Seepage draining and reinforcing structure for large-area sludge foundation treatment construction

Abstract

The utility model discloses a seepage draining and reinforcing structure for large-area sludge foundation treatment construction. The seepage draining and reinforcing structure is formed by combining a gravel soil material separation dam (1), a geotechnical blind ditch (2), a geogrid (3), a water collecting pool (4), a water collecting well (5), a lifting pump (6) and an outer drainage pipe (6 '). The gravel soil material separation dams (1) are arranged on the sludge foundation (8) according to grids shaped like a Chinese character'tian 'to form a criss-cross structure shaped like a Chinese character'tian'; and the geotechnical blind ditch (2) is arranged at the middle lower part of the gravel soil material separation dam (1). Compared with a traditional pile foundation scheme, a separation dam mode is adopted for treatment, the treatment period is shortened by more than 40%, the comprehensive cost is reduced by more than 65%, and the foundation bearing capacity is improved to more than 150 kPa; according to the utility model, the problems that the traditional silt foundation treatment construction method is high in cost, long in period, low in foundation bearing capacity and difficult to be used for the treatment construction of the large-area silt foundation are effectively solved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to geotechnical engineering technical field, concretely relates to a kind of seepage drainage reinforcement structure for large-area silt soft soil foundation treatment construction. BACKGROUND

[0002] Silt foundation refers to the foundation soil layer mainly composed of silt (Muck Soil / Silt Soil), which belongs to typical soft soil foundation type, and has the following characteristics: generally formed in still water or slow-flowing water environment (such as water accumulation pit, marsh, depression, etc.), composed of fine-grained clay, silt and organic matter deposited for a long time, natural porosity ratio is usually >1.5, organic matter content ≥5%. High natural water content, liquid limit >50%, plastic limit index >20, low permeability coefficient, small specific gravity. Very low shear strength, high compressibility, significant rheological property, thixotropy. Foundation bearing capacity is insufficient, post-construction settlement is large and uneven, drainage consolidation time is long, and construction disturbance easily causes soil instability.

[0003] Traditional silt foundation treatment often uses replacement method, preloading method or pile foundation reinforcement. Replacement method is suitable for the case where silt layer is relatively thin, and silt layer is replaced with sandy loam soil, lime soil, coarse sand and cement soil to treat the foundation; preloading method uses sand well, sand well preloading, electro-osmosis method, etc. to promote soil layer drainage consolidation to improve foundation bearing capacity; when silt layer is thick, it is difficult to perform deep treatment on a large area, and piling method can be used for reinforcement treatment. These traditional methods have the following defects: large material consumption and high cost when treating on a large area, poor economy; long drainage consolidation period (3-6 months); pile foundation construction destroys the original soil structure; uneven post-construction settlement caused by uneven local bearing capacity. UTILITY MODEL CONTENTS

[0004] The utility model aims at the problems of high construction cost, long construction period, large material consumption and uneven local bearing capacity in existing silt foundation treatment technology, and provides a seepage drainage reinforcement structure for large-area silt foundation treatment construction.

[0005] To achieve the above purpose of the utility model, the seepage drainage reinforcement structure for large-area silt foundation treatment construction adopts the following technical scheme:

[0006] The utility model discloses a seepage drainage reinforcing structure for large-area silt foundation treatment construction, which is characterized by being composed of gravel soil material partition dam, soil blind ditch, soil grid, water collection pool, water collection well, lifting pump and external drainage pipe.

[0007] Preferably, the top surface width of the gravel soil material partition dam is not less than 3m, and the slope ratio is controlled between 1:1.5 and 1:2.0.

[0008] Preferably, the dam top elevation of the gravel soil material partition dam is controlled at 1.3-1.6m higher than the silt foundation (8), which comprehensively considers the vertical deformation reserve of soil consolidation compression and ensures the operation safety during the mud extrusion and upward process.

[0009] Preferably, the soil blind ditch is wrapped with 160-250g / m 2 long filament geotextile.

[0010] Preferably, the soil grid adopts U-shaped buckle, and the longitudinal overlap length is greater than or equal to 300mm, and the transverse overlap length is greater than or equal to 200mm.

[0011] Preferably, the soil grid adopts biaxially oriented polypropylene soil grid.

[0012] Preferably, the water permeable pipe laid at the bottom of the soil blind ditch adopts soft water permeable pipe with DN75-DN100.

[0013] Experimental research and application results show that the drainage and reinforcement structure of this utility model for the treatment of large-area silt foundations, after adopting the above technical solution, has the following positive effects: When treating large-area silt foundations, the use of a partitioned dam method shortens the treatment cycle by more than 40% (the measured average consolidation is completed in 28 days), reduces the overall cost by more than 65% (compared to the traditional pile foundation scheme), and increases the foundation bearing capacity to more than 150 kPa. Through grid-based zoning, differential settlement is effectively controlled, effectively solving the problems of high cost, long cycle, low foundation bearing capacity, and difficulty in using traditional silt foundation treatment methods for large-area silt foundations, achieving unexpected technical and economic benefits. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the plan layout of a drainage and reinforcement structure for large-area silt foundation treatment construction according to the present invention.

[0015] Figure 2 A cross-sectional view of the internal structure of the dam designed for this utility model.

[0016] Attached diagram labels: 1-Gravel and soil separating dam; 2-Geotechnical blind ditch; 3-Geogrid; 4-Catching pool; 5-Collection well; 6-Lift pump; 6'-External drainage pipe; 7-Loess layer; 8-Silt foundation. Detailed Implementation

[0017] To further describe this utility model, the following detailed description of the drainage and reinforcement structure for large-area silt foundation treatment construction is provided in conjunction with the accompanying drawings.

[0018] Depend on Figure 1 The diagram shown is a schematic representation of the plan layout of a drainage and reinforcement structure for the treatment of large-area silt foundations, based on the present invention. Figure 2It can be seen that a seepage drainage and reinforcement structure for large-area silt foundation treatment of the present utility model is composed of a gravel soil separator dam 1, a geocomposite drain 2, a geogrid 3, a sump 4, a catch well 5, a lift pump 6, and an external drain pipe 6'. The gravel soil separator dam 1 is arranged on the silt foundation 8 in a "field" - shaped grid, forming a crisscross "field" - shaped structure. The geocomposite drain 2 is arranged at the middle and lower part of the gravel soil separator dam 1. The cross - section of the geocomposite drain 2 is trapezoidal. A permeable pipe with a diameter of Φ75 - 100mm is laid at the bottom of the geocomposite drain 2, and the longitudinal slope is ≥0.5%. The catch well 5 is arranged in the geocomposite drain 2 at the intersection of the gravel soil separator dams 1, and the distance between adjacent catch wells 5 is 40 - 60m. The sump 4 is arranged at the low - lying area of the silt foundation 8, and the sump 4 is connected to the permeable pipe laid at the bottom of the geocomposite drain 2. The lift pump 6 is located in the sump 4, and the drainage outlet of the lift pump 6 is connected to the external drain pipe 6'. In the embodiment, a seepage drainage and reinforcement structure for large - area silt foundation treatment of the present utility model is implemented by the following steps:

[0019] S1 Zoning and Enclosure: On the silt foundation 8, the treatment area is divided into a "field" - shaped grid, and the grid unit size is controlled within 20m×20m. A crawler excavator is used to fill and construct a trapezoidal cross - section working platform with gravel soil on the "field" - shaped grid, and the backfilled and compacted gravel soil forms a crisscross "field" - shaped gravel soil separator dam 1. The top width of the gravel soil separator dam 1 is not less than 3m, and the slope ratio of the slope is controlled between 1:1.5 and 1:2.0, ensuring that it meets the requirements for heavy machinery to pass and operate. The top elevation of the gravel soil separator dam 1 is controlled to be 1.5m higher than the surface of the silt foundation 8. This elevation design comprehensively considers the vertical deformation caused by soil consolidation and compression and reserves enough buffer space, while ensuring the operation safety during the process of mud extrusion and up - turning during construction.

[0020] S2 Drainage System Setting: After the "field" - shaped gravel soil separator dam 1 is built, a trapezoidal cross - section geocomposite drain 2 is set along the middle and lower part of the gravel soil separator dam 1. A DN75 - DN100 soft permeable pipe made of high - density polyethylene is laid at the bottom of the geocomposite drain 2, and the longitudinal slope of the permeable pipe is ≥0.5%. Every 40 - 60m, a catch well 5 is set in the geocomposite drain 2 at the intersection of the gravel soil separator dams 1. The geocomposite drain 2, the permeable pipe, and the catch well 5 jointly form a drainage system. The permeable pipe is wrapped with 200g / m 2 long - filament geotextile (meeting the GB / T17639 standard).

[0021] S3 Sump Pool Setup: Considering the elevation characteristics of the site where the silt foundation 8 is located, a sump pool 4 is selected and constructed. The sump pool 4 is connected to the permeable pipes laid at the bottom of the geocomposite drain 2. A lift pump 6 is installed in the sump pool 4, and the drainage outlet of the lift pump 6 is connected to the external drainage pipe 6' to drain the water flowing into the sump pool 4 to the outside.

[0022] S4 Consolidation Control: Through the combined drainage of the gravel soil separator dam 1, the geocomposite drain 2, the permeable pipes laid at the bottom, and the sump pool 4, subsequent construction is carried out after the moisture content of the silt drops below 45%.

[0023] S5 Reinforcement Treatment: After the moisture content of the silt drops below 45%, geogrid 3 (TGDG80 type) is laid in layers on the surface of the silt foundation 8. The laying directions of adjacent layers are orthogonal, and the single-layer tensile strength is ≥80 kN / m. The geogrid 3 uses U-shaped fasteners, with a longitudinal lap length of ≥300 mm and a transverse lap length of ≥200 mm. The geogrid 3 uses a biaxially oriented polypropylene geogrid, and its longitudinal and transverse tensile strengths are both ≥80 kN / m.

[0024] S6 Consolidation and Hardening: Loess is backfilled on the geogrid 3 laid in the "field" - shaped grid of the silt foundation 8 to the top elevation of the gravel soil separator dam 1 to form a loess layer 7, squeezing the moisture of the lower silt layer and enhancing the bearing capacity of the silt foundation 8.

[0025] The utility model has been applied in the construction of a large - area silt foundation treatment. Compared with the traditional pile foundation reinforcement method, consolidation is completed in an average of 28 days, the treatment period is shortened by more than 40%, the comprehensive cost is reduced by more than 65%, and the foundation bearing capacity is increased to more than 150 kPa.

Claims

1. A drainage and reinforcement structure for large-area treatment of silt ground, characterized by: It is composed of a gravel-soil separating dam (1), a geogrid (2), a geogrid (3), a catchment pool (4), a collection well (5), a booster pump (6), and an external drainage pipe (6'). The gravel-soil separating dam (1) is laid on the silt foundation (8) in a grid pattern, forming a crisscrossing grid structure. The geogrid (2) is located in the middle and lower part of the gravel-soil separating dam (1). The cross-section of the geogrid (2) is trapezoidal. The bottom of the geogrid (2) is laid with... The permeable pipe has a diameter of 75-100mm and a longitudinal slope of ≥0.5%. The water collection well (5) is set in the geotechnical blind ditch (2) at the junction of the gravel and soil separating dam (1), and the distance between adjacent water collection wells (5) is 40-60m. The water collection pool (4) is set in the low-lying area of ​​the silt foundation (8), and the water collection pool (4) is connected to the permeable pipe laid at the bottom of the geotechnical blind ditch (2). The lifting pump (6) is located in the water collection pool (4), and the drain outlet of the lifting pump (6) is connected to the external drain pipe (6').

2. The drainage and reinforcement structure for large-area mucky ground treatment construction according to claim 1, characterized in that: The top width of the crushed stone and soil separating dam (1) is not less than 3m, and the slope ratio is controlled between 1:1.5 and 1:2.

0.

3. The drainage and reinforcement structure for large-area mucky ground treatment construction according to claim 1, characterized in that: The top elevation of the gravel-soil separating dam (1) is controlled to be 1.3 to 1.6 m above the silt foundation (8).

4. The drainage and reinforcement structure for large-area mucky ground treatment construction according to claim 1, characterized in that: The earthwork blind drain (2) is wrapped with 160-250 g / m 2 of filament earthwork cloth.

5. The drainage and reinforcement structure for large-area muck ground treatment construction according to Claim 1, characterized by: The geogrid (3) uses U-shaped buckles with a longitudinal overlap length ≥300mm and a transverse overlap length ≥200mm.

6. The drainage and reinforcement structure for large-area treatment of silt ground according to claim 1, 2, 3, 4 or 5, characterized in that: The geogrid (3) mentioned above is a biaxially oriented polypropylene geogrid.

7. The drainage and reinforcement structure for large-area muck ground treatment construction according to claim 6, characterized in that: The permeable pipes laid at the bottom of the geotechnical blind ditch (2) are DN75-DN100 flexible permeable pipes.

8. The drainage and reinforcement structure for large-area mucky ground treatment construction according to claim 2, characterized in that: The dam top elevation of the gravel soil material partition dam (1) is controlled at 1.3-1.6 m higher than the silt foundation (8); the outer package of the soil blind ditch (2) is 160-250 g / m 2 of the filiform geotextile; the soil grillage (3) adopts U-shaped buckle, the longitudinal lap length is greater than or equal to 300 mm, and the transverse lap length is greater than or equal to 200 mm; the soil grillage (3) adopts bidirectional tensile polypropylene soil grillage; the water permeable pipe laid at the bottom of the soil blind ditch (2) adopts soft water permeable pipe with DN75-DN100.

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