A building core backfill structure constructed with the first floor slab installed and its construction method

Abstract

A method for constructing a building with a zero-floor slab as the initial backfill structure includes the following steps: Step 1, constructing the raft foundation and side columns; Step 2, constructing the zero-floor slab, leaving a manhole on it; Step 3, constructing the insulation and waterproofing layers; Step 4, constructing a new construction access road; Step 5, using machinery to construct the lower backfill layer; Step 6, manually backfilling the upper backfill layer; Step 7, excavating a trench in the upper backfill layer, and then laying a sand layer and a geotextile layer at the bottom of the trench; Step 8, placing drainage pipes in the trench and filling the area around the drainage pipes with a layer of crushed stone; Step 9, constructing a concrete damp-proof layer; Step 10, constructing a retaining wall; Step 11, pouring the filling layer; Step 12, sealing the insulation layer, waterproofing layer, and the openings in the zero-floor slab. This invention solves the technical problems of traditional backfilling methods, such as long construction cycles and insufficient backfill quality when manual backfilling is used if the space is insufficient for mechanical work.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and specifically relates to a building core backfill structure and its construction method where the zero-floor slab is constructed first. Background Technology

[0002] During the construction of a certain project, due to external factors, it was necessary to first seal the basement roof before backfilling. Traditional backfilling methods typically involve backfilling first, followed by construction of the basement roof slab. This approach is unsuitable for the time constraints of this application. If mechanical backfilling is performed after the basement roof slab is constructed, insufficient space for the machinery becomes available when the soil reaches a depth of 2 meters from the bottom of the slab, making mechanical construction impossible. If manual compaction continues, difficulties arise when the soil is close to the bottom of the slab, resulting in substandard backfill quality and excessive subsidence of the surrounding road surface. Summary of the Invention

[0003] The purpose of this invention is to provide a backfill structure for the building core where the ground floor slab is constructed first, and its construction method. This invention aims to solve the technical problems of long construction periods in traditional backfilling methods and the inability to meet backfilling quality requirements when manual backfilling is used when the remaining space below the basement roof slab does not meet the working space requirements of construction machinery if the scheme of sealing the roof first is adopted.

[0004] To achieve the above objectives, the present invention adopts the following technical solution.

[0005] A building core backfill structure constructed first on the ground floor slab, located below the ground floor slab; includes a raft foundation, side columns, retaining walls, a lower backfill layer, an upper backfill layer, and a filling layer;

[0006] The zero-level slab has spaced-apart openings for people to enter; horizontal and vertical beams are installed at the bottom of the zero-level slab; the raft foundation is poured at the bottom of the foundation pit; there is a set of side columns, spaced along the four edges of the raft foundation, with the bottom of the side columns supported on the raft foundation and the top of the side columns supported on the bottom of the horizontal or vertical beams; a gap is left between the side columns and the edge of the raft foundation; the lower backfill layer is laid on the raft foundation, and the top surface of the lower backfill layer is flush with the zero-level slab. The spacing between the upper and lower backfill layers is not less than 2m; the upper backfill layer is laid on top of the lower backfill layer, and the spacing between the upper backfill layer and the zero-layer slab is not less than 1.3m; a trench is provided in the upper backfill layer; a sand layer is provided at the bottom of the trench; a geotextile layer is laid on top of the sand layer, and both ends of the geotextile layer extend beyond the top of the trench; a permeable pipe is provided above the geotextile layer and along the long axis of the trench; one end of the permeable pipe is connected to a sewage well, and the other end of the permeable pipe... One end is sealed with a pipe cap; holes are arranged in a quincunx pattern on the wall of the seepage pipe; a layer of crushed stone is laid between the seepage pipe and the geotextile layer; the portion of the geotextile layer extending beyond the top of the trench is laid on top of the crushed stone layer; a concrete moisture barrier is installed on top of the upper backfill layer; a permeable drain is installed on the concrete moisture barrier above the seepage pipe, with the lower section of the permeable drain extending into the trench; the top of the concrete moisture barrier, located above the seepage pipe... A retaining wall is provided between each adjacent side column; the top of the retaining wall is connected to a horizontal beam or a vertical beam; structural columns are provided at intervals in the retaining wall; the bottom of the zero-layer slab, in the space enclosed by the horizontal beam and the vertical beam, is filled with an insulation layer; the bottom surface of the insulation layer is flush with the bottom surface of the horizontal beam and the vertical beam; a waterproof layer is fully applied to the bottom of the insulation layer, the horizontal beam, and the vertical beam; the filling layer is made of lightweight aggregate concrete and is filled between the concrete moisture-proof layer and the waterproof layer on the inner side of the retaining wall.

[0007] Preferably, the crossbeams and longitudinal beams form a rectangular grid structure at the bottom of the zero-layer slab; the openings are made on the zero-layer slab at the position of each rectangular grid cell in the rectangular grid structure, and the diameter of the openings is 0.5m to 1m.

[0008] Preferably, a central column is arranged at intervals in the space between the bottom of the zero-layer slab and the inner side of a group of side columns; the bottom of the central column is supported on the raft foundation, and the top of the central column is supported on the bottom of the horizontal or vertical beam; both the central column and the side columns are provided with independent column bases at their bottoms.

[0009] Preferably, a thickened layer is provided at the bottom of the raft foundation and at the location of the corresponding independent column foundation; the horizontal cross-section of the thickened layer is rectangular, and the side dimensions of the rectangle gradually decrease from top to bottom; the four sides of the thickened layer form an angle of 45° with the horizontal plane; and a concrete pad layer is provided at the bottom of the raft foundation.

[0010] Preferably, the distance between the side column and the edge of the raft foundation is 1.8m to 2.2m.

[0011] Preferably, the retaining wall is constructed of bricks, and toothed joints are provided on the side where the structural column connects to the retaining wall; tie bars are provided between the structural column and the retaining walls on both sides.

[0012] Preferably, the permeation pipe is composed of a group of pipe segments spliced ​​together, and the joint width between adjacent pipe segments is no more than 2mm; the two ends of the geotextile layer are overlapped and connected on the top of the crushed stone layer, and the width of the overlap is no less than 500mm.

[0013] Preferably, the top surface of the concrete moisture-proof layer on both sides of the trench is provided with a slope of 1%, and the bottom edge of the slope is located at the trench.

[0014] Preferably, the seepage pipe has a slope of 0.5%, with the bottom of the slope facing the sewage well.

[0015] A construction method for a building core backfill structure where the zero-floor slab is constructed first includes the following steps.

[0016] Step 1: Construct the raft foundation and side columns.

[0017] Step 2: Construct a zero-floor slab at the top of the side column; when constructing the zero-floor slab, reserve an opening for the following people in the zero-floor slab.

[0018] Step 3: Install the insulation and waterproofing layers at the bottom of the zero-layer slab, and make openings in the insulation and waterproofing layers at the corresponding opening positions.

[0019] Step 4: Construct a new construction access road; the construction access road connects the space below the ground floor slab with the road on one side of the building.

[0020] Step 5: Use mechanical construction to backfill the soil layer; the backfilling process is carried out step by step from the center outwards.

[0021] Step Six: When the remaining space is insufficient for mechanical operation, the backfill soil layer is filled manually.

[0022] Step 7: Excavate a trench in the upper backfill layer, and then lay a sand layer and a geotextile layer at the bottom of the trench.

[0023] Step 8: Place the drainage pipe in the trench and fill the area around the drainage pipe with a layer of gravel.

[0024] Step 9: Constructing the concrete damp-proof layer: Pour a concrete damp-proof layer on top of the backfill layer.

[0025] Step 10: Construct the retaining wall.

[0026] Step 11: Pour a filling layer into the space between the concrete moisture-proof layer and the waterproof layer through the opening until the top surface of the filling layer is flush with the bottom surface of the waterproof layer.

[0027] Step 12: Seal the openings in the insulation layer, waterproof layer, and bottom slab. Construction is now complete.

[0028] Compared with the prior art, the present invention has the following features and beneficial effects.

[0029] 1. This invention is applicable to structures with foundations below ±0 requiring backfilling and ground floor structures requiring waterproofing, insulation, and a short construction period. The structure and construction method of this invention are advantageous for main structures with short construction periods. This invention allows the construction of the ground floor beams and slabs (i.e., zero-floor slabs) above the foundation to be carried out before backfilling, with a pre-reserved access point on the zero-floor slab. Then, the construction of the main structure above the basement can be carried out, allowing the foundation backfilling and the main structure above the basement to be carried out simultaneously. Compared with the traditional process of backfilling first and then constructing the main structure, this greatly shortens the construction cycle.

[0030] 2. The backfill structure of the building core of the present invention includes a raft foundation, side columns, central columns, and retaining walls. A retaining wall is set around the building core backfill structure to effectively isolate the building core from the external road, providing a barrier structure for the external road and avoiding the technical problem of excessive subsidence of the surrounding road surface due to the backfill quality not meeting the predetermined requirements. At the same time, crossbeams and longitudinal beams are set at the bottom of the zero-layer slab, and a filling layer is poured between the zero-layer slab and the concrete moisture-proof layer, which solves the technical problem that the backfill quality of traditional backfill structures cannot meet the requirements.

[0031] 3. The backfill structure and construction method of the present invention are particularly suitable for structures with abundant groundwater and where precipitation around the structure may erode the foundation. The waterproof layer of this application can prevent the moisture of the underground soil from entering the structure. Rainwater and surface water around the structure can be discharged into the municipal pipe network through seepage pipes, which is beneficial to the safety and service life of the structure. Similarly, the internal filling can prevent the soil around the structure from entering the foundation backfill area below the structure, thereby preventing the ground around the structure from settling.

[0032] 4. To prevent water accumulation under the roof slab and ground dampness, this invention includes a permeable drainage pipe and a concrete damp-proof layer. The water accumulated under the waterproof layer is drained through the permeable drainage pipe. At the same time, a waterproof layer is fully applied to the bottom of the insulation layer, crossbeams, and longitudinal beams. The multi-layer waterproof structure effectively prevents ground dampness. Attached Figure Description

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] Figure 1This is a schematic diagram of the vertical cross-sectional structure of the atrial core backfill structure of the present invention.

[0035] Figure 2 This is a schematic diagram of the elevation structure of the connection between the retaining wall and the structural column in this invention.

[0036] Figure 3 This is a schematic diagram of the planar structure connecting the retaining wall and the structural column in this invention.

[0037] Figure 4 This is a diagram showing the arrangement of the central column and the side columns in this invention.

[0038] Figure 5 This is a schematic diagram of the structure inside the trench in this invention.

[0039] Figure 6 This is a schematic diagram of the structure in this invention where a thickened layer is provided at the bottom of the raft foundation.

[0040] Attached diagram labels: 1 - Zero-layer slab, 2 - Raft foundation, 3 - Side column, 4 - Retaining wall, 5 - Lower backfill layer, 6 - Upper backfill layer, 7 - Filling layer, 8 - Horizontal beam, 9 - Longitudinal beam, 10 - Trench, 11 - Sand layer, 12 - Geotextile layer, 13 - Crushed stone layer, 14 - Drainage pipe, 15 - Concrete damp-proof layer, 16 - Structural column, 17 - Insulation layer, 18 - Waterproof layer, 19 - Central column, 20 - Independent column base, 21 - Thickened layer, 22 - Concrete cushion layer, 23 - Toothed joint, 24 - Tie bar, 25 - Permeable floor drain. Implementation

[0041] like Figure 1-6 As shown, this building structure, which is constructed with the zero-floor slab first and then backfilled, is located below the zero-floor slab 1; it includes a raft foundation 2, side columns 3, retaining walls 4, a lower backfill layer 5, an upper backfill layer 6, and a filling layer 7.

[0042] The zero-level slab 1 has spaced-apart openings for people to enter; a horizontal beam 8 and a longitudinal beam 9 are provided at the bottom of the zero-level slab 1; the raft foundation 2 is poured at the bottom of the foundation pit; there is a set of side columns 3, spaced along the four edges of the raft foundation 2, with the bottom of the side columns 3 supported on the raft foundation 2 and the top of the side columns 3 supported on the bottom of the horizontal beam 8 or the longitudinal beam 9; a gap is left between the side columns 3 and the edge of the raft foundation 2; the lower backfill layer 5 is laid on the raft foundation 2, and the distance between the top surface of the lower backfill layer 5 and the zero-level slab 1 is not less than 2m; the upper backfill layer 5 is laid on the raft foundation 2; a horizontal beam 8 and a longitudinal beam 9 are provided at the bottom of the foundation pit; the upper backfill layer 2 is laid on the bottom of the foundation pit; the lower backfill layer 5 ... A backfill layer 6 is laid on top of the lower backfill layer 5, and the distance between the upper backfill layer 6 and the zero-layer slab 1 is not less than 1.3m; a trench 10 is provided in the upper backfill layer 6; a sand layer 11 is provided at the bottom of the trench 10; a geotextile layer 12 is laid on top of the sand layer 11, and both ends of the geotextile layer 12 extend beyond the top of the trench 10; a permeable pipe 14 is provided above the geotextile layer 12 and along the longitudinal axis of the trench 10; one end of the permeable pipe 14 is connected to a sewage well, and the other end of the permeable pipe 14 is sealed with a pipe cap; in the permeable... The pipe wall of pipe 14 is perforated in a quincunx pattern, with each perforation being 5mm in diameter and 100mm apart. A layer of crushed stone 13 is laid between the perforation pipe 14 and the geotextile layer 12. The portion of the geotextile layer 12 extending beyond the top of the trench 10 is laid on top of the crushed stone layer 13. A concrete moisture barrier 15 is installed on top of the upper backfill layer 6. A permeable drain 25 is installed on the concrete moisture barrier 15, above the perforation pipe 14, with its lower section extending to the trench 10. The top of the concrete moisture barrier 15... A retaining wall 4 is provided between each adjacent side column 3; the top of the retaining wall 4 is connected to the horizontal beam 8 or the longitudinal beam 9; structural columns 16 are provided at intervals in the retaining wall 4; the bottom of the zero layer slab 1, in the space enclosed by the horizontal beam 8 and the longitudinal beam 9, is filled with an insulation layer 17; the bottom surface of the insulation layer 17 is flush with the bottom surface of the horizontal beam 8 and the longitudinal beam 9; a waterproof layer 18 is fully attached to the bottom of the insulation layer 17, the horizontal beam 8, and the longitudinal beam 9; the filling layer 7 is made of lightweight aggregate concrete and is filled between the concrete moisture-proof layer 15 and the waterproof layer 18 on the inner side of the retaining wall 4.

[0043] In this embodiment, the crossbeam 8 and the longitudinal beam 9 form a rectangular grid structure at the bottom of the zero layer plate 1; the opening is opened on the zero layer plate 1 at the position of each rectangular grid cell in the rectangular grid structure, and the diameter of the opening is 0.5m to 1m.

[0044] In this embodiment, a central column 19 is arranged at intervals in the space between the bottom of the zero-layer slab 1 and the inner side of a group of side columns 3; the bottom of the central column 19 is supported on the raft foundation 2, and the top of the central column 19 is supported on the bottom of the horizontal beam 8 or the longitudinal beam 9; the bottom of the central column 19 and the side columns 3 are both provided with independent column bases 20.

[0045] In this embodiment, a thickened layer 21 is provided at the bottom of the raft foundation 2 and at the position of the corresponding independent column base 20; the horizontal cross-section of the thickened layer 21 is rectangular, and the side dimension of the rectangle gradually decreases from top to bottom; the four sides of the thickened layer 21 are at an angle of 45° with the horizontal plane; a concrete pad layer 22 is provided at the bottom of the raft foundation 2.

[0046] In this embodiment, the distance between the side column 3 and the edge of the raft foundation 2 is 1.8m to 2.2m.

[0047] In this embodiment, the retaining wall 4 is constructed of bricks, and toothed joints 23 are provided on the side where the structural column 16 is connected to the retaining wall 4; tie bars 24 are provided between the structural column 16 and the retaining walls 4 on both sides; and a C20 concrete layer is provided at the bottom of the structural column 16.

[0048] In this embodiment, the seepage pipe 14 is a set of pipe segments spliced ​​together, and the joint width between adjacent pipe segments is no more than 2mm; the two ends of the geotextile layer 12 are overlapped and connected on the top of the crushed stone layer 13, and the width of the overlap is no less than 500mm.

[0049] In this embodiment, the top surface of the concrete moisture-proof layer 15 on both sides of the trench 10 is respectively provided with a slope of 1%, and the bottom edge of the slope is located at the trench 10; so that the water accumulated on the concrete moisture-proof layer 15 can flow into the trench 10 through the permeable floor drain 25.

[0050] In this embodiment, the seepage pipe 14 is provided with a slope of 0.5%, with the bottom of the slope facing the sewage well.

[0051] In this embodiment, the tie bar 24 horizontally penetrates the structural column 16, and both ends of the tie bar 24 are respectively embedded in the retaining walls 4 on both sides of the structural column 16; the anchorage length of the tie bar 24 in each retaining wall 4 is not less than 500mm.

[0052] In this embodiment, the trench 10 has a set of longitudinal trenches and a transverse trench; the transverse trench 10 is set along the inner edge of the raft foundation 2; a main seepage pipe is set in the transverse trench 10, and a branch seepage pipe is set in the set of longitudinal trenches 10; one end of the main seepage pipe is sealed, and the other end of the main seepage pipe is connected to the sewage well.

[0053] In this embodiment, there are at least two geotextile layers 12 in the trench 10, and the long axis of adjacent geotextile layers 12 in the trench 10 is overlapped, with the overlap length being at least 500mm.

[0054] In this embodiment, the bottom of the retaining wall 4 is provided with an enlarged foot 24.

[0055] The construction method for this type of building with a zero-floor slab first and a backfilled core structure includes the following steps.

[0056] Step 1: Construct the raft foundation 2 and the side columns 3.

[0057] Step 2: Construct the zero-layer slab 1 on the top of the side column 3; when constructing the zero-layer slab 1, reserve an opening for the following people on the zero-layer slab 1.

[0058] Step 3: Construct insulation layer 17 and waterproof layer 18 at the bottom of the zero layer 1, and make openings in insulation layer 17 and waterproof layer 18 at the positions corresponding to the openings.

[0059] Step 4: Construct a new construction access road; the construction access road connects the space below the zero-floor slab 1 with the road on one side of the building.

[0060] Step 5: Use mechanical construction to backfill layer 5; the construction of backfill layer 5 is carried out step by step from the center to the periphery; the backfill layer 5 is spread and compacted in layers, each layer is 350mm, and compacted 3 to 4 times;

[0061] Step 6: When the remaining space does not meet the mechanical working requirements, i.e., less than 2.0m, the backfill soil layer 6 is filled manually; for every 200mm layer, it is compacted 3-4 times with a frog-type rammer.

[0062] Step 7: Excavate trench 10 in the backfill layer 6, and then lay a sand layer 11 and a geotextile layer 12 at the bottom of trench 10; excavate trench 10 manually with dimensions of 300*400 mm, ensuring the sidewalls of trench 10 are vertical. Sand layer 11 uses medium sand; the medium sand is laid manually to a thickness of 100 mm, initially leveled with a shovel, and then compacted with a frog-type rammer. Determine the geotextile size based on the dimensions of trench 10 and the overlap length, and then cut the geotextile to a flat surface with a longitudinal overlap length ≥ 500 mm; leave both ends of the geotextile open, and after the gravel is laid, close and overlap the ends of the geotextile, ensuring the overlap length is > 500 mm.

[0063] Step 8: Place the seepage pipe 14 in the trench 10 and fill the area around the seepage pipe 14 with a layer of crushed stone 13; the thickness of the crushed stone layer 13 is 100mm, the particle size of the crushed stone is 20~30mm, the porosity is not less than 30%, and the crushed stone is required to be clean and the surface of the crushed stone is flat.

[0064] Step 9: Constructing the concrete damp-proof layer 15: Pour the concrete damp-proof layer 15 on top of the backfill layer 6.

[0065] Step 10: Construct retaining wall 4; retaining wall 4 is constructed using MU5 mortar + 240mm × 115mm × 53mm MU15 lime-sand bricks.

[0066] Step 11: Pour the filling layer 7 into the space between the concrete moisture-proof layer 15 and the waterproof layer 18 through the opening until the top surface of the filling layer 7 is flush with the bottom surface of the waterproof layer 18.

[0067] Step 12: Seal the openings in the insulation layer 17, waterproof layer 18, and zero-layer board 1. The construction is now complete.

[0068] In this embodiment, before backfilling, the garbage and other debris at the bottom of the foundation should be cleaned up. The soil material should be the original soil excavated from the foundation pit, and organic impurities and particles with a diameter greater than 50mm should be removed. The moisture content should meet the requirements.

[0069] In this embodiment, steps five and six should be performed before backfilling to check whether the soil material and moisture content are within the control range. The on-site moisture content should be controlled between 17% and 19%, generally considered suitable when it can be formed into a ball by hand and crumbles upon falling; the optimal moisture content is 18%. If the moisture content is too high, measures such as loosening, drying, air drying, replacing the soil for backfilling, or mixing in dry soil or other absorbent materials should be taken to prevent the formation of "rubber soil." If the soil material is too dry, it should be pre-wetted with water, the number of compaction passes should be increased, or a higher-powered compaction machine should be used.

[0070] In this embodiment, the specific construction method for backfilling layer 5 using mechanical construction in step five is as follows: A bulldozer is used for backfilling, laying the soil in layers from bottom to top. Large-slope bulldozing is prohibited; pushing instead of compaction, without layering, and in one-time filling are not allowed. The bulldozer transports the backfill soil, which can be piled up and transported in one go to reduce soil loss. The backfilling procedure adopts a longitudinal laying sequence, using a road roller for compaction, employing a "thin fill, slow drive, multiple passes" method. The compaction direction gradually moves from both sides towards the middle, with each roller overlapping approximately 15-25cm. Areas where slopes and corners cannot be compacted should be manually tamped or compacted using small tamping equipment. When compacting backfill at walls, columns, and foundations, the distance between the road roller and the wall / column should not be less than 0.5m. After each layer is compacted, a bulldozer is used to roughen the surface to facilitate bonding.

[0071] In this embodiment, before tamping in step six, the fill soil should be initially leveled. Tamping should be carried out in a certain direction, with one tamping pass over another, tamping rows connected, and tamping in two crisscrossing directions, in layers. When using small machinery such as a frog-type tamping machine, the fill soil should be initially leveled before tamping. The tamping machine should then tamp the soil sequentially, evenly, without leaving any gaps.

[0072] In this embodiment, if the lower backfill layer 5 that has been filled is flooded, the mud should be removed before the upper backfill layer 6 can be constructed; the filling area should maintain a certain slope, or be slightly higher in the middle and slightly lower on both sides, to facilitate drainage; the filling should be compacted on the same day.

[0073] In this embodiment, during winter filling, ice, snow, and insulation materials on the foundation should be removed, accumulated water should be drained, and ice and silt should be excavated. For foundation pit filling, frozen soil blocks or frozen clay should not be used as soil material. Filling should be carried out continuously, with each layer compacted to prevent the foundation or the already filled soil from freezing. When the average temperature is below -5℃, the thickness of each layer of soil should be reduced by 20% to 50% compared to construction at normal temperature, and each layer should be compacted. The height of winter filling should be increased by 1.5% to 3.0% to allow for a settling.

Claims

1. A backfill structure for the building core, constructed before the ground floor slab, located below the ground floor slab (1); characterized in that: It includes a raft foundation (2), side columns (3), lower backfill layer (5), upper backfill layer (6) and filling layer (7); The zero-layer slab (1) has openings spaced apart for people to enter; a horizontal beam (8) and a longitudinal beam (9) are provided at the bottom of the zero-layer slab (1); the raft foundation (2) is poured at the bottom of the foundation pit; there is a set of side columns (3) spaced apart along the four edges of the raft foundation (2), and the bottom of the side columns (3) is supported on the raft foundation (2), and the top of the side columns (3) is supported on the bottom of the horizontal beam (8) or the longitudinal beam (9); there is a gap between the side columns (3) and the edge of the raft foundation (2); the lower backfill layer (5) is laid on the raft foundation (2), and the gap between the top surface of the lower backfill layer (5) and the zero-layer slab (1) is not small. The upper backfill layer (6) is laid on top of the lower backfill layer (5), and the distance between the upper backfill layer (6) and the zero layer slab (1) is not less than 1.3m; a trench (10) is provided in the upper backfill layer (6); a sand layer (11) is provided at the bottom of the trench (10); a geotextile layer (12) is laid on top of the sand layer (11), and both ends of the geotextile layer (12) extend beyond the top of the trench (10); a seepage pipe (14) is provided above the geotextile layer (12) and along the long axis of the trench (10); the seepage pipe (14) is connected to the sewage well, and the other end of the seepage pipe is sealed with a special pipe cap. The drainage pipe (14) is sealed; holes are arranged in a quincunx pattern on the pipe wall; a gravel layer (13) is laid between the drainage pipe (14) and the geotextile layer (12); the portion of the geotextile layer (12) extending beyond the top of the trench (10) is laid on top of the gravel layer (13); a concrete moisture barrier layer (15) is set on top of the upper backfill layer (6); a permeable drain (25) is set on the concrete moisture barrier layer (15) above the drainage pipe (14), and the lower section of the permeable drain (25) extends to the trench (10); the top of the concrete moisture barrier layer (15) is located between each adjacent side column (3). A retaining wall (4) is provided; the top of the retaining wall (4) is connected to the cross beam (8) or the longitudinal beam (9); structural columns (16) are provided at intervals in the retaining wall (4); the bottom of the zero layer board (1) is filled with an insulation layer (17) in the space enclosed by the cross beam (8) and the longitudinal beam (9); the bottom surface of the insulation layer (17) is flush with the bottom surface of the cross beam (8) and the longitudinal beam (9); a waterproof layer (18) is fully attached to the bottom of the insulation layer (17), the cross beam (8), and the longitudinal beam (9); the filling layer (7) is made of lightweight aggregate concrete and is filled between the concrete moisture-proof layer (15) and the waterproof layer (18) on the inner side of the retaining wall (4).

2. The building core backfill structure constructed with the first floor slab as described in claim 1, characterized in that: The crossbeam (8) and longitudinal beam (9) form a rectangular grid structure at the bottom of the zero layer plate (1); the opening is opened on the zero layer plate (1) at the position of each rectangular grid in the rectangular grid structure, and the diameter of the opening is 0.5m~1m.

3. The building core backfill structure constructed first with the ground floor slab as described in claim 1, characterized in that: At the bottom of the zero-layer slab (1), a central column (19) is arranged at intervals in the space inside a set of side columns (3); the bottom of the central column (19) is supported on the raft foundation (2), and the top of the central column (19) is supported on the bottom of the cross beam (8) or the longitudinal beam (9); both the central column (19) and the side columns (3) are provided with independent column bases (20).

4. The building core backfill structure constructed first with the ground floor slab as described in claim 3, characterized in that: A thickened layer (21) is provided at the bottom of the raft foundation (2) and at the position of the corresponding independent column base (20); the horizontal cross-section of the thickened layer (21) is rectangular, and the side dimension of the rectangle gradually decreases from top to bottom; the four sides of the thickened layer (21) are at an angle of 45° with the horizontal plane; a concrete pad layer (22) is provided at the bottom of the raft foundation (2).

5. The building core backfill structure constructed with the first floor slab as described in claim 1, characterized in that: The distance between the edge column (3) and the edge of the raft foundation (2) is 1.8m to 2.2m.

6. The building core backfill structure constructed first with the ground floor slab as described in claim 1, characterized in that: The retaining wall (4) is constructed of bricks, and toothed joints (23) are provided on the side where the structural column (16) connects to the retaining wall (4); tie bars (24) are provided between the structural column (16) and the retaining walls (4) on both sides.

7. The building core backfill structure constructed with the first floor slab as described in claim 1, characterized in that: The seepage pipe (14) is a set of pipe segments spliced ​​together, and the joint width between adjacent pipe segments is no more than 2mm; the two ends of the geotextile layer (12) are connected to the top of the crushed stone layer (13), and the width of the overlap is no less than 500mm.

8. The building core backfill structure constructed first with the ground floor slab as described in claim 1, characterized in that: The top surface of the concrete moisture-proof layer (15) on both sides of the trench (10) is provided with a slope of 1%, and the bottom edge of the slope is located at the trench (10).

9. The building core backfill structure constructed first with the ground floor slab as described in claim 1, characterized in that: The seepage pipe (14) is provided with a slope of 0.5%, with the bottom of the slope facing the sewage well.

10. A construction method for a building core backfill structure constructed first, as described in any one of claims 1-9, characterized in that, The steps include the following: Step 1: Construct the raft foundation (2) and side columns (3); Step 2: Construct a zero-floor slab (1) on the top of the side column (3); when constructing the zero-floor slab (1), reserve an opening for the following people on the zero-floor slab (1); Step 3: Construct an insulation layer (17) and a waterproof layer (18) at the bottom of the zero layer board (1), and make openings at the corresponding opening positions on the insulation layer (17) and the waterproof layer (18); Step 4: Construct a new construction access road; the construction access road connects the space below the zero-floor slab (1) with the road on one side of the building; Step 5: Use mechanical construction to backfill the soil layer (5); the backfilling of the soil layer (5) is carried out step by step from the center to the surrounding area; Step 6: When the remaining space does not meet the mechanical work requirements, the backfill soil layer is filled manually (6); Step 7: Excavate a trench (10) in the upper backfill layer (6), and then lay a sand layer (11) and a geotextile layer (12) at the bottom of the trench (10). Step 8: Place the seepage pipe (14) in the trench (10) and fill the area around the seepage pipe (14) with a layer of gravel (13). Step 9: Constructing the concrete damp-proof layer (15): Pour the concrete damp-proof layer (15) on top of the upper backfill layer (6); Step 10: Construct the retaining wall (4); Step 11: Pour a filling layer (7) into the space between the concrete damp-proof layer (15) and the waterproof layer (18) through the opening until the top surface of the filling layer (7) is flush with the bottom surface of the waterproof layer (18); Step 12: Seal the openings in the insulation layer (17), waterproof layer (18), and zero layer board (1). The construction is now complete.

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