 and the second reserved steel bar 36 at both ends of the post-injection zone 11 when binding the steel bars of the second floor slab 10.

[0034] Drive the second steel pipe pile 16 in the second extra groove 8, penetrate the flexible support plate 23 through it, attach the support frame 24 and the flange band 25 below the flexible support plate 23, and fix the flexible support plate 23 to the pile body of the second steel pipe pile 16 by tightening the bolts of the flange band 25, as shown in Figure 3. Subsequently, drive the third steel pipe pile 17 and insert it into the reserved cup opening 21 of the second retaining pile 4, ensuring that the tops of the second steel pipe pile 16 and the third steel pipe pile 17 are flush with the upper surface of the second floor slab 10.

[0035] As shown in FIGS. 1 and 4, flat steel plates are laid at both ends of the post-injection zone 11 as temporary support steel plates 12. In order to prevent the occurrence of offsets in the temporary support steel plates 12, stopper bolts 41 may be embedded on both sides thereof for restriction. Thereafter, a footing is established in the first foundation pit 1 as a formwork support system 34 for constructing the first floor slab 9, the first floor slab 9 is placed and completed, ensuring the synchronous construction of structural slabs on the same floor in different sections of the foundation pit.

[0036] As shown in FIG. 2, the formwork support system 34 and the temporary support steel plates 12 are removed in sequence, the corbels 20 of the second steel pipe pile 16 and the third steel pipe pile 17 are cut, and after cutting, it is ensured that the top ends of the second steel pipe pile 16 and the third steel pipe pile 17 are flush with the cushion layer 6 of the first foundation pit 1. As shown in FIG. 6, thereafter, anti-seepage concrete is placed at the bottom of the second extra groove 8 to form the second water barrier layer 31, and fluidized hardened backfill soil is adopted to fill the second steel pipe pile 16, the third steel pipe pile 17 and the second extra groove 8. As shown in FIG. 5, after the fluidized hardened backfill soil 18 in the second extra groove 8 has hardened, a leveling layer 29 is constructed at the position of the post-injection zone 11 in sequence, the first reserved waterproof coil material 37 and the second reserved waterproof coil material 38 are welded, a protective layer 27 is constructed, the post-injection zone 11 concrete is placed, and a complete second floor slab 10 and its waterproof system are formed. Here, when welding the first reserved waterproof coil material 37 and the second reserved waterproof coil material 38, a plurality of hot melt gaskets 39 are uniformly arranged in the lap area of both by an infrared laser positioning device, and the hot melt gaskets 39 are heated by an ultrasonic welder to weld and fix the first reserved waterproof coil material 37 and the second reserved waterproof coil material 38, and a running welder 40 is adopted for double slit welding and sealing at the gap at the boundary between the two.

[0037] As shown in FIGS. 2 and 7, the first steel pipe pile 15 is driven in the first extra groove 7, anti-seepage concrete is placed at the bottom to form the first water barrier layer 30, and fluidized hardening backfill is adopted to fill the first steel pipe pile 15 and the first extra groove 7. The first extra groove 7 after being backfilled and leveled is flush with the elevation of the outdoor floor surface 19.

[0038] Finally, after all the foundation pits are constructed and completed, the work on the superstructure is subsequently carried out.

Explanation of Signs

[0039] 1 First foundation pit 2 Second foundation pit 3 First retaining pile 4 Second retaining pile 5 Shotcrete layer 6 Cushion layer 7 First extra groove 8 Second extra groove 9 First floor slab 10 Second floor slab 11 Post-injection zone 12 Temporary support steel plate 13 First outer wall 14 Second outer wall 15 First steel pipe pile 16 Second steel pipe pile 17 Third steel pipe pile 18 Fluidized hardened backfill soil 19 Outdoor floor surface 20 Corbels 21 Reserved cup opening 22 Pipeline 23 Flexible support plate 24 Support frame 25 Flange band 26 Bottom plate 27 Protective layer 28 Waterproof coil material 29 Levelling layer 30 First water barrier layer 31 Second water barrier layer 32 First implanted steel bar 33 Second implanted steel bar 34 Formwork support system 35 First reserved steel bar 36 Second reserved steel bar 37 First reserved waterproof coil material 38 Second reserved waterproof coil material 39 Hot melt gasket 40 Traveling welding machine 41 Stopper bolt

Claims

1. A system for backfilling fluidized hardened soil in a narrow extra groove of a pit in a pit, including a pit excavation enclosure system in the pit, an extra groove floor slab reservation post-injection zone system, an extra groove ground reinforcement system, an extra groove pipe deformation prevention support system, and a basement waterproofing system. The pit excavation enclosure system in the pit includes a first foundation pit, a second foundation pit, a first support pile, a second support pile, and a shotcrete layer. The first foundation pit adopts a structure surrounding the first support pile, and a cushion layer is laid at the bottom of the pit. The second foundation pit adopts a structure surrounding the second support pile and the shotcrete layer after slope excavation, and a cushion layer is laid at the bottom of the pit. A bottom slab is provided at the bottom of the second foundation pit. The extra groove floor slab reservation post-injection zone system includes a first extra groove, a second extra groove, a first floor slab, a second floor slab, a post-injection zone, and a temporary support steel plate. A first outer wall is provided between the ends of the first floor slab and the ends of the second floor slab. A second outer wall is provided between the ends of the second floor slab and the ends of the bottom slab. The first extra groove is located between the first outer wall and the first support pile. The second extra groove is located between the second outer wall, the second support pile, and the shotcrete layer. The post-injection zone is installed on the second floor slab above the second extra groove. The temporary support steel plate is laid at both ends of the post-injection zone. A system for backfilling fluidized hardened soil in a narrow extra groove of a pit in a pit, characterized by the above.

2. A formwork support system for constructing the first floor slab in the first foundation pit is further provided. The formwork support system supports on the second floor slab and the temporary support steel plate. A system for backfilling fluidized hardened soil in a narrow extra groove of a pit in a pit according to Claim 1, characterized by the above.

3. A first reserved steel bar and a second reserved steel bar are respectively provided at both ends of the post-injection zone, and a first reserved waterproof coil material and a second reserved waterproof coil material are respectively provided below. A system for backfilling fluidized hardened soil in a narrow extra groove of a pit in a pit according to Claim 1, characterized by the above.

4. The extra trench ground reinforcement system includes a first steel pipe pile, a second steel pipe pile, a third steel pipe pile, and fluidized hardened backfill soil. The first steel pipe pile is buried in the bottom of the first extra trench, and its top is at the same elevation as the outdoor floor surface. The second steel pipe pile is buried in the bottom of the second extra trench, and a corbel supported below the temporary support steel plate is provided at its top. The lower end of the third steel pipe pile is inserted into the second support pile through a reserved cup opening, and a corbel supported below the temporary support steel plate is provided at its top. The fluidized hardened backfill soil is injected into the first extra trench and the second extra trench. The fluidized hardened soil backfilling system for the narrow extra trench of the pit according to claim 1, characterized in that.

5. The extra trench pipe deformation prevention support system includes a pipeline, a flexible support plate, a support frame, and a flange band. The pipeline passes through the second support pile, the second extra trench, and the second outer wall in sequence. The flexible support plate is installed below the pipeline and fixed to the second steel pipe pile body by the support frame and the flange band. The fluidized hardened soil backfilling system for the narrow extra trench of the pit according to claim 1, characterized in that.

6. The basement waterproofing system includes a protective layer, a waterproof coil material, a leveling layer, a first water barrier layer, and a second water barrier layer. The protective layer, the waterproof coil material, and the leveling layer are provided in sequence below the bottom plate. The leveling layer is bonded to the cushion layer. The first water barrier layer is located above the cushion layer of the first extra trench and fixed to the first support pile by the first reinforcing bars. The second water barrier layer is located above the cushion layer of the second extra trench and fixed to the second support pile by the second reinforcing bars. The protective layer, the waterproof coil material, and the leveling layer in the basement waterproofing system extend in sequence from below the bottom plate to the outside of the second outer wall, the second floor slab, and the first outer wall. The fluidized hardened soil backfilling system for the narrow extra trench of the pit according to claim 1, characterized in that.

7. A construction method for the fluidized hardened soil backfilling system for the narrow extra trench of the pit according to any one of claims 1 to 6, Step 1 of sequentially performing the construction of the first support pile, the excavation of the first foundation pit, the construction of the second support pile, the sloping of the shotcrete layer and the excavation of the second foundation pit, the construction of the bottom plate and the second outer wall, the second floor slab, the reserved post-injection zone, and the first outer wall. Drive the second steel pipe pile in the second extra groove, penetrate the flexible support plate through it, attach the support frame and the flange band below the flexible support plate and fix them to the second steel pipe pile body, drive the third steel pipe pile, and insert it into the reserved cup opening of the second support pile, step 2; Install the temporary support steel plate, apply the formwork support system, and construct the first floor slab, step 3; Remove the corbels of the formwork support system, the temporary support steel plate, the second steel pipe pile and the third steel pipe pile in sequence. Then, place anti-seepage concrete at the bottom of the second extra groove to form the second waterproof layer, fill and inject fluidized hardened backfill soil inside, and construct the basement waterproof system, step 4; Drive the first steel pipe pile in the first extra groove, place anti-seepage concrete at the bottom to form the first waterproof layer, fill and inject fluidized hardened backfill soil inside, and after leveling, make it coincide with the elevation of the outdoor floor surface, step 5. The construction method of the fluidized hardened soil backfilling system for the narrow extra groove of the pit in the pit is characterized by including the above steps.

8. The construction method of the fluidized hardened soil backfilling system for the narrow extra groove of the pit according to claim 7, further including attaching stopper bolts on both sides of the temporary support steel plate in step 3.

9. The construction method of the fluidized hardened soil backfilling system for the narrow extra groove of the pit according to claim 7, further including filling and injecting fluidized hardened backfill soil into the first steel pipe pile, the second steel pipe pile and the third steel pipe pile in steps 4 and 5.

10. In step 1, attach the second rebar to the bottom pile body of the second support pile, install a flexible support plate below the pipeline, construct the leveling layer, waterproof coil material and protective layer as a waterproof system and install the first reserved waterproof coil material, attach the first rebar to the bottom pile body of the first support pile, construct the leveling layer, waterproof coil material and protective layer as a waterproof system and install the second reserved waterproof coil material, install the first reserved steel bar and the second reserved steel bar at both ends of the post-injection zone. In step 4, the specific method for constructing the basement waterproof system is that after the fluidized hardened backfill soil in the second extra groove has hardened, construct the leveling layer at the post-injection zone position in sequence, weld the first reserved waterproof coil material and the second reserved waterproof coil material, construct the protective layer, place the post-injection zone concrete, and form a complete second floor slab and its waterproof system. When welding the first reserved waterproof coil material and the second reserved waterproof coil material, a plurality of hot melt gaskets are uniformly arranged in the lap area of the two by an infrared laser positioning device, the hot melt gaskets are heated by an ultrasonic welder to weld and fix the first reserved waterproof coil material and the second reserved waterproof coil material, and a walking welder is adopted at the gap between the two boundaries for double slit welding and sealing. The construction method of the fluidized hardened soil backfill system for the narrow extra groove of the pit in the pit according to claim 7, characterized in that.

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