A piece stone backfill structure for soft soil shallow foundation pit

Abstract

The utility model relates to the field of slice stone replacement, specifically refers to a slice stone replacement structure for soft soil shallow foundation pit, including soft weak underlayer, gravel cushion, slice stone main body replacement layer, stone chippings leveling layer and upper structure cushion, the utility model has the advantages compared with prior art: through the slice stone of multilayer tamping as core, using the chippings to fill and level it, the upper and lower sides are laid concrete and gravel, so that the slice stone replacement structure in soft soil shallow foundation pit has the advantages such as high bearing capacity, good drainage, small settlement, economic and practical and ecological environmental protection.

Description

Technical Field

[0001] This utility model relates to the field of rubble replacement, specifically a rubble replacement structure for shallow foundation pits in soft soil. Background Technology

[0002] When excavating shallow foundation pits in soft soil areas, problems such as insufficient bearing capacity, high compressibility, and poor drainage are often encountered, which makes the soil at the bottom of the foundation pit prone to plastic failure, excessive settlement or heave, directly affecting the safety and normal use of the superstructure. Traditional plain soil or lime-soil replacement often has limited effectiveness, while pile foundations are costly and have a long construction period. Therefore, an economical, effective, and easy-to-construct shallow foundation treatment solution is needed. Utility Model Content

[0003] I. Technical problems to be solved The technical problem this invention aims to solve is that shallow foundation pits in soft soil areas, which are currently filled with plain soil, have shortcomings such as poor bearing capacity, easy settlement, or uneven settlement.

[0004] Technical solution To solve the above-mentioned technical problems, the technical solution provided by this utility model is: a rubble replacement structure for shallow foundation pits in soft soil, comprising: The layers laid from bottom to top on the ground are: a soft underlying layer, a gravel cushion layer, a rubble main replacement layer, a stone chip leveling layer, and an upper structural cushion layer.

[0005] The weak underlying layer is the original soft soil layer at the bottom of the foundation pit after treatment.

[0006] The gravel cushion layer is formed by stacking gravel to form a cushion layer of 300mm-500mm.

[0007] The main replacement layer of the rubble is made by backfilling the shallow foundation pit in layers with high-strength, weather-resistant rubble or blocks.

[0008] The stone chip leveling layer uses crushed stone chips, which are incorporated into the gaps at the top of the rubble main replacement layer, forming a 150mm-300mm cushion layer on top of the rubble main replacement layer.

[0009] The upper structural cushion layer is made of plain concrete.

[0010] Furthermore, the main replacement layer of the rubble stone adopts a layered backfilling and compaction method, with each backfill layer not exceeding 500mm in thickness, and the total thickness H of the main replacement layer of the rubble stone is determined by calculation.

[0011] Furthermore, the total thickness H of the main rubble replacement layer is determined by calculating the bearing capacity and settlement of the top surface of the weak underlying layer.

[0012] Furthermore, the width of the bottom surface of the main rubble replacement layer should extend beyond the edge of the foundation bottom surface, calculated according to the pressure diffusion angle, and the width on each side should be no less than 500mm.

[0013] Furthermore, the rubble has a saturated compressive strength ≥30MPa, a maximum particle size ≤2 / 3 of the thickness of each layer, and is free of weathered stones, organic matter, and other impurities.

[0014] Beneficial effects The advantages of this utility model compared with the prior art are as follows: 1. High bearing capacity: The rubble skeleton plays a significant role, providing a foundation bearing capacity of 150kPa-300kPa or higher; 2. Good drainage: High porosity, which can accelerate the consolidation of underlying soft soil and improve long-term stability; 3. Small settlement: The high-strength, low-compressibility rubble layer can effectively reduce total settlement and uneven settlement; 4. Economical and practical: It makes full use of local stone materials, and the cost is much lower than that of pile foundations, and the construction speed is fast; 5. Eco-friendly: Made from natural materials, with no pollution. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the internal end face of a rubble replacement structure for shallow foundation pits in soft soil, according to this utility model.

[0016] Figure 2 This is a schematic diagram of the land cross-section in a rubble replacement structure for shallow foundation pits in soft soil, according to this utility model.

[0017] Figure 3 yes Figure 2 A schematic diagram of the structure of part A.

[0018] As shown in the figure: 1. Upper structural cushion layer, 2. Stone chip leveling layer, 3. Stone main body replacement layer, 4. Gravel cushion layer, 5. Weak underlying layer. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings.

[0020] To solve the above-mentioned technical problems, the technical solution provided by this utility model is: a rubble replacement structure for shallow foundation pits in soft soil, combined with attached... Figure 1-2 It includes: a soft underlying layer 5, a gravel cushion layer 4, a rubble main replacement layer 3, a stone chip leveling layer 2, and an upper structural cushion layer 1, laid sequentially from bottom to top on the ground. Among them, the weak underlying layer 5 is the original soft soil layer at the bottom of the foundation pit after treatment.

[0021] The gravel cushion layer is made by piling up gravel. In the extremely soft bottom of the foundation pit, it can be laid in advance to form a cushion layer of 300mm-500mm, which can prevent the rubble from sinking, isolate silt and assist in horizontal drainage. The main replacement layer 3 of the rubble is made of high-strength, weather-resistant rubble or boulders, and the shallow foundation pit is backfilled in layers. The main replacement layer 3 of the rubble is backfilled in layers and compacted layer by layer, and the thickness of each backfill layer does not exceed 500mm. The compaction process uses heavy machinery for rolling or dynamic compaction to form a dense whole. The standard for quality control is a compaction coefficient ≥0.96 or the difference in on-site settlement, i.e., the difference in elevation between the last two rolling passes ≤2mm. The total thickness H of the main rubble replacement layer 3 is determined by calculating the bearing capacity and settlement of the top surface of the weak underlying layer 5, and is usually between 1000mm and 3000mm. The width of the bottom surface of the main stone replacement layer 3 should extend beyond the edge of the foundation bottom surface. Calculated according to the pressure diffusion angle, it is usually 30-45 degrees, and the width on each side should not be less than 500mm. The rubble has a saturated compressive strength ≥30MPa, a maximum particle size ≤2 / 3 of the thickness of each layer, and is free of weathered stones, organic matter, and other impurities. Leveling layer 2 uses crushed stone, combined with... Figure 3 This allows it to enter the gap at the top of the main stone replacement layer 3, and forms a 150mm-300mm pad layer at the top of the main stone replacement layer 3, providing a flat and uniform stress surface. The upper structure cushion layer 1 is made of plain concrete and is located on top of the replacement structure, directly bearing the upper load.

[0022] In practical implementation, this utility model utilizes the rubble replacement structure to fill and pave shallow foundation pits in soft soil. The construction steps are as follows: S1: Excavation and drainage of the foundation pit: Excavate to the design elevation, and set up drainage ditches and sump pits around the pit to keep the bottom dry; S2: Foundation Acceptance: Inspect the foundation soil quality, remove silt and debris, and lay a gravel cushion layer as an isolation layer; S3: Layered backfilling and compaction: • Laying materials: Lay the rubble in layers according to the calculated thickness, such as 400mm-500mm; • Compaction: Vibratory rollers or heavy rammers are used for compaction. The route is from both sides to the middle. The number of compaction passes is determined by test. After that, the main replacement layer of rubble stone is formed. • Joint filling: After the large-diameter rubble is compacted, the surface gaps are filled with smaller stones or stone chips, and then statically pressed to stabilize it. Then, stone chips are used to fill the gaps between the rubble, making the rubble main body replacement layer 3, which is the core part of the structure, dense. S4: Quality inspection: The bearing capacity is tested by dynamic cone penetration test (N63.5) or plate load test, and the compaction degree and settlement difference are detected. S5: Leveling and Subbase Construction: Lay a graded crushed stone leveling layer and compact it. Stone chips continue to accumulate on the main stone replacement layer 3 with a thickness of 300mm-500mm. Then, pour a concrete subbase as the upper structural subbase 1.

[0023] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A rubble replacement structure for shallow foundation pits in soft soil, characterized in that, include: The layers laid from bottom to top on the ground are: a soft underlying layer (5), a gravel cushion layer (4), a rubble main replacement layer (3), a stone chip leveling layer (2), and an upper structural cushion layer (1). The weak underlying layer (5) is the original soft soil layer at the bottom of the foundation pit after treatment; The gravel cushion layer (4) is formed by stacking gravel to form a cushion layer of 300mm-500mm; The main replacement layer (3) of the rubble is filled in layers with high-strength, weather-resistant rubble to backfill the shallow foundation pit; The stone chip leveling layer (2) uses crushed stone chips, which are then incorporated into the gaps at the top of the rubble main body replacement layer (3), forming a 150mm-300mm cushion layer at the top of the rubble main body replacement layer (3). The upper structural cushion layer (1) is made of plain concrete.

2. The rubble replacement structure for shallow foundation pits in soft soil according to claim 1, characterized in that: The main replacement layer (3) of the rubble is backfilled in layers and compacted layer by layer. The thickness of each backfill layer does not exceed 500mm. The total thickness H of the main replacement layer (3) of the rubble is determined by calculation.

3. The rubble replacement structure for shallow foundation pits in soft soil according to claim 2, characterized in that: The total thickness H of the main rubble replacement layer (3) is determined by calculating the bearing capacity and settlement of the top surface of the weak underlying layer (5).

4. The rubble replacement structure for shallow foundation pits in soft soil according to claim 1, characterized in that: The bottom width of the main stone replacement layer (3) should extend beyond the edge of the foundation bottom surface, calculated according to the pressure diffusion angle, and the width on each side should not be less than 500mm.

5. The rubble replacement structure for shallow foundation pits in soft soil according to claim 1, characterized in that: The rubble has a saturated compressive strength of ≥30MPa, a maximum particle size of ≤2 / 3 of the thickness of each layer, and is free of weathered stone and organic impurities.

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