Construction method for reducing top load of underground garage

Abstract

The present invention belongs to the technical field of underground structure construction, and specifically relates to a construction method for reducing the top load of an underground garage, comprising the following steps: S1, water reservoir construction; S2, underground garage structure construction; S3, prefabricated concrete box production and installation; S4, drainage pipe and water supply pipeline construction; S5, retaining wall side foundation pit backfilling; S6, greening planting soil and concrete pavement construction; S7, sprinkler pipeline construction. The present invention can enhance the bearing stability of the underground garage roof, improve the drainage and water storage capacity of the underground garage top covering soil, and reduce the adverse effects of noise and temperature on the interior of the underground garage, thereby improving the environmental adaptability of the underground garage.

Description

Technical Field

[0001] The invention belongs to the technical field of underground structure construction, and in particular relates to a construction method for reducing the top load of an underground garage. Background Art

[0002] In order to improve the safety of underground garages, stabilize the roof structure of underground garages, and avoid direct damage to the roof of underground garages by external factors, most underground garage roof structures need to be covered with soil after construction is completed. The thickness of the covering soil is generally 200-400mm. However, according to the different uses of underground garages, the thickness of the covering soil on the roof of underground garages is also different. For underground garages with special functional positioning such as landscape parks, in order to meet the burial depth of municipal pipelines and the needs of garden planting, the thickness of the covering soil will reach 1200-1500mm. In this case, the bearing capacity of the roof of the underground garage will be greatly increased. At the same time, in order to ensure the normal growth of seedlings, sufficient irrigation water is essential. If water resources are stored in the soil layer for a long time and cannot be discharged, it will further increase the bearing capacity of the roof of the underground garage, seriously affecting the structural bearing performance and safety reliability of the underground garage.

[0003] Chinese patent CN113404063A discloses a basement roof backfill structure and construction process, the backfill structure includes several backfill layers arranged above the basement roof, the several backfill layers are laid in order from the basement roof upward, and the several backfill layers include an extruded polystyrene foam board cushion layer. The patent uses extruded polystyrene foam board instead of backfill soil, which has small compression deformation and stable chemical properties in water and soil, but the compressive strength of the underground garage roof is poor, and the top cannot withstand a large load. When heavy objects are piled up, the extruded polystyrene board is easily squeezed and damaged. At the same time, due to the insufficient thickness of the top soil cover, the water storage capacity of the soil cover is low during rain or greening irrigation, and the water accumulated inside the soil cover cannot be drained away, resulting in frequent ground water accumulation problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a construction method for reducing the load on the top of an underground garage, which can enhance the bearing stability of the roof of the underground garage, improve the drainage and water storage capacity of the covering soil on the top of the underground garage, and at the same time reduce the adverse effects of noise and temperature on the interior of the underground garage, thereby improving the environmental adaptability of the underground garage.

[0005] The construction method for reducing the top load of an underground garage according to the present invention comprises the following steps:

[0006] S1. Water reservoir construction

[0007] Determine the location of the water reservoir according to the design drawings of the underground garage, reserve water holes in the retaining wall, and the height of the water holes is greater than the height of the bottom of the reservoir;

[0008] Select a water pump of a suitable model and install it at the bottom of the reservoir. A water supply pipe is provided on the water pump. The end of the water supply pipe away from the water pump passes through the retaining wall through the water outlet hole.

[0009] S2. Underground garage structure construction

[0010] According to the reserved clamp positions determined in the design drawings of the underground garage, several reserved clamps are vertically arranged on the side of the retaining wall close to the water reservoir;

[0011] According to the position of the drainage hole 1 determined in the design drawing of the underground garage, the drainage hole 1 is set on the roof of the garage, and the leveling layer, the slope layer and the waterproof layer are laid on the roof of the garage in sequence to form the garage roof, and the drainage hole 2 is set on the garage roof in coordination with the drainage hole 1;

[0012] S3. Production and installation of prefabricated concrete boxes

[0013] The top height of the precast concrete box is determined according to the top soil cover height of the garage determined by the underground garage design drawing. The top height of the precast concrete box is less than the top soil cover height of the garage.

[0014] The prefabricated concrete box includes a box wall, a bottom plate and a top plate. Drainage slots are pre-arranged on the box wall, the bottom plate and the top plate according to the drainage slot layout determined by the underground garage design drawings;

[0015] Pre-embed steel bar lifting rings at the top of the precast concrete box 200-500mm away from both sides, pour concrete, and complete the production of the precast concrete box after the concrete is formed;

[0016] Install the prefabricated concrete boxes and waterproof the joints of adjacent prefabricated concrete boxes;

[0017] S4. Construction of drainage pipes and water supply pipes

[0018] According to the drainage pipe layout determined by the underground garage design drawings, the drainage pipe is passed through the precast concrete box, the garage roof and the garage top plate in sequence. One end of the drainage pipe is provided with several groups of water inlets, which penetrate the top plate of the precast concrete box and are equipped with a water filter. The other end of the drainage pipe is provided with a group of water outlets, which extend into the water reservoir and have a height greater than the height of the water outlet hole. The drainage pipe is supported by the precast concrete box, the garage roof, the garage top plate and the reserved clamps.

[0019] After the water supply pipe passes through the retaining wall, it is installed from the bottom to the top along the outer wall of the retaining wall. After the installation is completed, the height of the top of the water supply pipe is greater than the designed ground elevation;

[0020] S5. Backfilling of the retaining wall side foundation pit

[0021] Use foamed concrete as backfill material, and backfill the retaining wall side foundation pit layer by layer with a thickness of 500-1000mm per layer until the top elevation of the foamed concrete is the same as the top elevation of the precast concrete box;

[0022] S6. Construction of greening soil and concrete pavement

[0023] Determine the greening planting soil area, use plain soil as the backfill material, start backfilling from the top elevation of the prefabricated concrete box and the top elevation of the foamed concrete, until backfilling to the bottom design elevation of the greening planting soil, the backfill thickness is between 200-1000mm, and after the plain soil backfill is completed, carry out greening planting;

[0024] Determine the concrete pavement area, use plain soil as the backfill material, start backfilling from the top elevation of the precast concrete box and the top elevation of the foamed concrete, until backfilling to the bottom design elevation of the concrete pavement, the backfill thickness is between 200-1000mm, after the plain soil backfill is completed, pour concrete to form a concrete pavement, after pouring, carry out moisture maintenance on the concrete pavement;

[0025] S7. Spray pipe construction

[0026] One end of the water supply pipe extending out of the ground is connected with a sprinkler pipe, and the sprinkler pipe is continuously laid along the green planting soil and the concrete pavement.

[0027] Preferably, in step S1, the length and width of the water reservoir are both between 1.5-3m, the aperture of the water outlet hole is between 100-200mm, the height of the water outlet hole is 100-500mm higher than the height of the bottom of the water reservoir, and a garage raft is provided at one end of the water reservoir away from the retaining wall, and the height of the bottom of the water reservoir is 1-2m lower than the height of the garage raft.

[0028] Preferably, in step S2, the shape of the reserved clamp is Ω-shaped as a whole, the depth of the reserved clamp embedded in the retaining wall is 150-200 mm, and the distance between adjacent reserved clamps is between 1-2 m.

[0029] Preferably, in step S3, the precast concrete box is arranged as a hollow cuboid as a whole, the length and width of the precast concrete box are both between 2-5m, the thickness of the box wall, the thickness of the bottom plate and the thickness of the top plate are all between 100-200mm, the precast concrete box is made of concrete with a strength grade of C30-C40, and the diameter of the steel bar eye is 20-25mm.

[0030] Preferably, in step S3, a truck crane is used to hook the hook of the truck crane on the steel bar lifting ring on the top of the precast concrete box, and the edge of one side of the garage roof is used as the starting point to sequentially install the precast concrete box toward the other side of the garage roof. The joints between adjacent precast concrete boxes are plugged with water stop strips, the insertion depth of the water stop strips is ≥500mm, and the water expansion rate of the water stop strips is 300%.

[0031] Preferably, in step S3, when waterproofing the joints of adjacent prefabricated concrete boxes, firstly, the non-curing rubber asphalt waterproof coating is brushed from the middle of the joint to both sides, with a brushing width of ≥250mm, and then the asphalt waterproof membrane is laid on the non-curing rubber asphalt waterproof coating, the width of the asphalt waterproof membrane is equal to the brushing width of the non-curing rubber asphalt waterproof coating, and the asphalt waterproof membrane adopts SBS modified asphalt root penetration resistant waterproof membrane, and the thickness of the SBS modified asphalt root penetration resistant waterproof membrane is 3-5mm.

[0032] Preferably, in step S4, the height of the water outlet is 100-500mm greater than the height of the water outlet hole, the distance between the water outlet and the retaining wall is 50-100mm, the height of the top of the water supply pipe exceeds the ground design elevation by 50-150mm, the diameter of the drainage pipe is 100-200mm, and the diameter of the water supply pipe is 50-150mm. The drainage pipe adopts a rigid polyvinyl chloride pipe, a random copolymer polypropylene pipe, an aluminum-plastic composite pipe, a thin-walled stainless steel pipe, a hot-dip galvanized steel pipe, a welded steel pipe or a cast iron pipe, and the water supply pipe adopts a stainless steel pipe, a PVC pipe, a PP-R pipe, a hot-dip galvanized steel pipe, a welded steel pipe or a cast iron pipe.

[0033] Preferably, in step S5, the density of the foamed concrete is 950-1050 kg / m³, and the compressive strength of the foamed concrete is 9-12 MPa.

[0034] Preferably, in step S6, when the concrete pavement is in a normal temperature environment, the concrete pavement is moisturized and maintained by covering it with a plastic film for 13-15 days; when the concrete pavement is in a negative temperature environment, the concrete pavement is moisturized and maintained by covering it with a plastic film and mineral wool felt for 13-15 days.

[0035] Preferably, in step S7, the diameter of the spray pipe is 50-150 mm, a spray head is arranged at intervals of 1-3 m, and the spray radiation area radius of the spray head is between 500-1000 mm. The spray pipe is made of stainless steel pipe, PVC pipe, PP-R pipe, hot-dip galvanized steel pipe, welded steel pipe or cast iron pipe.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The garage roof is partially covered with prefabricated concrete boxes, which not only meets the construction requirements and improves the construction efficiency, but also ensures the structural safety of the garage roof. Non-curing rubber asphalt waterproof coating, asphalt waterproof membrane and water stop strips are installed at the joints of adjacent prefabricated concrete boxes to solve the problem of water leakage at the joints of adjacent prefabricated concrete boxes and ensure the waterproof effect of the joints of adjacent prefabricated concrete boxes.

[0038] (2) The precast concrete box is designed as a hollow rectangular block. The internal cavity can form a sound insulation layer, which helps to reduce the propagation of sound. When a vehicle passes over the top of the underground garage, it can reduce the noise transmitted to the underground garage, thereby improving the environmental adaptability of the underground garage. In addition, the internal cavity of the precast concrete box can form a heat insulation barrier, reducing the heat exchange between the outside air and the internal space of the underground garage, thereby improving the insulation effect of the underground garage and ensuring the internal temperature of the underground garage when the temperature drops sharply in winter.

[0039] (3) Foamed concrete has low density, high fluidity and self-compacting properties. Using foamed concrete to backfill the side pit of the retaining wall can improve the backfill quality and reduce the lateral pressure exerted by the backfill soil on the retaining wall. At the same time, it can evenly wrap the water supply pipes to avoid the traditional backfill soil from being squeezed and damaged by the water supply pipes due to settlement or uneven compaction. After hardening, the foamed concrete and the precast concrete box share the upper load, enhancing the overall bearing capacity of the underground garage roof. The hardened foamed concrete forms a closed microporous structure with strong thermal insulation and impermeability, which can reduce the impact of external temperature changes on the precast concrete box and water supply pipes, and provide reliable protection for the precast concrete box and water supply pipes.

[0040] (4) Drain hole 1, drain hole 2 and drainage trough holes are reserved on the garage roof, garage roof and precast concrete box respectively to prepare for the later installation of drainage pipes. The water resources from the green planting soil and concrete pavement flow to the reservoir through the drainage pipes, thereby reducing the bearing capacity of the garage roof. The drainage pipes, reservoirs, water pumps, water supply pipes and sprinkler pipes cooperate with each other to ensure the effective collection and recycling of water resources.

[0041] The present invention can enhance the bearing stability of the roof of the underground garage, improve the drainage capacity of the soil covering the top of the underground garage, and at the same time improve the environmental adaptability of the underground garage. The construction method is simple to operate and is safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the structure of the present invention;

[0043] Figure 2 yes Figure 1 The enlarged schematic diagram of point A in the middle;

[0044] Figure 3 yes Figure 1 The enlarged schematic diagram of point B in the middle;

[0045] Figure 4 yes Figure 1 The enlarged schematic diagram of the center C;

[0046] Figure 5 It is a partial structural schematic diagram of the prefabricated concrete box, water stop strip, non-curing rubber asphalt waterproof coating and asphalt waterproof membrane in the present invention;

[0047] Figure 6 It is a partial structural schematic diagram of the prefabricated concrete box, steel bar hanging ring, drainage slot hole, water filter and drainage pipe in the present invention;

[0048] Figure 7 It is a partial structural schematic diagram of the present invention in which the water stop strip, the non-curing rubber asphalt waterproof coating, the asphalt waterproofing membrane and the water filter are removed;

[0049] In the figure:

[0050] 1. Sprinkler head; 2. Garage raft; 3. Reservoir; 4. Retaining wall; 5. Water outlet hole; 6. Water pump; 7. Water supply pipe; 8. Reserved clamp; 9. Drain hole one; 10. Garage top plate; 11. Garage roof; 12. Precast concrete box; 13. Steel bar hanging ring; 14. Drain trough hole; 15. Water stop strip; 16. Non-curing rubber asphalt waterproof coating; 17. Asphalt waterproof membrane; 18. Drain pipe; 19. Water filter; 20. Foamed concrete; 21. Sprinkler pipe; 22. Drain hole two. DETAILED DESCRIPTION

[0051] The present invention is specifically described and illustrated below in conjunction with embodiments.

[0052] Example 1

[0053] like Figure 1-7 As shown, the construction method for reducing the top load of the underground garage described in this embodiment includes the following steps:

[0054] S1, Reservoir 3 construction

[0055] The position of the water reservoir 3 is determined according to the design drawings of the underground garage, and a water outlet hole 5 is reserved in the retaining wall 4, and the height of the water outlet hole 5 is greater than the height of the bottom of the water reservoir 3;

[0056] Select a water pump of a suitable type, install a water pump 6 at the bottom of the water reservoir 3, and arrange a water supply pipe 7 on the water pump 6. The end of the water supply pipe 7 away from the water pump 6 passes through the retaining wall 4 through the water outlet hole 5;

[0057] S2. Underground garage structure construction

[0058] According to the reserved clamp 8 position determined by the design drawing of the underground garage, a plurality of reserved clamps 8 are vertically arranged on one side of the retaining wall 4 close to the reservoir 3;

[0059] According to the position of the drainage hole 9 determined in the design drawing of the underground garage, a drainage hole 9 is set on the garage roof 10, and a leveling layer, a slope layer and a waterproof layer are laid in sequence to form a garage roof 11. A drainage hole 22 is set on the garage roof 11 to match the drainage hole 9;

[0060] S3, production and installation of prefabricated concrete box 12

[0061] According to the garage top soil cover height determined by the underground garage design drawing, the top height of the precast concrete box 12 is determined, and the top height of the precast concrete box 12 is less than the garage top soil cover height;

[0062] The prefabricated concrete box 12 includes a box wall, a bottom plate and a top plate. The drainage slots 14 are arranged in advance on the box wall, the bottom plate and the top plate according to the layout of the drainage slots 14 determined by the design drawings of the underground garage.

[0063] Pre-embed steel bar lifting rings 13 at the top of the precast concrete box 12 at 200-500mm from both sides, pour concrete, and complete the production of the precast concrete box 12 after the concrete is formed;

[0064] Install the prefabricated concrete boxes 12 and waterproof the joints of adjacent prefabricated concrete boxes 12;

[0065] S4, construction of drainage pipe 18 and water supply pipe 7

[0066] According to the layout of the drainage pipe 18 determined by the design drawing of the underground garage, the drainage pipe 18 is passed through the precast concrete box 12, the garage roof 11 and the garage top plate 10 in sequence. One end of the drainage pipe 18 is provided with a plurality of water inlets, which penetrate the top plate of the precast concrete box 12 and are matched with a water filter 19. The other end of the drainage pipe 18 is provided with a group of water outlets, which extend into the interior of the water reservoir 3 and whose height is greater than that of the water outlet hole 5. The drainage pipe 18 is supported by the precast concrete box 12, the garage roof 11, the garage top plate 10 and the reserved clamp 8;

[0067] After the water supply pipe 7 passes through the retaining wall 4, it is installed along the outer wall of the retaining wall 4 from the bottom to the top. After the installation is completed, the height of the top of the water supply pipe 7 is greater than the designed elevation of the ground;

[0068] S5, Backfilling of foundation pit on side 4 of retaining wall

[0069] Use foamed concrete 20 as backfill material, and backfill the foundation pit on the 4 sides of the retaining wall in layers with a thickness of 500-1000mm per layer until the top elevation of the foamed concrete 20 is the same as the top elevation of the prefabricated concrete box 12;

[0070] S6. Construction of greening soil and concrete pavement

[0071] Determine the greening planting soil area, use plain soil as backfill material, start backfilling from the top elevation of the prefabricated concrete box 12 and the top elevation of the foamed concrete 20 that have been completed, until backfilling to the bottom design elevation of the greening planting soil, the backfill thickness is between 200-1000mm, and when the plain soil backfill is completed, carry out greening planting;

[0072] Determine the concrete pavement area, use plain soil as backfill material, start backfilling from the top elevation of the prefabricated concrete box 12 and the top elevation of the foamed concrete 20, until backfilling to the bottom design elevation of the concrete pavement, the backfill thickness is between 200-1000mm, after the plain soil backfill is completed, pour concrete to form a concrete pavement, after pouring, the concrete pavement is moisturized and maintained;

[0073] S7, spray pipe 21 construction

[0074] One end of the water supply pipe 7 extending out of the ground is connected to a spray pipe 21, and the spray pipe 21 is continuously laid along the green planting soil and the concrete road surface.

[0075] In step S1, the length and width of the water reservoir 3 are both between 1.5-3m, the aperture of the water outlet hole 5 is between 100-200mm, the height of the water outlet hole 5 is 100-500mm higher than the height of the bottom of the water reservoir 3, and a garage raft 2 is provided at one end of the water reservoir 3 away from the retaining wall 4, and the height of the bottom of the water reservoir 3 is 1-2m lower than the height of the garage raft 2.

[0076] In step S2, the shape of the reserved clamp 8 is Ω-shaped as a whole, the depth of the reserved clamp 8 embedded in the retaining wall 4 is 150-200 mm, and the distance between adjacent reserved clamps 8 is between 1-2 m.

[0077] In step S3, the precast concrete box 12 is configured as a hollow rectangular parallelepiped as a whole, the length and width of the precast concrete box 12 are both between 2-5m, the thickness of the box wall, the thickness of the bottom plate and the thickness of the top plate are all between 100-200mm, the precast concrete box 12 is made of concrete with a strength grade of C30-C40, and the diameter of the steel bar eye 13 is 20-25mm.

[0078] In step S3, a truck crane is used to hook the truck crane hook on the steel bar ring 13 on the top of the precast concrete box 12, and the edge of one side of the garage roof 10 is used as the starting point to sequentially install the precast concrete box 12 toward the other side of the garage roof 10. The joints between adjacent precast concrete boxes 12 are plugged with water stop strips 15, the insertion depth of the water stop strips 15 is ≥500mm, and the water expansion rate of the water stop strips 15 is 300%.

[0079] In step S3, when waterproofing the joints of adjacent prefabricated concrete boxes 12, firstly, the non-curing rubber asphalt waterproof coating 16 is brushed from the middle of the joint to both sides, and the brushing width is ≥250mm. Then, the asphalt waterproof membrane 17 is laid on the non-curing rubber asphalt waterproof coating 16. The width of the asphalt waterproof membrane 17 is equal to the brushing width of the non-curing rubber asphalt waterproof coating 16. The asphalt waterproof membrane 17 adopts SBS modified asphalt root penetration resistant waterproof membrane, and the thickness of the SBS modified asphalt root penetration resistant waterproof membrane is 3-5mm.

[0080] In step S4, the height of the water outlet is greater than the height of the water outlet hole 5 by 100-500 mm, the distance between the water outlet and the retaining wall 4 is 50-100 mm, the height of the top of the water supply pipe 7 exceeds the ground design elevation by 50-150 mm, the diameter of the drainage pipe 18 is 100-200 mm, and the diameter of the water supply pipe 7 is 50-150 mm. The drainage pipe 18 adopts a rigid polyvinyl chloride pipe, a random copolymer polypropylene pipe, an aluminum-plastic composite pipe, a thin-walled stainless steel pipe, a hot-dip galvanized steel pipe, a welded steel pipe or a cast iron pipe, and the water supply pipe 7 adopts a stainless steel pipe, a PVC pipe, a PP-R pipe, a hot-dip galvanized steel pipe, a welded steel pipe or a cast iron pipe.

[0081] In step S5, the density of the foamed concrete 20 is 950-1050 kg / m³, and the compressive strength of the foamed concrete 20 is 9-12 MPa.

[0082] In step S6, when the concrete pavement is at room temperature, the concrete pavement is moisturized and maintained by covering it with plastic film for 13-15 days. When the concrete pavement is at negative temperature, the concrete pavement is moisturized and maintained by covering it with plastic film and mineral wool felt for 13-15 days.

[0083] In step S7, the diameter of the spray pipe 21 is 50-150 mm, and a spray head 1 is arranged at intervals of 1-3 m in the spray pipe 21, and the spray radiation area radius of the spray head 1 is between 500-1000 mm. The spray pipe 21 is made of stainless steel pipe, PVC pipe, PP-R pipe, hot-dip galvanized steel pipe, welded steel pipe or cast iron pipe.

Claims

1. A construction method for reducing the top load of an underground garage, characterized in that: The following steps are involved: S1. Water reservoir (3) construction The position of the water reservoir (3) is determined, and a water outlet hole (5) is reserved in the retaining wall (4), wherein the height of the water outlet hole (5) is greater than the height of the bottom of the water reservoir (3); A water pump (6) is installed at the bottom of the water reservoir (3), and a water supply pipe (7) is arranged on the water pump (6). An end of the water supply pipe (7) away from the water pump (6) passes through the retaining wall (4) through the water outlet hole (5); S2. Underground garage structure construction A plurality of reserved clamps (8) are vertically arranged on one side of the retaining wall (4) close to the water reservoir (3); A first drainage hole (9) is provided on the garage roof (10), a leveling layer, a slope layer and a waterproof layer are laid in sequence to form a garage roof (11), and a second drainage hole (22) is provided on the garage roof (11) in coordination with the first drainage hole (9); S3. Fabrication and installation of prefabricated concrete boxes (12) Determine the top height of the prefabricated concrete box (12), the top height of the prefabricated concrete box (12) being less than the top soil height of the garage; The prefabricated concrete box (12) comprises a box wall, a bottom plate and a top plate, and drainage slots (14) are pre-arranged on the box wall, the bottom plate and the top plate; Pre-embed steel bar lifting rings (13) at the top of the prefabricated concrete box (12) at a distance of 200-500 mm from both sides, pour concrete, and complete the production of the prefabricated concrete box (12) after the concrete is formed; Performing installation work on the prefabricated concrete boxes (12) and waterproofing the joints between adjacent prefabricated concrete boxes (12); S4. Construction of drainage pipes (18) and water supply pipes (7) A drainage pipe (18) is passed through the precast concrete box (12), the garage roof (11) and the garage top plate (10) in sequence. A plurality of water inlets are provided at one end of the drainage pipe (18). The water inlets penetrate the top plate of the precast concrete box (12) and are provided with a water filter (19). A group of water outlets are provided at the other end of the drainage pipe (18). The water outlets extend into the interior of the water reservoir (3) and the height of the water outlets is greater than the height of the water outlet hole (5). The drainage pipe (18) is supported by the precast concrete box (12), the garage roof (11), the garage top plate (10) and the reserved clamp (8); After the water supply pipe (7) passes through the retaining wall (4), it is installed along the outer wall of the retaining wall (4) from the bottom to the top. After the installation is completed, the height of the top of the water supply pipe (7) is greater than the designed ground elevation; S5, retaining wall (4) side foundation pit backfill Using foamed concrete (20) as backfill material, backfill the side foundation pit of the retaining wall (4) in layers with a thickness of 500-1000 mm per layer until the top elevation of the foamed concrete (20) is the same as the top elevation of the prefabricated concrete box (12); S6. Construction of greening soil and concrete pavement Determine the greening planting soil area, use plain soil as backfill material, and start backfilling from the top elevation position of the prefabricated concrete box (12) and the top elevation position of the foamed concrete (20) that have been completed. The backfill thickness is between 200-1000mm. After the plain soil backfill is completed, greening planting is carried out; Determine the concrete pavement area, use plain soil as backfill material, start backfilling from the top elevation of the prefabricated concrete box (12) and the top elevation of the foamed concrete (20) that have been completed, and the backfill thickness is between 200-1000mm. After the plain soil backfill is completed, pour concrete to form a concrete pavement. After the pouring is completed, the concrete pavement is moisturized and maintained; S7. Sprinkler pipe (21) construction One end of the water supply pipe (7) extending out of the ground is connected to a spray pipe (21), and the spray pipe (21) is laid continuously along the greening planting soil and the concrete road surface.

2. The construction method for reducing the top load of an underground garage according to claim 1 is characterized in that: In step S1, the length and width of the water reservoir (3) are both between 1.5 and 3 m, the aperture of the water outlet hole (5) is between 100 and 200 mm, the height of the water outlet hole (5) is 100 to 500 mm higher than the height of the bottom of the water reservoir (3), a garage raft (2) is provided at one end of the water reservoir (3) away from the retaining wall (4), and the height of the bottom of the water reservoir (3) is 1 to 2 m lower than the height of the garage raft (2).

3. The construction method for reducing the top load of an underground garage according to claim 1 is characterized in that: In step S2, the shape of the reserved clamp (8) is Ω-shaped as a whole, the depth of the reserved clamp (8) embedded in the retaining wall (4) is 150-200 mm, and the distance between adjacent reserved clamps (8) is between 1-2 m.

4. The construction method for reducing the top load of an underground garage according to claim 1 is characterized in that: In step S3, the precast concrete box (12) is configured as a hollow rectangular parallelepiped as a whole. The length and width of the precast concrete box (12) are both between 2 and 5 m. The thickness of the box wall, the thickness of the bottom plate and the thickness of the top plate are all between 100 and 200 mm. The precast concrete box (12) is made of concrete with a strength grade of C30 to C40. The diameter of the steel bar eyelet (13) is 20 to 25 mm.

5. The construction method for reducing the top load of an underground garage according to claim 4 is characterized in that: In step S3, a mobile crane is used to hook the hook of the mobile crane onto the steel bar lifting ring (13) on the top of the precast concrete box (12), and the precast concrete box (12) is installed in sequence toward the other side of the garage roof (10) with the edge of one side of the garage roof (10) as the starting point. The joints of adjacent precast concrete boxes (12) are plugged with water stop strips (15), the insertion depth of the water stop strips (15) being ≥500 mm, and the water expansion rate of the water stop strips (15) being 300%.

6. The construction method for reducing the top load of an underground garage according to claim 5 is characterized in that: In step S3, when waterproofing the joints of adjacent prefabricated concrete boxes (12), the non-curing rubber asphalt waterproof coating (16) is firstly applied from the middle of the joint to both sides, with a brushing width of ≥250 mm, and then the asphalt waterproofing membrane (17) is laid on the non-curing rubber asphalt waterproof coating (16), the width of the asphalt waterproofing membrane (17) is equal to the brushing width of the non-curing rubber asphalt waterproof coating (16), and the asphalt waterproofing membrane (17) adopts SBS modified asphalt root puncture resistant waterproofing membrane, and the thickness of the SBS modified asphalt root puncture resistant waterproofing membrane is 3-5 mm.

7. The construction method for reducing the top load of an underground garage according to claim 1 is characterized in that: In step S4, the height of the water outlet is greater than the height of the water outlet hole (5) by 100-500 mm, the distance between the water outlet and the retaining wall (4) is 50-100 mm, the height of the top of the water supply pipe (7) exceeds the designed ground elevation by 50-150 mm, the diameter of the drainage pipe (18) is 100-200 mm, and the diameter of the water supply pipe (7) is 50-150 mm.

8. The construction method for reducing the top load of an underground garage according to claim 1, characterized in that: In step S5, the density of the foamed concrete (20) is 950-1050 kg / m³, and the compressive strength of the foamed concrete (20) is 9-12 MPa.

9. The construction method for reducing the top load of an underground garage according to claim 1, characterized in that: In step S6, when the concrete pavement is at room temperature, the concrete pavement is moisturized and maintained by covering it with plastic film for 13-15 days. When the concrete pavement is at negative temperature, the concrete pavement is moisturized and maintained by covering it with plastic film and mineral wool felt for 13-15 days.

10. The construction method for reducing the top load of an underground garage according to claim 1, characterized in that: In step S7, the diameter of the spray pipe (21) is 50-150 mm, a spray head (1) is arranged on the spray pipe (21) at intervals of 1-3 m, and the radius of the spray radiation area of ​​the spray head (1) is between 500-1000 mm.

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