Sluggy soil deep foundation pit excavation structure based on combination of steel sheet piles and in-situ solidification

Abstract

The utility model discloses a mucky soil deep foundation pit excavation structure based on combination of steel sheet piles and in-situ solidification, which comprises an original ground line, the original ground line is downwards provided with three step excavation areas, the three step excavation areas are vertically formed in a layered mode, the central axes of the three step excavation areas are located on the same straight line, and the three step excavation areas are arranged on the same straight line. The areas of the three step excavation areas are gradually increased from bottom to top, the step parts of the three step excavation areas have the same step part shape, the area differences of the adjacent step parts are the same, steel sheet piles are arranged in the three step excavation areas, and soil in the range of the steel sheet piles is solidified. The problems that an existing deep foundation pit excavation structure is low in strength and large in construction difficulty are solved, the construction safety is improved seriously, and the project progress is accelerated.

Description

Technical Field

[0001] The utility model belongs to the technical field of hydraulic engineering in water conservancy projects and relates to a silty soil deep foundation pit excavation structure based on a combination of steel sheet piles and in-situ solidification. Background Art

[0002] Deep foundation pit excavation is an important project in water conservancy projects. The construction safety of deep foundation pits is of vital importance. Improper construction operations can easily cause the horizontal displacement and settlement of ground buildings to exceed the safe distance, posing a major safety hazard.

[0003] Muddy soil has the characteristics of low liquid limit, low permeability, and difficulty in drainage and consolidation. It also has certain rheological properties and easily liquefies into silt when in contact with water, which affects foundation pit excavation. Especially in the rainy season, continuous rain makes the bottom of the foundation pit full of silt. Muddy soil has a high water content and low bearing capacity. It is often difficult to carry out deep foundation pit excavation on it, especially for deep foundation pits within the depth range of 10-15 meters. It is more difficult to treat, which seriously affects the progress of foundation pit soil excavation. Common treatment methods include pile foundation method, soil replacement method, cement mixing method, caisson foundation method, etc. These methods often have high investment, long construction period, and complex process. At the same time, during the excavation of deep foundation pits, the slopes are prone to collapse, groundwater leakage occurs, and affects operations; if the foundation pit is not treated properly, the slopes are prone to collapse and damage, posing a safety threat to workers and buildings in the foundation pit, affecting project safety.

[0004] Existing deep foundation pit excavation structures need to install support brackets inside them before excavation to improve the strength of the structure. Support is provided while excavation is carried out. As the excavation goes deeper, more and more parts of the excavated structure are exposed. The support brackets gradually become only able to support the upper half of the structure. The excavated part has no supporting structure, has low strength, and is difficult to construct. Therefore, for deep foundation pit excavation in silty soil, choosing a suitable treatment method is the key to ensuring the safety of engineering construction. Utility Model Content

[0005] The purpose of the utility model is to provide a silty soil deep foundation pit excavation structure based on a combination of steel sheet piles and in-situ solidification, which solves the problems of low strength and great construction difficulty in existing deep foundation pit excavation structures.

[0006] The technical solution adopted by the present invention is a silty soil deep foundation pit excavation structure based on a combination of steel sheet piles and in-situ solidification, including an original ground line, three stepped excavation areas are arranged downward from the original ground line, the three stepped excavation areas are formed in vertical layers, the central axes of the three stepped excavation areas are on the same straight line, the areas of the three stepped excavation areas gradually increase from bottom to top, the steps of the three stepped excavation areas have the same step shape, the area difference of adjacent steps is the same, steel sheet piles are arranged in the three stepped excavation areas, and solidification treatment is adopted for the soil within the range of the steel sheet piles.

[0007] The utility model is also characterized in that:

[0008] The three step excavation areas include the third step excavation area, the second step excavation area, and the first step excavation area, which are arranged from bottom to top. Excavation is carried out from the center of the third step excavation area to the surrounding areas. The top of the first step excavation area is flush with the original ground line.

[0009] Several third-step steel sheet piles are arranged around the third-step excavation area, and the third-step steel sheet piles are tightly connected to form a closed enclosure structure; several second-step steel sheet piles are arranged around the second-step excavation area, and the second-step steel sheet piles are tightly connected to form a closed enclosure structure; several first-step steel sheet piles are arranged around the first-step excavation area, and the first-step steel sheet piles are tightly connected to form a closed enclosure structure

[0010] The shape of the enclosing structure can be square or circular.

[0011] The silt inside the closed enclosure structure was solidified and then excavated to a depth of 6m.

[0012] The third step steel sheet piles, the second step steel sheet piles and the first step steel sheet piles are 15m deep Larsen steel sheet piles. The minimum depth of the Larsen steel sheet piles buried in the silt is 9m, and the part exposed above the ground is m.

[0013] The bottom of the third step excavation area is solidified to a depth of 1m-2m to form a solidification working platform for the bottom layer of the foundation pit.

[0014] The second step soil solidification platform is formed between the outer periphery of the top of the third step steel sheet pile and the inner wall of the second step steel sheet pile. The first step soil solidification platform is formed between the outer periphery of the top of the second step steel sheet pile and the inner wall of the first step steel sheet pile. The width of the first step soil solidification platform and the second step soil solidification platform are both 3m.

[0015] The beneficial effects of the present invention are as follows: the present invention is based on a silty soil deep foundation pit excavation structure of a combination of steel sheet piles and in-situ solidification, and adopts a soil solidifier and steel sheet pile combination treatment method to carry out a structure for deep foundation pit silt excavation treatment, thereby ensuring construction safety, forming an overall support system more quickly, reducing the construction operation risks and construction difficulties of silty soil deep foundation pits, effectively improving construction efficiency, ensuring overall strength and water isolation effect, and ensuring project progress. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the excavation structure of a deep foundation pit in silty soil based on a combination of steel sheet piles and in-situ solidification in the utility model;

[0017] Figure 2 This is a schematic diagram of the step-by-step solidification of a deep foundation pit according to the present invention;

[0018] Figure 3 It is a schematic diagram of step-by-step solidified soil excavation for a deep foundation pit according to the present invention.

[0019] In the figure, 1. Original ground line, 2. First step steel sheet piles, 3. Second step steel sheet piles, 4. Third step steel sheet piles, 5. First step soil solidification platform, 6. Second step soil solidification platform, 7. Foundation pit bottom solidification working platform. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0021] Example 1

[0022] The utility model is based on the silty soil deep foundation pit excavation structure of the steel sheet pile and in-situ solidification combination. Figure 1 、 Figure 2 、 Figure 3 As shown, it includes the original ground line 1, and three step excavation areas are set downward from the original ground line 1. The three step excavation areas are formed in vertical layers, and the central axes of the three step excavation areas are on the same straight line. The areas of the three step excavation areas gradually increase from bottom to top, and the steps between the three step excavation areas have the same step shape, and the area difference between adjacent steps is the same. Steel sheet piles are set in the three step excavation areas, and the steel sheet piles are used to protect the slopes of the three step excavation areas respectively. The steel sheet piles have high strength and high safety; the soil within the range of the steel sheet piles is solidified, the construction process is simple, and the on-site construction is convenient; the steel sheet piles are combined with the solidified soil technology, and the anti-seepage performance of the slope is significantly improved, which effectively reduces the seepage of the foundation pit.

[0023] Example 2

[0024] The utility model is based on a silty soil deep foundation pit excavation structure of a combination of steel sheet piles and in-situ solidification, comprising an original ground line 1, three step excavation areas are arranged downward from the original ground line 1, the three step excavation areas are formed in vertical layers, the central axes of the three step excavation areas are on the same straight line, the areas of the three step excavation areas gradually increase from bottom to top, the steps of the three step excavation areas have the same step shape, the area difference between adjacent steps is the same, steel sheet piles are arranged in the three step excavation areas, and on the basis of Example 1, the three step excavation areas include a third step excavation area, a second step excavation area, and a first step excavation area arranged in sequence from bottom to top, and excavation is carried out from the center of the third step excavation area to the surrounding areas, and the top of the first step excavation area is flush with the original ground line 1.

[0025] Example 3

[0026] The utility model is based on a silty soil deep foundation pit excavation structure of a combination of steel sheet piles and in-situ solidification, comprising an original ground line 1, three step excavation areas are arranged downward from the original ground line 1, the three step excavation areas are formed in vertical layers, the central axes of the three step excavation areas are on the same straight line, the areas of the three step excavation areas gradually increase from bottom to top, the step portions of the three step excavation areas have the same step portion shape, the area difference between adjacent step portions is the same, steel sheet piles are arranged in the three step excavation areas, the three step excavation areas comprise a third step excavation area, a second step excavation area, and a first step excavation area which are arranged in sequence from bottom to top, excavation is carried out from the center of the third step excavation area to the surrounding areas, and the top of the first step excavation area is flush with the original ground line 1. On the basis of Example 2, a number of third step steel sheet piles 4 are arranged in the circumference of the third step excavation area, and the third step steel sheet piles 4 are tightly connected to form a closed enclosure structure, and the shape of the enclosure structure is square or circular; a number of second step steel sheet piles 3 are arranged in the circumference of the second step excavation area, and the second step steel sheet piles 3 are tightly connected to form a closed enclosure structure, and the shape of the enclosure structure is square or circular; a number of first step steel sheet piles 2 are arranged in the circumference of the first step excavation area, and the first step steel sheet piles 2 are tightly connected to form a closed enclosure structure, and the shape of the enclosure structure is square or circular.

[0027] On the basis of Example 3, the silt inside the closed enclosure structure was solidified and then excavated to a depth of 6 m.

[0028] The solidification treatment uses soil solidifier. The amount of soil solidifier used is selected according to the moisture content of the silt soil and the type of silt, and the addition ratio is 10%-12%.

[0029] The third step steel sheet piles 4, the second step steel sheet piles 3, and the first step steel sheet piles 2 are 15m deep Larsen steel sheet piles. The minimum depth of the Larsen steel sheet piles buried in the silt is 9m, and the part exposed above the ground is 6m.

[0030] The bottom of the third step excavation area is solidified to a depth of 1m-2m to form a foundation pit bottom solidification working platform 7.

[0031] A second step soil solidification platform 6 is formed between the top periphery of the third step steel sheet pile 4 and the inner wall of the second step steel sheet pile 3, and a first step soil solidification platform 5 is formed between the top periphery of the second step steel sheet pile 3 and the inner wall of the first step steel sheet pile 2. The width of the first step soil solidification platform 5 and the second step soil solidification platform 6 are both 3m.

[0032] The working principle of this utility model's deep foundation pit excavation structure for silty soil, based on a combination of steel sheet piles and in-situ solidification, is as follows: Step-by-step layered excavation is adopted to reduce disturbance to the slope. The steel sheet piles are combined with soil solidification technology to ensure the firmness of the steel sheet pile connection in the silt soil, improving overall stability. The silt soil between the steel pipe piles is solidified and stabilized, ensuring the embedding effect of the silt soil and keeping the steel sheet piles in a stable state, thereby achieving rapid foundation pit support construction under silt soil conditions. The anti-seepage performance of the foundation pit slope is significantly improved, effectively reducing foundation pit seepage. Solidification treatment is applied to the soil within the steel sheet pile range, improving the integrity and strength of the excavation structure, and ensuring construction safety and project progress.

[0033] The working process of the silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification of the utility model is as follows: after steel sheet piles are used to enclose the silt in steps, soil solidifier is added to the silt inside the enclosed area, and the silt in the deep foundation pit is solidified in situ. After the solidification treatment, the soil in the foundation pit is excavated. After the excavation is completed, steel sheet piles and solidified soil are used as retaining structures to finally form a silty soil deep foundation pit working environment, providing a site for the next step of construction work. Solidification and excavation are both carried out in a step-by-step manner.

[0034] When solidifying the silt in steps, the foundation pit solidification range is divided into three steps according to the number of steel sheet pile layers. The three steps are the third step, the second step, and the first step from bottom to top. Each layer of the three steps is 4-6m deep. The step at the bottom is 3m smaller than the outer contour of the upper step above, and serves as a solidification work platform.

[0035] When excavating the solidified soil, after the silty soil foundation has solidified in situ for seven days and meets the design strength, an excavator is used to excavate the solidified soil in the foundation pit as required. The abandoned soil is transported off-site by vehicles, and excavation is carried out from the third step excavation area as the center of the foundation pit to the surrounding areas. The soil solidifier is used in a step-by-step solidification method, from top to bottom. The soil solidifier is delivered to the site working surface by a delivery pump, and the in-situ soil is vertically stirred up and down using an appropriate strong mixing head.

[0036] When approaching the steel sheet piles of the foundation pit, the steel sheet piles must not be damaged. The solidified soil treatment method must strictly follow the step-by-step solidification and excavation method. After the previous step is completed, the next step can be carried out.

[0037] Soil solidification work platform at the bottom of the foundation pit: To form a work platform at the bottom of the foundation pit, it is convenient for drilling holes or mechanical operations on the building foundation. The solidification method is the same.

[0038] The utility model discloses a deep foundation pit excavation structure for silty soil based on a combination of steel sheet piles and in-situ solidification, forms a deep foundation pit excavation with layers and segments, improves construction progress and reduces safety risks; increases the overall stability of the structure, ensures the normal progress of deep foundation pit excavation, improves soil excavation efficiency, and can also carry out foundation pit excavation in low-permeability silt soil without precipitation, reduces soil quality requirements, has a wide range of applications, improves the excavation efficiency of silt soil in the rainy season, is convenient and quick to construct, is conducive to saving construction period and cost, and has great social and economic benefits.

Claims

1. A deep foundation pit excavation structure for muddy soil based on a combination of steel sheet piles and in-situ solidification, characterized in that: The invention comprises an original ground line (1), three step excavation areas are set downward from the original ground line (1), the three step excavation areas are formed in vertical layers, the central axes of the three step excavation areas are on the same straight line, the areas of the three step excavation areas gradually increase from bottom to top, the step portions of the three step excavation areas have the same step portion shape, the area difference of adjacent step portions is the same, steel sheet piles are set in the three step excavation areas, and the soil within the range of the steel sheet piles is solidified.

2. The silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification according to claim 1 is characterized in that: The three step excavation areas include a third step excavation area, a second step excavation area, and a first step excavation area, which are arranged in sequence from bottom to top. Excavation is carried out from the center of the third step excavation area to the surrounding areas. The top of the first step excavation area is flush with the original ground line (1).

3. The silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification according to claim 2 is characterized in that: A plurality of third step steel sheet piles (4) are arranged in a circumferential direction of the third step excavation area, and the plurality of third step steel sheet piles (4) are tightly connected to form a closed enclosure structure; a plurality of second step steel sheet piles (3) are arranged in a circumferential direction of the second step excavation area, and the plurality of second step steel sheet piles (3) are tightly connected to form a closed enclosure structure; a plurality of first step steel sheet piles (2) are arranged in a circumferential direction of the first step excavation area, and the plurality of first step steel sheet piles (2) are tightly connected to form a closed enclosure structure.

4. The silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification according to claim 3 is characterized in that: The shape of the closed enclosure structure is square or circular.

5. The silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification according to claim 3 is characterized in that: The internal silt of the closed enclosure structure is solidified and then excavated to a depth of 6m.

6. The silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification according to claim 3 is characterized in that: The third step steel sheet piles (4), the second step steel sheet piles (3), and the first step steel sheet piles (2) are 15m deep Larsen steel sheet piles. The minimum depth of the Larsen steel sheet piles buried in the mud is 9m, and the part exposed above the ground is 6m.

7. The silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification according to claim 2 is characterized in that: The bottom of the third step excavation area is solidified to a depth of 1m-2m to form a foundation pit bottom solidification operation platform (7).

8. The silty soil deep foundation pit excavation structure based on the combination of steel sheet piles and in-situ solidification according to claim 3 is characterized in that: A second step soil solidification platform (6) is formed between the outer periphery of the top of the third step steel sheet pile (4) and the inner wall of the second step steel sheet pile (3), and a first step soil solidification platform (5) is formed between the outer periphery of the top of the second step steel sheet pile (3) and the inner wall of the first step steel sheet pile (2). The width of the first step soil solidification platform (5) and the second step soil solidification platform (6) are both 3m.

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