Foundation with rock-filled layer liquefaction site

Abstract

The utility model discloses a foundation of a liquefaction site with a rock-filled layer, which belongs to the technical field of building foundations and sequentially comprises a raft foundation, a mattress layer, the rock-filled layer and a liquefaction layer from top to bottom, the rock-filled layer is provided with a plurality of seepage wells which are arranged in parallel and mutually independent, the seepage wells extend into the liquefaction layer, and the liquefaction layer is arranged on the raft foundation. The top of each seepage well is covered with a gravel layer, and the gravel layers are located in the mattress layer. A hollow pipe and coarse sand are arranged in each seepage well, the coarse sand is filled between the well wall of the seepage well and the outer wall of the hollow pipe, the hollow pipe is filled with gravel, and the seepage well is simple in construction, high in practicability and good in drainage performance.

Description

Technical Field

[0001] The utility model relates to the technical field of building foundations, in particular to a foundation with a liquefied site with a stone-filled layer. Background Art

[0002] In coastal projects, the sites are often severely liquefied. Many shallow layers of the ground have been treated with riprap and stone filling, and there is a layer of stone filling. The stone filling layer has a certain bearing capacity, which can reach 130kpa, but the uniformity is not good, so it is not suitable for natural foundations, and prefabricated pile foundations cannot be used for stone filling. Taking the slow road project as an example, the buildings are some single-story public toilets and management rooms, with small loads and small blocks. Considering the unevenness of the stone filling layer and the severe liquefaction of the site, the foundation engineering of the building mostly adopts cast-in-place pile foundations, and the piles are relatively long. Most of the cost is in the foundation engineering. Compared with buildings such as single-story public toilets, the economy is seriously unbalanced.

[0003] Prior art, such as the Chinese patent publication number CN110886306A, discloses an adaptive drainage and decompression system and method for liquefiable foundation of an underground comprehensive pipeline corridor. The system structure of the present invention constructs an interconnected drainage channel composed of gravel piles that pass through the liquefied stratum, water-conducting gravel blind ditches, and decompression pipe wells, which can discharge pore water in time.

[0004] The system construction in the above patent is relatively cumbersome, the pipeline structure is complex, and the installation method of driving is adopted, so that the smearing effect of the hole wall reduces the permeability coefficient and affects the drainage. Utility Model Content

[0005] The utility model provides a foundation with a liquefied site with a rock-filling layer, which has the advantages of simple construction, high practicability and good drainage performance.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] A foundation of a liquefied site with a rock-fill layer comprises, from top to bottom, a raft foundation, a cushion layer, a rock-fill layer and a liquefied layer, a plurality of infiltration wells are provided on the rock-fill layer, the plurality of infiltration wells are arranged in parallel and are independent of each other, the infiltration wells extend into the liquefied layer, the top of each infiltration well is covered with a crushed stone layer, the crushed stone layer is located in the cushion layer; a hollow tube and coarse sand are provided in each infiltration well, the coarse sand is filled between the well wall of the infiltration well and the outer wall of the hollow tube, and the hollow tube is filled with gravel.

[0008] The preferred technical solution of the utility model is that the hollow tube is configured as a sandless concrete hollow tube.

[0009] The preferred technical solution of the utility model is that the diameter of the hollow tube is between 150 mm and 250 mm.

[0010] The preferred technical solution of the utility model is that the mattress layer is filled with sand and gravel, and the thickness of the sand and gravel is between 400 mm and 600 mm.

[0011] The preferred technical solution of the utility model is that the depth of the infiltration well is between 5m and 10m, and the distance between adjacent infiltration wells is less than 5m.

[0012] The preferred technical solution of the utility model is that the bottom of the hollow tube is located at the bottom of the infiltration well, and the top of the hollow tube protrudes from the wellhead of the infiltration well and is located in the gravel layer.

[0013] The preferred technical solution of the utility model is that the infiltration well is set by drilling and implanting.

[0014] The beneficial effects of the utility model are:

[0015] (1) Through the combination of hollow pipes and infiltration wells, the sandless concrete hollow pipes can be permeable. The hollowness can increase the average permeability coefficient k, and the filled gravel will not be squeezed by the soil pressure.

[0016] (2) The construction of sand concrete hollow pipes for seepage wells is easy and more effective.

[0017] (3) The drilling and implantation method is adopted to avoid the smearing effect of the hole wall that reduces the permeability coefficient and affects drainage.

[0018] (4) The problem of uneven stone filling layer is solved by providing a cushion layer.

[0019] (5) The foundation adopts raft foundation to enhance the integrity and rigidity of the foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the foundation of a liquefied site with a rock-filling layer provided in a specific embodiment of the utility model;

[0021] Figure 2 It is a schematic diagram of the foundation structure of a liquefied site with a rock-fill layer provided in a specific embodiment of the utility model;

[0022] Figure 3 It is a schematic diagram of the principle of the overall structure of the foundation of the liquefied site with a rock-filling layer provided in a specific embodiment of the utility model;

[0023] Figure 4 It is a schematic diagram of the foundation layout of a liquefied site with a rock-fill layer provided in a specific embodiment of the utility model;

[0024] In the figure:

[0025] 1. Raft foundation; 2. Cushion layer; 3. Stone filling layer; 4. Liquefaction layer; 5. Seepage well; 501. Hollow pipe; 502. Coarse sand; 503. Gravel; 6. Gravel layer. DETAILED DESCRIPTION

[0026] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0027] like Figure 1-4 As shown, the utility model provides a foundation of a liquefied site with a stone-filled layer 3, which includes a raft foundation 1, a cushion layer 2, a stone-filled layer 3 and a liquefied layer 4 from top to bottom. A plurality of infiltration wells 5 are opened on the cushion layer 2, and the infiltration wells 5 extend into the liquefied layer 4. The infiltration wells 5 are covered with a crushed stone layer 6 to form a closure. The infiltration wells 5 are basically used for active pumping to lower the groundwater level or consolidate soft soil in foundation pit projects, and are often used as channels for surface water to be discharged into the underground in road projects. A plurality of infiltration wells 5 are arranged in parallel on the cushion layer 2, and each infiltration well 5 is independent of each other. The setting of the infiltration wells 5 should be carried out by drilling and implanting. Compared with the driving method, the smearing effect of the hole wall is avoided, the permeability coefficient is reduced, and the drainage is affected.

[0028] In order to ensure the drainage channel and increase the permeability coefficient, each infiltration well 5 is filled with a hollow pipe 501. As a permanent facility, it is not appropriate to use PVC pipes, etc. Therefore, the hollow pipe 501 is set as a sandless concrete hollow pipe 501. The sandless concrete is water-permeable, and the hollowness can increase the average permeability coefficient k. The hollow pipe 501 is filled with gravel, and the hollow pipe 501 and the infiltration well 5 are filled with coarse sand 502. The filled gravel material will not be squeezed by the soil pressure. The hollow pipe 501 is easy to construct as an infiltration well 5 and is more effective. The infiltration well 5 is completed by digging holes, laying pipes, backfilling coarse sand 502, and backfilling gravel. And because it is not a drilling implantation method, it avoids the smearing effect of the hole wall to reduce the permeability coefficient and affect drainage. Through gravel, coarse sand 502 and crushed stone layer 6, the infiltration well 5 forms a ring-shaped closure within the foundation range.

[0029] Since the seepage well 5 of this scheme is a passive pressure relief, and is not mainly for drainage. During an earthquake, the soil is squeezed, and the excess static pore water pressure is generated. With the seepage well 5, water flows to the seepage well 5, releasing the excess hydrostatic pressure, and the soil will not lose shear strength, and liquefaction settlement will be partially eliminated. The drainage volume is not large, mainly because the water pressure needs to have a release space, so the diameter of the seepage well 5 does not need to be too large, and the diameter of the seepage well 5 only needs to be slightly larger than the diameter of the hollow pipe 501. The diameter of the hollow pipe 501 is between 150㎜-250㎜, preferably 200㎜, and the seepage well 5 with a small diameter is more feasible. It is difficult to drill a large hole in the seepage well 5 in the rock filling layer 3, and the small diameter reduces the construction difficulty and construction cost. The depth of the seepage well 5 is between 5m-10m, and the spacing between adjacent seepage wells 5 should be less than 5m.

[0030] Through the cushion layer 2, the cushion layer 2 is filled with sand and gravel, and the thickness of the sand and gravel is between 400㎜-600㎜, which solves the uneven problem of the stone filling layer 3. The foundation can adopt a raft foundation 1 to enhance the integrity and rigidity of the foundation, avoid the cast-in-place pile foundation, reduce costs, reduce construction difficulty, and improve economy.

[0031] The bottom of the hollow pipe 501 is located at the bottom of the infiltration well 5, and the top of the hollow pipe 501 protrudes from the wellhead of the infiltration well 5 and is located in the gravel layer 6, which is convenient for maintenance and management, and can be inspected, repaired and cleaned more conveniently. This helps to maintain the normal operation of the infiltration well 5 and extend its service life. It enhances the structural stability of the infiltration well 5, and can reinforce the well wall of the infiltration well 5 to improve its structural stability. It prevents blockage and prevents external debris from entering the infiltration well 5, reducing the risk of blockage. It is convenient to connect other drainage facilities. The infiltration well 5 may need to be connected to other drainage facilities (such as drainage ditches, rainwater pipes, etc.). When the hollow pipe 501 protrudes from the mouth of the infiltration well 5, it is more convenient to perform the connection operation, thereby improving the overall efficiency of the drainage system.

[0032] In summary, according to the Code for Seismic Design of Buildings GB50011-2010, the building is a Class C building, and the liquefaction level is Class B. The anti-liquefaction measures can be "partially eliminating liquefaction settlement and treating the foundation and superstructure", using 5 groups of seepage wells to partially eliminate liquefaction settlement, using raft foundation 1 to treat the foundation and superstructure, using cushion layer 2 as a horizontal drainage channel, and coordinating stiffness, using stone filling as a bearing layer. It can effectively treat single and multi-layer foundations in coastal areas with liquefied sites with stone filling layer 3.

[0033] The present invention is described by preferred embodiments, and those skilled in the art will appreciate that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. The present invention is not limited to the specific embodiments disclosed herein, and other embodiments falling within the claims of this application are within the scope of protection of the present invention.

Claims

1. A foundation for a liquefied site with a rock-fill layer, characterized in that: From top to bottom, it comprises a raft foundation (1), a cushion layer (2), a stone filling layer (3) and a liquefied layer (4), a plurality of infiltration wells (5) are opened on the stone filling layer (3), the plurality of infiltration wells (5) are arranged in parallel and are independent of each other, the infiltration wells (5) extend into the liquefied layer (4), the top of each infiltration well (5) is covered with a crushed stone layer (6), and the crushed stone layer (6) is located in the cushion layer (2); Each of the infiltration wells (5) is provided with a hollow tube (501) and coarse sand (502), wherein the coarse sand (502) is filled between the wall of the infiltration well (5) and the outer wall of the hollow tube (501), and the hollow tube (501) is filled with gravel (503).

2. The foundation of the liquefied site with rock-fill layer according to claim 1, characterized in that: The hollow tube (501) is configured as a sandless concrete hollow tube (501).

3. The foundation of the liquefied site with rock-fill layer according to claim 1, characterized in that: The diameter of the hollow tube (501) is between 150 mm and 250 mm.

4. The foundation of a liquefied site with a rock-fill layer according to claim 1, characterized in that: The cushion layer (2) is filled with sand and gravel, and the thickness of the sand and gravel is between 400 mm and 600 mm.

5. The foundation of a liquefied site with a rock-fill layer according to claim 1, characterized in that: The depth of the infiltration well (5) is between 5m and 10m, and the distance between adjacent infiltration wells (5) is less than 5m.

6. The foundation of the liquefied site with rock-fill layer according to claim 1, characterized in that: The bottom of the hollow tube (501) is located at the bottom of the infiltration well (5), and the top of the hollow tube (501) protrudes from the wellhead of the infiltration well (5) and is located in the gravel layer (6).

7. The foundation of a liquefied site with a rock-fill layer according to claim 1, characterized in that: The infiltration well (5) is set by drilling and implanting.

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