Underground garage high-low span part backfill construction method
By using liquid fly ash backfill and a stepped structure design, the problems of construction stability and efficiency in the high and low span sections of the underground parking garage were solved, achieving a highly efficient and environmentally friendly backfilling effect that meets construction specifications and safety requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-21
- Publication Date
- 2026-03-10
AI Technical Summary
In existing construction methods, the backfilling of lime-soil at the high and low spans of underground parking garages is unstable, posing a risk of settlement, resulting in low construction efficiency and difficulty in meeting the quality requirements of the backfill soil, thus posing potential quality hazards.
Liquid fly ash was used for backfilling, combined with the pouring of the first raft slab and the trimming of the slope to form a stepped structure. The structure was then poured and vibrated in layers until it was level, followed by the pouring of the second raft slab and the placement of post-pouring strips to ensure structural stability and density.
It improves the stability and density of the backfill structure, reduces the risk of settlement, shortens the construction period, improves construction efficiency, is environmentally friendly and energy-saving, meets the load-bearing requirements, and avoids voids and cracks.
Smart Images
Figure CN121629948A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of building construction, in particular to a backfill construction method for high-low span parts of an underground garage. BACKGROUND
[0002] In building engineering, residential engineering underground garage usually involves civil air defense engineering, and the civil air defense engineering is separately arranged at the negative two layer, which has stronger anti-blast and anti-impact capability. The negative two layer is deeper than the negative one layer, and has double buffering of the negative one layer structure and soil layer in the upper part, which can better resist the shock wave and vibration of nuclear weapons and conventional weapons, has higher protection efficiency, and is easier to achieve chemical protection and sealing. The probability of deep underground space being polluted by the outside world is lower, and it is easier to meet the isolation requirements of civil air defense engineering to toxic agents and biological war agents through the design of air-tight doors, ventilation systems, etc. In such projects, the area of the negative two layer civil air defense engineering is usually smaller than that of the negative one layer garage. When the negative one layer underground garage is poured, the negative two layer top plate serves as the foundation of the negative one layer, and there is a high-low span part between the negative two layer top plate and the foundation pit. Therefore, after the construction of the negative two layer civil air defense engineering is completed, the high-low span part usually needs to be backfilled.
[0003] In the existing construction method, the soil backfill is usually used. When the underground water level is high, the soil backfill structure is not stable enough and has a high risk of settlement. Moreover, the high-low span part usually cannot reserve enough construction surface, so that the soil backfill construction operation surface is narrow, vehicles and machinery cannot enter, and a tower crane needs to be used for hoisting, which reduces the construction efficiency and increases the construction period, affecting the construction efficiency of the surrounding main body. When the backfilled soil is compacted, only small air rammers can be used for compaction, so the quality of the backfilled soil cannot be guaranteed. Secondly, the post-cast strip of the backfill structure cannot be left on the wall side according to the specification, but should be left in the area with smaller structural stress, such as the middle 1 / 3 of the beam or slab span. When the backfilled soil is manually backfilled under the plate, the space height is limited, and the backfilled soil construction cannot meet the requirement of a higher compaction coefficient. There is a suspended phenomenon under the beam or slab span, which causes great quality hidden dangers. SUMMARY
[0004] The purpose of the present application is to provide a backfill construction method for high-low span parts of an underground garage to solve the technical defects in the existing backfill construction method.
[0005] To achieve this purpose, the following technical solutions are used in the present application: The backfill construction method for high-low span parts of an underground garage is used for backfilling the high-low span part between the negative two layer top plate and the foundation pit, wherein the backfill construction method for high-low span parts of an underground garage comprises the following steps: S1, pouring a first raft, the first raft, the negative two layer wall and the negative two layer top plate are poured at one time, the upper end surface of the first raft is flush with the upper end surface of the negative two layer top plate, and the overhanging length of the first raft in the horizontal direction is one third of the horizontal distance between the negative two layer wall and the foundation pit; S2, after the concrete strength of the first raft, the negative two layer wall and the negative two layer roof meet the design requirements, waterproof construction is carried out on the first raft and the negative two layer wall; S3, the original 1:1 natural slope structure of the slope is modified to a stepped structure; S4, liquid fly ash is backfilled between the negative two layer wall and the slope, and the liquid fly ash is backfilled by layer pouring and vibration into place, the backfill height of the liquid fly ash is flush with the bottom of the first raft, and surface curing is carried out after backfilling is completed; S5, a second raft is poured on the backfilled liquid fly ash, the upper end surface of the second raft is flush with the upper end surface of the first raft, and a post-poured strip is left between the second raft and the first raft; S6, after the concrete strength of the second raft meets the design requirements, the post-poured strip is poured.
[0006] Optionally, in the step S1, a plurality of air vents are left on the first raft, each air vent penetrates the first raft in the vertical direction, and a water stop steel plate is arranged in the hole wall of each air vent.
[0007] Optionally, in the step S4, when the liquid fly ash is poured below the first raft, the liquid fly ash is vibrated through the plurality of air vents to increase the slump of the liquid fly ash.
[0008] Optionally, in the step S6, the post-poured strip is poured at the same time as the plurality of air vents.
[0009] Optionally, in the step S1, the air vent is a square hole with a side length of 150 mm, and the spacing between two adjacent air vents is 5 m.
[0010] Optionally, in the step S2, when the first raft and the negative two layer wall are waterproofed, the waterproof coiled material is continuously laid on the bottom of the first raft and the side of the negative two layer wall close to the foundation pit.
[0011] Optionally, in the step S1, the first raft is provided with a steel bar at one end away from the negative two layer wall in the horizontal direction, the lower part of the steel bar is laid with the waterproof coiled material, and the steel bar and the waterproof coiled material are fixed by turning up before the liquid fly ash is backfilled in the step S4.
[0012] Optionally, the angle between the steel bar and the waterproof coiled material after being fixed by turning up and the horizontal plane is 30° to 90°.
[0013] Optionally, in the step S4, the liquid fly ash comprises fly ash particles, cement and admixtures.
[0014] Optionally, in the step S1, a scaffold is arranged at the bottom to support during pouring of the first raft.
[0015] Advantages of the present application: The present application provides a backfill construction method for high-low span parts of an underground garage, which is used for backfilling high-low span parts between a negative second floor top plate and a foundation pit. Pouring a first raft provides a structural foundation for a post-pouring strip left by the backfill construction method for high-low span parts of an underground garage, and meets the construction specification. Waterproof construction is performed on the first raft bottom and the earth-facing surface of the negative second floor wall, which can effectively prevent leakage of the negative second floor civil air defense project of the underground garage. By trimming the revetment, the bearing capacity of the revetment can be enhanced, thereby enhancing the stability of the backfill structure of the high-low span parts of the underground garage and reducing the risk of settlement in the later period. By replacing the original ash-soil backfill with liquid fly ash backfill, the following advantages are achieved: the liquid fly ash has high fluidity and can be filled into the corners and gaps between the negative second floor wall and the revetment by relying on its own gravity without the need for air ramming, thereby avoiding the hollow or overhead problems that may occur in traditional backfilling and ensuring the compactness of the backfilling; the liquid fly ash has low shrinkage, and the fly ash particle size is reasonable. When used with admixtures, the volume shrinkage rate after hardening is much lower than that of plain soil or gravel, which can reduce the cracking of the backfill layer, avoid later ground settlement, and reduce the risk of rework caused by high underground water level; the liquid fly ash uses industrial waste fly ash as the main raw material, which realizes the transformation of waste into treasure, is environmentally friendly and energy-saving without pollution, meets the requirements of green construction and civilized construction, improves the on-site construction image and safety factor; the strength of the liquid fly ash is controllable, and by adjusting the cement content or the type of admixtures, the strength after hardening can be controlled between 1.2 MPa and 3 MPa, which can meet the bearing capacity requirements of the backfill of the high-low span parts of the underground garage and will not affect the subsequent foundation construction due to high strength. Compared with the ash-soil backfilling that requires the use of a tower crane for hoisting, the liquid fly ash backfilling through a pump truck is more convenient, greatly reduces the construction period, improves the construction efficiency, and reduces the labor and mechanical costs. The post-pouring strip can effectively avoid the cracking of the raft caused by shrinkage stress during the hardening process of the second raft and the first raft, and improve the structural strength of the raft. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 is a method flow chart of the backfill construction method for high-low span parts of an underground garage according to the embodiment of the present application; Figure 2 is a backfill construction schematic diagram of the step S1 of the underground garage high-low span part backfill construction method according to the embodiment of the present application; Figure 3Is the step S2 and S3 of the embodiment of the application corresponding underground garage high low span backfill construction schematic diagram of part; Figure 4 Is the step S4 of the embodiment of the application corresponding underground garage high low span backfill construction schematic diagram of part; Figure 5 Is the step S5 of the embodiment of the application corresponding underground garage high low span backfill construction schematic diagram of part; Figure 6 Is the structure schematic diagram of the air hole of the embodiment of the application.
[0017] In the figure: 1, the first raft; 11, the air hole; 12, the water stop steel plate; 13, the steel bar; 2, the negative two layer wall; 3, the negative two layer roof; 4, the revetment; 5, the liquid fly ash; 6, the second raft; 7, the post-cast strip; 8, the waterproof roll material; 9, the scaffold. DETAILED DESCRIPTION
[0018] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar parts or parts having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.
[0019] In the description of the present application, unless explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, can be detachably connected, can be mechanically connected, can be electrically connected, can be directly connected, can be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0020] In the description of the present application, unless explicitly specified and limited, the first feature "on" or "below" the second feature can include that the first feature and the second feature are in direct contact, or that the first feature and the second feature are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.
[0021] The technical solutions of the present application are further illustrated below by specific embodiments in conjunction with the accompanying drawings.
[0022] like Figures 1 to 6 As shown, this invention provides a backfilling construction method for the high-low span section of an underground parking garage, used for backfilling the high-low span section between the top slab of the second basement level and the foundation pit. The backfilling construction method for the high-low span section of an underground parking garage includes the following steps: S1. Cast the first raft slab 1. The first raft slab 1, the second basement wall 2, and the second basement roof slab 3 are cast in one go. The upper surface of the first raft slab 1 is flush with the upper surface of the second basement roof slab 3. The horizontal cantilever length L of the first raft slab 1 is one-third of the horizontal distance D between the second basement wall 2 and the foundation pit. Specifically, according to the construction specifications, the post-cast strip 7 should be placed in an area with relatively low structural stress, such as one-third of the span of a beam or slab. Figure 2 As shown, the pouring of the first raft slab 1 provides a structural foundation for the subsequent placement of the post-pouring strip 7 in the backfilling construction method of the high and low span sections of the underground garage, which meets the construction specifications.
[0023] S2. After the concrete strength of the first raft slab 1, the second basement wall 2, and the second basement roof slab 3 meets the design requirements, waterproofing construction shall be carried out on the first raft slab 1 and the second basement wall 2; specifically, as follows... Figure 3 As shown, waterproofing construction on the bottom of the first raft slab 1 and the soil-facing surface of the second basement wall 2 can effectively prevent leakage in the underground garage's second basement level civil defense project.
[0024] S3. Modify slope protection 4, changing the original 1:1 natural slope structure of slope protection 4 into a stepped structure; specifically, as follows: Figure 2 and Figure 3 As shown, by modifying slope 4, the bearing capacity of slope 4 can be enhanced, thereby improving the stability of the backfill structure of the high and low span parts of the underground garage and reducing the risk of settlement in the later stage.
[0025] S4. Backfill liquid fly ash 5 between the second basement wall 2 and the slope protection 4. The liquid fly ash 5 is backfilled in layers and vibrated in place. The backfill height of liquid fly ash 5 is flush with the bottom of the first raft slab 1. After backfilling, surface finishing and curing are carried out; specifically, as follows... Figure 4As shown, replacing the original lime-soil backfill with liquid fly ash 5 has the following beneficial effects: Liquid fly ash 5 has high fluidity and can fill the corners and gaps between the basement wall 2 and the slope protection 4 by its own weight without the need for air compaction, avoiding the voids or gaps that are prone to occur in traditional backfilling and ensuring the compaction of the backfill; Liquid fly ash 5 has low shrinkage, and the fly ash particle size distribution is reasonable. When used with admixtures, the volume shrinkage rate after hardening is much lower than that of plain soil or gravel, which can reduce cracking of the backfill layer and avoid subsequent ground settlement. This reduces the risk of rework due to ground subsidence when the groundwater level is high. Liquid fly ash 5 uses industrial waste fly ash as its main raw material, turning waste into treasure, and is environmentally friendly, energy-saving, and pollution-free, meeting the requirements of green and civilized construction, improving the on-site construction image and safety factor. The strength of liquid fly ash 5 is controllable; by adjusting the cement dosage or admixture type, the hardened strength can be controlled between 1.2MPa and 3MPa, meeting the bearing capacity requirements for backfilling the high and low span sections of the underground garage without affecting subsequent foundation construction due to excessive strength. Furthermore, liquid fly ash 5 is poured backfill using a pump truck, which is more convenient than using a tower crane for lifting in lime-soil backfilling, greatly reducing the construction cycle, improving construction efficiency, and reducing labor and machinery costs.
[0026] S5. A second raft foundation 6 is poured onto the backfilled liquid fly ash 5. The upper surface of the second raft foundation 6 is flush with the upper surface of the first raft foundation 1. A post-pouring strip 7 is left between the second raft foundation 6 and the first raft foundation 1. Specifically, as follows... Figure 5 As shown, the upper surfaces of the second raft slab 6 and the first raft slab 1 are flush, serving together as the foundation for the underground parking garage on the first basement level. The placement of the post-cast strip 7 effectively prevents the second raft slab 6 and the first raft slab 1 from cracking due to shrinkage stress during the hardening process, thus improving the structural strength of the raft slab.
[0027] S6. After the concrete strength of the second raft slab 6 meets the design requirements, the post-cast strip 7 is poured. Specifically, after the concrete strength of the second raft slab 6 meets the design requirements, concrete is used to pour the post-cast strip 7, completing the backfilling construction of the high-low span section of the underground garage. It can be understood that the upper surface of the post-cast strip 7 is flush with the upper surface of the second raft slab 6 and the first raft slab 1.
[0028] Optionally, such as Figure 2 As shown, in step S1, scaffolding 9 is installed at the bottom for support during the pouring of the first raft slab 1. Scaffolding 9 provides a stable and reliable construction support system for the first raft slab 1, ensuring the structural safety, shape accuracy, and construction quality of the cantilevered portion during the pouring process, and laying a solid foundation for subsequent construction steps.
[0029] Furthermore, such as Figure 3 and Figure 6As shown, in step S1, multiple vent holes 11 are provided on the first raft slab 1. Each vent hole 11 penetrates the first raft slab 1 vertically, and a water-stop steel plate 12 is installed inside the wall of each vent hole 11. In step S4, when the liquid fly ash 5 is poured to the bottom of the first raft slab 1, the liquid fly ash 5 is vibrated through the multiple vent holes 11 to increase the slump of the liquid fly ash 5, ensuring that the liquid fly ash 5 below the first raft slab 1 is free of pores and densely filled. The water-stop steel plate 12 installed inside the vent hole 11 can effectively prevent groundwater or moisture from seeping up along the vent hole 11 later.
[0030] Specifically, the vent 11 is a square hole with a side length of 150mm, and the distance between two adjacent vent 11 is 5m. This size can ensure effective air exhaust and insertion of vibrator without excessively weakening the structural strength of the first raft slab 1. The reasonable spacing ensures the coverage of air exhaust and vibration, avoids local dead corners, and optimizes the construction effect and structural safety.
[0031] Furthermore, in step S6, multiple vent holes 11 need to be poured simultaneously with the pouring of the post-pouring strip 7. Pouring and filling the vent holes 11 at the same time as pouring the post-pouring strip 7 restores the structural integrity of the first raft slab 1, eliminates potential leakage points and structural defects in the first raft slab 1, and ensures the overall waterproof performance and structural strength of the first raft slab 1.
[0032] Optionally, such as Figure 3 As shown, in step S2, during the waterproofing construction of the first raft slab 1 and the second basement wall 2, the waterproof membrane 8 is continuously laid on the bottom of the first raft slab 1 and the side of the second basement wall 2 closest to the foundation pit. By continuously laying the waterproof membrane 8 on the soil-facing side of the second basement wall 2 and the bottom of the first raft slab 1, a complete and continuous waterproof layer is formed, effectively preventing the infiltration of external groundwater and soil moisture into the interior of the second basement level civil defense project of the underground garage, thus enhancing the waterproofing reliability of the underground garage.
[0033] Furthermore, such as Figure 3 As shown, in step S1, a steel bar 13 is pre-installed at one end of the first raft slab 1 away from the second basement wall 2 in the horizontal direction. A waterproof membrane 8 is laid on the lower part of the steel bar 13. Before backfilling the liquid fly ash 5 in step S4, the steel bar 13 and the waterproof membrane 8 are turned up and fixed. The steel bar 13 at the edge of the first raft slab 1 and the waterproof membrane 8 laid below it are easily damaged, displaced, or have failed to bond during subsequent backfilling construction, affecting the structural connection and waterproof continuity. By turning up and fixing the pre-installed steel bar 13 and the waterproof membrane 8 below it before backfilling, a dual protection effect is achieved: firstly, the steel bar 13 is protected from contamination, facilitating subsequent connection with the second raft slab 6; secondly, the effective overlap and sealing of the waterproof membrane 8 at the edge of the first raft slab 1 is ensured, maintaining the integrity of the waterproof system and providing a good interface for the subsequent pouring of the second raft slab 6.
[0034] Optionally, the angle between the reinforcing bar 13 and the waterproof membrane 8 after being flipped up and fixed and the horizontal plane is 30° to 90°. This angle range can ensure that the reinforcing bar 13 and the waterproof membrane 8 are effectively lifted and protected, avoiding being buried or damaged by the liquid fly ash 5, and is also feasible for construction, optimizing the construction operation and the final effect.
[0035] For example, in step S4, the liquid fly ash 5 includes fly ash particles, cement, and admixtures. Fly ash and cement provide strength and micro-expansion, while admixtures (such as water-reducing agents, retarders, etc.) optimize its fluidity and workability, ensuring that the liquid fly ash 5 has good pumpability, self-compacting properties, high strength, low shrinkage, and good stability after hardening.
[0036] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A backfilling construction method for high-low span parts between a negative second floor top plate and a foundation pit, characterized in that, The backfill construction method for high-low span parts of the underground garage comprises the following steps: S1, pouring the first raft (1), the first raft (1) and the negative two layer wall (2) and the negative two layer roof (3) are poured at one time, the upper end surface of the first raft (1) and the upper end surface of the negative two layer roof (3) are flush, the first raft (1) protrudes in the horizontal direction by one third of the horizontal distance of the negative two layer wall (2) from the foundation pit; S2, after the concrete strength of the first raft (1), the negative two layer wall (2) and the negative two layer roof (3) meets the design requirements, waterproof construction is performed on the first raft (1) and the negative two layer wall (2); S3, the slope protection (4) is trimmed, the original 1:1 natural slope structure of the slope protection (4) is trimmed into a stepped structure; S4, liquid fly ash (5) is backfilled between the negative two layer wall (2) and the slope protection (4), the liquid fly ash (5) is backfilled by layer pouring and vibration into place, the backfill height of the liquid fly ash (5) is flush with the bottom of the first raft (1), and surface curing is performed after backfilling is completed; S5, the second raft (6) is poured on the backfilled liquid fly ash (5), the upper end surface of the second raft (6) is flush with the upper end surface of the first raft (1), and a post-poured belt (7) is left between the second raft (6) and the first raft (1); S6, after the concrete strength of the second raft (6) meets the design requirements, the post-poured belt (7) is poured.
2. The construction method of claim 1, wherein, In the step S1, a plurality of air vents (11) are left on the first raft (1), each air vent (11) penetrates the first raft (1) in the vertical direction, and a water stop steel plate (12) is arranged in the hole wall of each air vent (11).
3. The construction method of claim 2, wherein, In the step S4, when the liquid fly ash (5) is poured below the first raft (1), the liquid fly ash (5) is vibrated through the plurality of air vents (11) to increase the slump degree of the liquid fly ash (5).
4. The method of claim 2, wherein the method further comprises: In the step S6, the post-poured belt (7) is poured at the same time as the plurality of air vents (11).
5. The method of claim 2, wherein the method further comprises: In the step S1, the air vent (11) is a square hole with a side length of 150mm, and the spacing between adjacent two air vents (11) is 5m.
6. The method of claim 1, wherein the method further comprises: In the step S2, when the waterproof construction is performed on the first raft (1) and the negative two layer wall (2), the waterproof coiled material (8) is continuously laid on the bottom of the first raft (1) and the side of the negative two layer wall (2) close to the foundation pit.
7. The construction method of claim 6, wherein, In the step S1, a steel bar (13) is reserved at the end of the first raft (1) away from the negative two layer wall (2) in the horizontal direction, the lower part of the steel bar (13) is laid with the waterproof coiled material (8), and the steel bar (13) and the waterproof coiled material (8) are fixed by turning up before the liquid fly ash (5) is backfilled in the step S4.
8. The method of claim 7, wherein the method further comprises: The angle between the steel bar (13) and the waterproof coiled material (8) after being fixed by turning up and the horizontal plane is 30° to 90°.
9. The method according to any one of claims 1 to 8, wherein, The liquid fly ash (5) comprises fly ash particles, cement and admixtures in the step S4.
10. The method according to any one of claims 1-8, wherein, The first raft (1) is supported by the scaffold (9) during pouring in the step S1.