Wallboard combined composite foundation reinforcing super large silt deep foundation pit structure and construction method

Abstract

The application discloses a structure and a construction method for reinforcing an ultra-large silt deep foundation pit by a wallboard combined composite foundation, and the construction of a diaphragm wall and a vertical reinforcing body around the foundation pit is performed before on-site excavation of the foundation pit; in the subsequent excavation process, the excavation is performed in a manner of supporting first and then digging, layer-by-layer excavation and symmetrical excavation; after the excavation reaches the foundation, a high-pressure rotary jet grouting pile method is used to perform transverse reinforcement of soil, and the vertical reinforcing body and each adjacent transverse reinforced area are connected, so that a reinforced plate with a certain thickness in the horizontal direction is finally formed; and in combination with a mixing pile, the stability and strength of the soil in the vertical direction can be greatly improved, and soil settlement is reduced.

Description

Technical Field

[0001] This invention belongs to the field of building construction and foundation pit construction, and particularly relates to a structure and construction method for reinforcing ultra-large silt deep foundation pits with a composite foundation of wall panels. Background Technology

[0002] In building construction and foundation pit engineering, due to land use restrictions and railway planning, foundation pits are often excavated in areas rich in silt soil, and various types of housing and stations are built on top. However, with the increase of the superstructure load and inadequate treatment of the weak foundation strata, uneven settlement of the foundation occurs during later use, leading to damage to the building's foundation slab and structure, resulting in loss of life and property. Therefore, how to effectively and efficiently reinforce weak silt foundations has become a key focus of foundation engineering. Summary of the Invention

[0003] Traditional construction methods for soft soil foundation treatment in building construction and foundation pit engineering typically include methods such as replacement, dynamic compaction, composite foundations, and vacuum combined surcharge preloading. These methods generally suffer from drawbacks such as numerous procedures, long construction periods, and poor stability, and are also limited by on-site construction site and machinery conditions. To address these issues, this invention provides a structure and construction method for reinforcing ultra-large silt-filled deep foundation pits using a composite foundation with wall panels. This method features a simple structure, convenient on-site construction, and is beneficial for improving the strength of soft soil foundations and ensuring the long-term normal operation of buildings.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a structure for reinforcing ultra-large silt deep foundation pits with a combined wall panel and composite foundation, including a diaphragm wall, a vertical reinforcement body, a horizontal reinforcement area of ​​a single jet grouting pile, a base, foundation pit soil, a wall panel and a cushion layer. The diaphragm wall is set around the base, the vertical reinforcement body is set inside the foundation pit, the vertical reinforcement body is connected in the middle by a horizontal reinforcement area of ​​a high-pressure jet grouting pile, and the horizontal reinforcement areas of adjacent single jet grouting piles are connected to form a wall panel. The vertical reinforcement body is connected below the base and the cushion layer is connected above the base.

[0005] Furthermore, the wall panel is provided with one or two layers.

[0006] Furthermore, the vertical reinforcement body is a reinforcement body that can form a vertical strip in the soil, including foundation treatment forms such as mixing piles, jet grouting piles, grouting reinforcement, and compaction reinforcement.

[0007] The present invention discloses a construction method for a structure for reinforcing ultra-large silt deep foundation pits using a composite foundation combined with wall panels, comprising the following steps:

[0008] (1) Construction of diaphragm walls and vertical reinforcements around the foundation pit: Level the site, surveyors lay out the diaphragm wall axis position according to the coordinates, carry out the construction of the guide wall, then mix mud slurry for mud slurry wall protection, use grab bucket to form diaphragm wall trench, use lock pipe to form semi-recessed tenon joint, carry out diaphragm wall section joint treatment, and construct vertical reinforcements.

[0009] (2) Excavation of the foundation pit: After the diaphragm wall and the vertical reinforcement body have reached the strength, the foundation pit is excavated. During the excavation process, the foundation is supported before excavation, the water is dewatered before excavation, and the excavation is carried out in layers, zones, and symmetrically.

[0010] (3) Lateral reinforcement of soil: After excavation to the foundation, the high-pressure jet grouting pile positions are marked on the foundation surface and the high-pressure jet grouting piles are constructed. After the construction of a single jet grouting pile lateral reinforcement area is completed, it is connected with other reinforcement areas to form a whole and form a wall panel.

[0011] (4) Inspection: After the wall panel construction is completed, steel plates are driven into the joint to check whether the joint is in place. If it is not in place, jet grouting piles are carried out again at the joint as a reinforcement measure.

[0012] (5) Subbase construction: After the wall panel construction is completed and passes inspection, the base subbase or bottom plate is constructed, and then the superstructure is constructed.

[0013] This invention involves constructing diaphragm walls and vertical reinforcement structures around the foundation pit before excavation. During subsequent excavation, the process follows a principle of supporting the soil before excavation, layered excavation, and symmetrical excavation. After excavating to the foundation, high-pressure jet grouting is used to horizontally reinforce the soil and connect the vertical reinforcement structures with adjacent horizontally reinforced areas, ultimately forming a reinforced plate of a certain thickness in the horizontal direction. Combined with soil mixing piles, this significantly improves the vertical stability and strength of the soil, reducing soil settlement.

[0014] As the composite foundation reinforcement structure and construction method of the wall panel of the present invention, the vertical reinforcement body in the soil is not limited to foundation treatment methods such as mixing piles, jet grouting piles, grouting reinforcement, and compaction reinforcement. As long as a vertical strip-shaped reinforcement body can be formed in the soil, the requirements can be met.

[0015] As the composite foundation reinforcement structure and construction method of the wall panel of the present invention, the spacing and depth of the vertical reinforcement should be determined according to the project scale. The spacing is generally not greater than the working distance of the high-pressure jet grouting pile in the horizontal direction, so as to facilitate the overlap of each horizontal reinforcement area in the later stage.

[0016] As the composite foundation reinforcement structure and construction method of the wall panel of the present invention, the high-pressure jet grouting pile method can achieve reinforcement in various directions in the soil, can effectively control the reinforcement area and reinforcement depth in the soil, and achieves economical use of materials.

[0017] As the wall panel combined composite foundation reinforcement structure and its construction method of the present invention, after the vertical reinforcement body and the horizontal reinforcement area are connected together, the vertical bearing capacity of the vertical reinforcement body can be greatly improved by the integrity of the horizontal reinforcement area, and the settlement of the top of the reinforcement body can be reduced. At the same time, the horizontal reinforcement area also restricts the vertical settlement of the soil due to the restrictive effect of the vertical reinforcement body in the soil, and improves the integrity of the reinforcement area.

[0018] As the composite foundation reinforcement structure and construction method of the present invention, the base adopts high-pressure jet grouting piles to form a reinforced whole, similar to full-span reinforcement, and is combined with the diaphragm wall on all sides, which can greatly improve the ability of the passive zone of the soil at the bottom of the foundation pit to resist deformation and limit the horizontal and vertical displacement of the diaphragm wall.

[0019] The advantages of this invention are as follows:

[0020] 1) Vertical reinforcement can take many forms, and different construction techniques can be adopted according to the site conditions and design depth to achieve localized, economical and efficient results.

[0021] 2) High-pressure jet grouting pile technology is mature and reliable. The stability and strength of the soil treated by high-pressure jet grouting piles are significantly improved.

[0022] 3) High-pressure jet grouting piles have all-round reinforcement characteristics, which can meet the generation of lateral reinforcement areas and ensure the overlap and connection between the reinforcement areas of each high-pressure jet grouting pile point.

[0023] 4) Vertical reinforcement can reduce vertical settlement of soil, while horizontal reinforcement can reduce uneven settlement of soil. The combination of the two can significantly reduce the settlement and uneven settlement of the base plate, ensuring the safety of the superstructure. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of this invention, the accompanying drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure;

[0026] Figure 2 A schematic diagram of the reinforcement zone for a single jet grouting pile location;

[0027] Figure 3 This is a schematic diagram of a single-layer wall panel structure;

[0028] Figure 4 This is a schematic diagram of a double-layer wall panel structure;

[0029] Figure 5 This is a schematic diagram of a vertically reinforced body.

[0030] Figure 6 This is a schematic diagram of the cross-section of the structure;

[0031] Figure 7 This is a schematic diagram of the longitudinal section of the structure;

[0032] Figure 8 This is a schematic diagram of the wall panel in the soil.

[0033] The meanings of the symbols marked in the figure are as follows:

[0034] 1. Diaphragm wall 2. Vertical reinforcement body 3. Horizontal reinforcement area of ​​a single jet grouting pile 4. High-pressure jet grouting pile location 5. Foundation 6. Excavation pit soil 7. Wall panel 8. Cushion layer. Detailed Implementation

[0035] This invention provides a structure for reinforcing ultra-large silt-filled deep foundation pits using a combined wall panel and composite foundation. The invention is further described below with reference to embodiments. The descriptions of the embodiments below are merely for the purpose of helping to understand the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this invention.

[0036] like Figure 1-8 As shown in the preferred embodiment of the present invention, the specific construction method of the structure for reinforcing ultra-large silt deep foundation pits with wall panels combined with composite foundations is as follows:

[0037] 1. Level the site, and surveyors will mark the axis position of the diaphragm wall 1 according to the coordinates. Construction of the guide wall will then commence. Mud slurry will be prepared for wall protection, and a grab bucket will be used to create the trench for the diaphragm wall. A semi-recessed tenon joint will be formed using a locking pipe for joint treatment of the diaphragm wall segments.

[0038] 2. Vertical reinforcement system 2: Taking cement mixing pile as an example. The construction steps are as follows: pile location layout → drilling rig positioning → inspection and adjustment of drilling rig → forward circulation drilling to the design depth → turning on the high-pressure grouting pump → reverse circulation drilling and spraying cement slurry → to 0.3m below the working reference surface → repeated mixing and drilling down to the design depth → reverse circulation drilling and spraying cement slurry to the ground surface → pile completion → construction of the next pile.

[0039] 3. After the diaphragm wall and cement mixing piles have reached the required strength, the foundation pit excavation work shall be carried out. During the excavation process, the following should be done: support before excavation, dewatering before excavation, layered excavation, zoned excavation, and symmetrical excavation.

[0040] 4. After excavation to the foundation, mark the high-pressure jet grouting pile locations (4) on the foundation surface and begin high-pressure jet grouting pile (3) construction. The depth and location of the high-pressure jet grouting piles should be determined based on the effective radius of the high-pressure jet grouting pile construction operation to ensure proper overlap of all lateral reinforcement areas. The high-pressure jet grouting pile construction steps are: pile location determination → drilling → grout control → hole acceptance → grout injection → inspection of overlap areas.

[0041] 5. After the construction of a single jet grouting pile's lateral reinforcement area is completed, it is connected with other reinforcement areas to form a whole, forming wall panel 7. Depending on the silt depth and bearing capacity, one or two layers of wall panels need to be constructed. The intervals between the lateral reinforcement areas of a single jet grouting pile should not be too far to ensure complete overlap, so as to form a more integral 'jet grouting pile panel'.

[0042] 6. After the wall panel construction is completed, steel plates can be driven into the overlap to check whether the overlap is in place. If it is not in place, jet grouting piles should be installed again at the overlap as a reinforcement measure.

[0043] 7. After the wall panel 7 is completed and passes inspection, the base layer 8 or the bottom plate is constructed, and then the upper structure is constructed.

[0044] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

Claims

1. A structure for reinforcing ultra-large silt-filled deep foundation pits using a combination of wall panels and composite foundation, characterized in that, The structure includes a diaphragm wall, a vertical reinforced body, a horizontally reinforced area of ​​a single jet grouting pile, a foundation, excavation soil, a wall panel, and a cushion layer. A diaphragm wall is installed around the perimeter of the foundation. A vertical reinforced body is installed within the excavation pit. The vertical reinforced bodies are connected in the middle by horizontally reinforced areas of high-pressure jet grouting piles. Adjacent horizontally reinforced areas of individual jet grouting piles are connected to form a wall panel. The foundation is connected below the vertical reinforced body, and the cushion layer is connected above it. The construction method of the structure includes the following steps: (1) Construction of diaphragm wall and vertical reinforcement around the foundation pit: level the site, surveyors lay out the axis position of the diaphragm wall according to the coordinates, construct the guide wall, then mix mud for mud wall protection, use grab bucket to form the diaphragm wall trench, use lock pipe to form a semi-concave tenon joint, treat the joint of the diaphragm wall section, and construct the vertical reinforcement. (2) Excavation of the foundation pit: After the diaphragm wall and the vertical reinforcement body have reached the required strength, the foundation pit will be excavated. During the excavation process, the foundation pit should be supported before excavation, the water should be dewatered before excavation, and the excavation should be carried out in layers, zones and symmetrically. (3) Lateral reinforcement of soil: After excavation to the foundation, the high-pressure jet grouting pile positions are marked on the foundation surface and the high-pressure jet grouting piles are constructed. After the construction of a single jet grouting pile lateral reinforcement area is completed, it is connected with other reinforcement areas to form a whole and form a wall panel. (4) Inspection: After the wall panel construction is completed, steel plates are driven into the joint to check whether the joint is in place. If it is not in place, jet grouting piles are carried out again at the joint as a reinforcement measure. (5) Subbase construction: After the wall panel construction is completed and passes inspection, the base subbase or bottom plate is constructed, and then the superstructure is constructed.

2. The structure for reinforcing ultra-large silt deep foundation pits with combined wall panels and composite foundations according to claim 1, characterized in that, The wall panel has one or two layers.

3. The structure for reinforcing ultra-large silt deep foundation pits with combined wall panels and composite foundations according to claim 1, characterized in that, The vertical reinforcement body is a vertically elongated reinforcement body that can form in the soil. The construction of the vertical reinforcement body includes treatment methods such as grouting reinforcement and compaction reinforcement of the foundation.

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