Construction method of underground cantilever structure fat groove backfill

Abstract

The construction method of the underground overhanging structure fertilizer groove backfilling comprises the following steps: S1, the fertilizer groove is divided into a lower backfilling area, a middle filling area and an upper backfilling area, the middle filling area is located directly below the overhanging part, the lower backfilling area is located below the middle filling area, the upper backfilling area is located above the lower backfilling area, the height of the middle filling area is 2.0-2.1 meters, and the width of the middle filling area is 0.5-0.8 meters larger than the width of the overhanging part; S2, the building outer wall and the bottom surface of the overhanging part are respectively waterproofed; S3, the lower backfilling area is backfilled; S4, a filling and soil retaining structure with an inner cavity is constructed in the middle filling area, the filling and soil retaining structure is closely attached to the surface of the soil layer of the lower backfilling area, and the overhanging part serves as the top of the filling and soil retaining structure; S5, the filling and soil retaining structure is filled with foam concrete; and S6, the upper backfilling area is backfilled. The application effectively reduces the risk of uneven settlement of backfilling earthwork, improves the construction efficiency, saves labor, and is economical and practical.

Description

Technical Field

[0001] This invention relates to a construction method for backfilling underground cantilever structures, belonging to the field of foundation pit backfilling. Background Technology

[0002] Foundation trenches are a crucial component in building construction, ensuring structural safety and functional integrity. Inadequate compaction or rolling of backfill soil, resulting in insufficient density to meet specifications and design requirements, can easily lead to surface water infiltration and soil subsidence. Particularly at the bottom of cantilevered sections, where compaction equipment may not reach a certain area, inadequate compaction of the backfill soil can cause soil from other areas to slide into that area later, resulting in significant uneven settlement of the entire foundation trench. This can lead to cracking or even damage to structures built in the backfilled area, resulting in substantial repair costs.

[0003] To address the issue of insufficient compaction of the backfill soil at the bottom of the cantilever section, some existing technologies seal and isolate the bottom of the cantilever section, eliminating the need for backfill soil compaction. For example, CN202223318582.7 discloses a flexible retaining structure for cantilever sections in trench backfilling. However, during actual construction, the layered backfilling and compaction of the soil layers can compress the retaining structure, causing deformation or even damage, thus failing to compact the backfill soil and achieve synchronous settlement with it. Other technologies employ a reverse construction method, introducing a construction joint at the cantilever section. The main body is constructed first, and the cantilever section is constructed only after backfilling to the bottom. This delays the overall completion time, impacting the construction schedule. Furthermore, the introduction of construction joints increases the risk of leakage at this location. Therefore, further optimization of the construction method for filling and compacting the bottom of the cantilever section is needed. Summary of the Invention

[0004] The construction method for backfilling underground cantilever structures provided by this invention reduces the lateral load on the exterior wall, replaces the soil layer at the bottom of the cantilever with foamed concrete, reduces weight and vertical load, solves the problem of insufficient compaction of the backfill soil at the bottom of the cantilever, effectively reduces the risk of uneven settlement of the backfill soil, thereby reducing safety hazards, improving construction efficiency, saving labor, and being economical and practical.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A construction method for backfilling trenches in underground cantilever structures, characterized by the following construction steps:

[0007] S1, the fertilizer tank is divided into a lower backfill area, a middle backfill area and an upper backfill area. The middle backfill area is located directly below the cantilevered part, the lower backfill area is located below the middle backfill area, and the upper backfill area is located above the lower backfill area. The height of the middle backfill area is 2.0~2.1 meters and the width is 0.5~0.8 meters greater than the width of the cantilevered part.

[0008] S2, waterproofing treatment is applied to the exterior walls and the bottom of the cantilevered parts of the building respectively;

[0009] S3, Backfilling construction is carried out on the lower backfill area;

[0010] S4, Construct a filling retaining structure with an inner cavity in the middle filling area. The filling retaining structure is in close contact with the soil surface of the lower backfill area, and the cantilevered part serves as the top of the filling retaining structure.

[0011] S5, fill the retaining structure with foamed concrete;

[0012] S6, backfilling construction is carried out on the upper backfill area.

[0013] Preferably, step S4 specifically refers to:

[0014] First, a cushion layer is constructed on the surface of the soil layer in the lower backfill area, which is in contact with the waterproof layer on the building's exterior wall. The cushion layer is the same length as the cantilevered part, and its width is greater than the width of the cantilevered part. The distance between the cushion layer and the cantilevered part is not less than 1.8 meters.

[0015] Then, a retaining wall is built at the outer end of the foundation layer. The retaining wall contacts the building exterior wall and the cantilevered part respectively. The building exterior wall, the cantilevered part, the foundation layer and the retaining wall together form a filling retaining structure.

[0016] Preferably, while constructing the retaining wall, a partition wall is also constructed on the subgrade. The partition walls are evenly spaced along the length of the subgrade, dividing the inner cavity of the filling retaining structure into multiple partition cavities.

[0017] Preferably, during the construction of the retaining wall, the pouring port for each compartment is formed by adjusting the distance between the retaining wall and the cantilevered part.

[0018] Preferably, the retaining wall has multiple evenly spaced protrusions along the length of the cushion layer. The protrusions are located on the outside of the cantilevered part and are flush with the top surface of the cantilevered part, forming a pouring port between the protrusions and the cantilevered part.

[0019] Preferably, the width of the partition cavity is 8±0.5 meters, the interval between adjacent pouring gates is 3.5±0.5 meters, and the width of the pouring gate is 30±5 centimeters.

[0020] Preferably, “waterproofing treatment is applied to the exterior walls and the bottom of the cantilevered parts of the building” specifically means first applying waterproof membrane to the exterior walls and the bottom of the cantilevered parts of the building, and then applying extruded polystyrene board to the waterproof membrane.

[0021] Preferably, the thickness of the cushion layer is no more than 20 centimeters, and the cushion layer is formed by pouring concrete on the surface of the soil layer in the lower backfill area.

[0022] Preferably, the thickness of the retaining wall is 35±5 cm, and the thickness of the partition wall is less than the thickness of the retaining wall.

[0023] The beneficial effects of the invention are:

[0024] In this invention, the backfill trench is first divided into a lower backfill area, a middle backfill area, and an upper backfill area. After the lower backfill area is backfilled, a hollow retaining structure is constructed in the middle backfill area. Foamed concrete is injected into the retaining structure to enclose the space at the bottom of the cantilever that the compaction equipment cannot access, and then fill it with foamed concrete. Foamed concrete is a rigid body with good bonding properties and does not exert lateral pressure on the building's exterior walls, thus reducing the lateral load on the exterior walls. Moreover, the filling of the retaining structure with foamed concrete can prevent the retaining structure from deforming and breaking due to the compression of the soil layer. Replacing the soil layer at the bottom of the cantilever with foamed concrete reduces the weight, lowers the vertical load, solves the problem of insufficient compaction of the backfill soil at the bottom of the cantilever, effectively reduces the risk of uneven settlement of the backfill soil, and thus reduces safety hazards.

[0025] The cavity inside the retaining structure is divided into multiple compartments by partition walls. Foamed concrete is then poured into each compartment through a pouring port to ensure the fullness of the foamed concrete inside the retaining structure. This ensures the compactness of the backfill in the intermediate filling area, improves the operability of pouring foamed concrete into the retaining structure, increases construction efficiency, saves labor, and is economical and practical. Attached Figure Description

[0026] Figure 1 A schematic diagram of constructing a filling retaining structure in the middle filling area of ​​the fertilizer trench.

[0027] Figure 2 This is a schematic diagram showing the formation of a pouring gate between the protruding part and the cantilevered part.

[0028] Figure 3 This is a schematic diagram of the construction of a retaining wall.

[0029] Figure 4 This diagram shows the division of the fertilizer tank into a lower backfill area, a middle filling area, and an upper backfill area. Detailed Implementation

[0030] The following is combined Figures 1-4The embodiments of the present invention will be described in detail below.

[0031] A construction method for backfilling trenches in underground cantilever structures, characterized by the following construction steps:

[0032] S1, the fertilizer tank is divided into a lower backfill area 1, a middle backfill area 2 and an upper backfill area 3. The middle backfill area 2 is located directly below the cantilevered part 4, the lower backfill area 1 is located below the middle backfill area 2, and the upper backfill area 3 is located above the lower backfill area 1. The height of the middle backfill area 2 is 2.0~2.1 meters, and the width is 0.5~0.8 meters greater than the width of the cantilevered part 4.

[0033] S2, waterproofing treatment shall be applied to the bottom surfaces of the building's exterior wall 5 and the cantilevered portion 4 respectively;

[0034] S3, carry out backfilling construction on the lower backfill area 1;

[0035] S4, construct a filling retaining structure 6 with an inner cavity in the middle filling area 2. The filling retaining structure 6 is closely attached to the soil surface of the lower backfill area 1, and the cantilever part 4 serves as the top of the filling retaining structure 6.

[0036] S5, fill the retaining structure 6 with foamed concrete;

[0037] S6, backfilling construction is carried out on the upper backfill area 3.

[0038] In the above-described construction method for backfilling the underground cantilever structure trench, the trench is first divided into a lower backfill area 1, a middle backfill area 2, and an upper backfill area 3. After backfilling the lower backfill area 1, a hollow retaining structure 6 is constructed in the middle backfill area 2. Foamed concrete is injected into the retaining structure 6, which encloses the space at the bottom of the cantilever 4 that the compaction equipment cannot access, forming the retaining structure 6 and filling it with foamed concrete. Foamed concrete is a rigid body with good bonding properties and does not exert lateral pressure on the building's exterior walls, reducing the lateral load on the exterior walls. Moreover, the filling of the retaining structure with foamed concrete can prevent the retaining structure from deforming and breaking due to the compression of the soil layer. Replacing the soil layer at the bottom of the cantilever with foamed concrete reduces the weight, lowers the vertical load, solves the problem of insufficient compaction of the backfill soil at the bottom of the cantilever, effectively reduces the risk of uneven settlement of the backfill soil, and thus reduces safety hazards.

[0039] Preferably, step S4 specifically refers to:

[0040] First, a cushion layer 7 is constructed on the soil surface of the lower backfill area 1, which is in contact with the waterproof layer on the building exterior wall 5. The cushion layer 7 is equal in length to the cantilever part 4, and its width is greater than the width of the cantilever part 4. The distance between the cushion layer 7 and the cantilever part 4 is not less than 1.8 meters.

[0041] Then, a retaining wall 8 is built at the outer end of the foundation layer 7. The retaining wall 8 contacts the building exterior wall 5 and the cantilevered part 4 respectively. The building exterior wall 5, the cantilevered part 4, the foundation layer 7, and the retaining wall 8 together form a filled retaining structure 6. After the foundation layer 7 is formed, workers can enter between the foundation layer 7 and the cantilevered part 4 to construct the retaining wall 8. Therefore, the distance between the foundation layer 7 and the cantilevered part 4 is not less than 1.8 meters to allow for manual construction. The retaining wall 8 is constructed and encloses the space below the cantilevered part 4, forming an inner cavity. Foamed concrete is injected into the inner cavity, that is, the space below the cantilevered part 4 that cannot be accessed by the compaction equipment is filled with foamed concrete. Foamed concrete replaces the compacted soil layer. The foundation layer 7 and the retaining wall 8 separate the soil layer from the foamed concrete, avoiding the problem of uneven settlement of the backfill soil caused by insufficient compaction of the backfill soil at the bottom of the cantilevered part. This effectively reduces the risk of uneven settlement of the backfill soil and thus reduces safety hazards.

[0042] During the construction of the retaining wall 8, partition walls 9 are also constructed on the foundation layer 7. The partition walls 9 are evenly spaced along the length of the foundation layer 7, dividing the inner cavity of the infill retaining structure 6 into multiple partitioned cavities 61. The partition walls 9 divide the inner cavity of the infill retaining structure into multiple partitioned cavities 61, and each partitioned cavity 61 is filled with foamed concrete to ensure the fullness of the foamed concrete inside the infill retaining structure 6. This ensures the compactness of the backfill in the intermediate filling area 2, improves the operability of pouring foamed concrete in the infill retaining structure 4, increases construction efficiency, saves labor, and is economical and practical.

[0043] During the construction of the retaining wall 8, the spacing between the retaining wall 8 and the cantilevered part 4 is adjusted to form the pouring port 10 for each partition cavity. During the construction of the retaining wall 8, the pouring port 10 is formed by moving the retaining wall outward and separating it from the cantilevered part. The size and number of pouring ports 10 are arranged according to the width of the partition cavity 61 to ensure the efficiency of pouring.

[0044] The retaining wall 8 has multiple evenly spaced protrusions 81 along the length of the cushion layer 7. The protrusions 81 are located on the outside of the cantilevered portion 4 and are flush with the top surface of the cantilevered portion 4. A pouring gate is formed between the protrusions 81 and the cantilevered portion 4. The protrusions 81 do not contact the cantilevered portion 4 and are located on the outside of the cantilevered portion 4. The two are separated to form a pouring gate 10, which is located at the top of the partition cavity to ensure the reliability of the pouring.

[0045] The partition cavity 61 has a width of 8±0.5 meters, the adjacent pouring ports 10 are spaced 3.5±0.5 meters apart, and the pouring port 10 has a width of 30±5 centimeters. This ensures the pouring efficiency of each partition cavity.

[0046] Specifically, "waterproofing treatment of the bottom surfaces of the building's exterior wall 5 and the cantilevered portion 4" refers to first applying a waterproof membrane to the bottom surfaces of the building's exterior wall 5 and the cantilevered portion 4, and then applying an extruded polystyrene board to the waterproof membrane. Using the extruded polystyrene board to protect the waterproof membrane effectively prevents deformation, sagging, and blistering of the waterproof membrane, thus improving waterproofing reliability.

[0047] The thickness of the cushion layer 7 is no more than 20 centimeters, and it is formed by pouring concrete onto the surface of the soil layer in the lower backfill area. The cushion layer 7 is formed by concrete pouring and is firm and reliable.

[0048] The retaining wall 8 has a thickness of 35±5 cm, while the partition wall 9 has a thickness less than that of the retaining wall 8. The greater thickness of the retaining wall 8 allows it to withstand the compression of the backfill soil in the upper backfill area, while the smaller thickness of the partition wall 9 reduces the filling weight in the middle filling area, thus reducing the overall mass and vertical load.

[0049] The technical solutions of the embodiments of the present invention have been fully described above with reference to the accompanying drawings. It should be noted that the described embodiments are only a part of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A construction method for backfilling trenches in underground cantilever structures, characterized in that, The construction steps include: S1, the fertilizer tank is divided into a lower backfill area, a middle backfill area and an upper backfill area. The middle backfill area is located directly below the cantilevered part, the lower backfill area is located below the middle backfill area, and the upper backfill area is located above the lower backfill area. The height of the middle backfill area is 2.0~2.1 meters and the width is 0.5~0.8 meters greater than the width of the cantilevered part. S2, waterproofing treatment is applied to the exterior walls and the bottom of the cantilevered parts of the building respectively; S3, Backfilling construction is carried out on the lower backfill area; S4, Construct a filling retaining structure with an inner cavity in the middle filling area. The filling retaining structure is in close contact with the soil surface of the lower backfill area, and the cantilevered part serves as the top of the filling retaining structure. S5, fill the retaining structure with foamed concrete; S6, Backfilling construction is carried out on the upper backfill area; Step S4 specifically refers to: First, a cushion layer is constructed on the surface of the soil layer in the lower backfill area, which is in contact with the waterproof layer on the building's exterior wall. The cushion layer is the same length as the cantilevered part, and its width is greater than the width of the cantilevered part. The distance between the cushion layer and the cantilevered part is not less than 1.8 meters. Then, a retaining wall is built at the outer end of the foundation layer. The retaining wall contacts the building exterior wall and the cantilevered part respectively. The building exterior wall, the cantilevered part, the foundation layer and the retaining wall together form a filling retaining structure. While constructing the retaining wall, partition walls are constructed on the foundation layer. The partition walls are evenly spaced along the length of the foundation layer, dividing the inner cavity of the filling retaining structure into multiple partition cavities. During the construction of the retaining wall, the pouring port for each compartment is formed by adjusting the distance between the retaining wall and the cantilevered part; The retaining wall has multiple evenly spaced protrusions along the length of the foundation layer. The protrusions are located on the outside of the cantilevered part and are level with the top surface of the cantilevered part. A pouring port is formed between the protrusions and the cantilevered part.

2. The construction method for backfilling the trench of an underground cantilever structure according to claim 1, characterized in that: The width of the partition cavity is 8±0.5 meters, the interval between adjacent pouring gates is 3.5±0.5 meters, and the width of the pouring gate is 30±5 centimeters.

3. The construction method for backfilling the trench of an underground cantilever structure according to claim 1, characterized in that: "Waterproofing the exterior walls and the bottom of the cantilevered parts of the building" specifically means first pasting waterproof membrane onto the exterior walls and the bottom of the cantilevered parts of the building, and then pasting extruded polystyrene board onto the waterproof membrane.

4. The construction method for backfilling the trench of an underground cantilever structure according to claim 1, characterized in that: The thickness of the cushion layer is no more than 20 centimeters, and it is formed by pouring concrete on the surface of the soil layer in the lower backfill area.

5. The construction method for backfilling the trench of an underground cantilever structure according to claim 1, characterized in that: The thickness of the retaining wall is 35±5 cm, and the thickness of the partition wall is less than that of the retaining wall.

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