Foundation pit support structure of deep and thick soft soil rich in confined water

Abstract

The utility model relates to the technical field of foundation pit engineering construction and design, in particular to a foundation pit support structure of a deep and thick confined water-rich soft soil texture. The top of the underground diaphragm wall and the inner side of the underground diaphragm wall are connected with steel supports; the cement soil partition curtain is fixed on the periphery of the underground diaphragm wall; the cement soil partition curtain is vertically arranged in the lower-layer stable water-resisting layer by a certain depth L; the depth of the cement soil partition curtain is larger than that of the underground diaphragm wall. The enclosure structure of the cement soil partition curtain and the suspension type short enclosure wall is adopted, the bearing capacity of an enclosure retaining soil body is guaranteed, meanwhile, the water stopping capacity of the foundation pit is improved, the using amount of concrete and reinforcing steel bars of the reinforced concrete wall is effectively reduced, the engineering cost is reduced, and the cost is saved.

Description

Technical Field

[0001] This utility model relates to the field of foundation pit engineering construction and design technology, specifically to a foundation pit retaining structure in deep, confined water-rich soft soil geology. Background Technology

[0002] Existing foundation pit retaining structures often employ diaphragm walls that completely penetrate confined aquifers to reach the underlying aquitard. However, this method has drawbacks. The diaphragm walls are quite deep, with some projects reaching depths of 50-70 meters or even deeper. This results in excessive concrete and steel reinforcement usage, leading to high project costs. Furthermore, the deep trenches and long construction times make the walls highly susceptible to borehole collapse and shrinkage in soft soil, potentially causing ground subsidence. Uneven wall thickness, sand inclusions in the poured concrete, and faults also increase safety risks. Additionally, the steel reinforcement cages are often too tall and heavy, increasing the difficulty and risk of hoisting them.

[0003] Meanwhile, existing foundation pit retaining structures still employ a scheme of using bored piles + water-stop curtains to penetrate confined aquifers into the lower impermeable layer, which is limited to projects with relatively shallow foundation pit depths and shallow confined aquifers. Furthermore, current foundation pit water-stop curtains mostly use densely packed mixing piles outside the bored retaining piles or jet grouting piles between the bored piles. Both methods suffer from drawbacks such as poor verticality control and lower pile quality with increasing depth. Additionally, both mixing piles and jet grouting piles require mechanical drilling for each hole, resulting in low efficiency.

[0004] In summary, in foundation pit engineering in deep, confined aquifer soft soil geology, the issue of water permeability at the four walls and bottom of the foundation pit must be properly addressed. Existing retaining structures that form barriers by penetrating confined aquifer strata have limitations such as poor economic efficiency, construction difficulties, and difficulty in quality control when the confined aquifer strata are at considerable depths. Utility Model Content

[0005] To address the problems existing in the prior art, this utility model designs a foundation pit retaining structure for deep, water-rich, soft soil geology, which has advantages such as high economic efficiency, low construction difficulty, and controllable quality. The specific technical solution is as follows:

[0006] A foundation pit retaining structure for deep, confined, soft soil geology, comprising:

[0007] The foundation pit has a main structural base plate at its bottom, and a reinforced concrete frame structure is provided on the main structural base plate.

[0008] The diaphragm wall is fixed around the perimeter of the foundation pit, and the top and inner sides of the diaphragm wall are connected to steel or concrete supports.

[0009] A cement-soil partition curtain is vertically arranged and fixed at a depth L in a lower stable water-resisting layer outside the periphery of the underground continuous wall, and the depth of the cement-soil partition curtain is greater than the depth of the underground continuous wall.

[0010] Preferably, the vertical embedded depth Ld of the underground continuous wall is 0.8-2 times the depth H of the foundation pit.

[0011] Preferably, the depth L in the lower stable water-resisting layer is greater than or equal to 1 m.

[0012] Preferably, the thickness of the cement-soil partition curtain is 0.5-1.0 m.

[0013] Preferably, the cement-soil partition curtain is a mixture of cement slurry and / or water glass slurry and soil.

[0014] Preferably, the inside of the underground continuous wall is connected with the steel support or concrete support through a waist beam.

[0015] Preferably, the top of the underground continuous wall is provided with a corona beam connected with the steel support or concrete support.

[0016] Preferably, the underground continuous wall is an underground continuous pile wall.

[0017] Preferably, the distance between the underground continuous wall and the cement-soil partition curtain is 100-200 mm.

[0018] Compared with the prior art, the utility model has the beneficial effects that:

[0019] (1) The cement-soil partition curtain vertically penetrates the confined water stratum and enters the lower water-resisting layer, and can effectively form a partition curtain to hinder the water around the foundation pit from permeating to the four walls and the bottom of the foundation pit, especially in deep and thick soft soil stratum with confined water, has high applicability, and can effectively guarantee the safety of the foundation pit.

[0020] (2) The enclosure structure of the cement-soil partition curtain + suspended short enclosure wall (pile) has the semi-rigid partition curtain which is beneficial to improve the bearing capacity of the enclosure and retaining soil body, can effectively reduce the amount of concrete and steel bars of the reinforced concrete wall, and reduces the engineering cost and saves the cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] The utility model will be further explained in detail in combination with the drawings and specific embodiments.

[0022] Figure 1 is the plane schematic view of the foundation pit partition curtain + underground continuous wall enclosure structure of the utility model.

[0023] Figure 2It is a plane schematic view of the foundation pit partition curtain + bored pile enclosure structure of the utility model.

[0024] Figure 3 It is a section schematic view of the foundation pit enclosure structure of the utility model.

[0025] Figure 4 It is a trenching and grouting construction schematic view of the foundation pit partition curtain of the utility model.

[0026] Figure 5 It is a modification schematic view of the hydraulic trenching machine of the utility model.

[0027] In the drawing: 1, foundation pit; 2, main structure bottom plate; 3, reinforced concrete frame structure; 4, underground continuous wall; 5, steel support; 6, cement-soil partition curtain; 7, steel waist beam; 8, crown beam; S101, underground continuous wall trenching machine; 9, S102, trenching machine main machine; S103, trenching machine grab bucket; S104, grouting trolley; S105, grouting hose; S106, guide wall; S201, grouting steel guide pipe; S202, grouting nozzle. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0029] Referring to Figures 1 to 3 , 100-site surface soil; 200-weakly permeable layer clay; 300-soft soil layer silt or fine sand; 400-highly permeable layer sand layer; 500-permeable layer; 600-weakly permeable layer residual soil; 700-stable water-resisting layer, the embodiment 1 of the utility model is as follows:

[0030] A foundation pit enclosure structure of deep and thick soft soil with rich confined water, comprising:

[0031] The foundation pit 1 is provided with the main structure bottom plate 2 at the bottom, and the reinforced concrete frame structure 3 is arranged on the main structure bottom plate 2;

[0032] The underground continuous wall 4 fixed on the periphery of the foundation pit 1: the crown beam 8 is arranged at the top of the underground continuous wall 4, and the crown beam 8 is connected with the steel support 5; the steel support 5 is connected with the underground continuous wall 4 through the steel waist beam 7 at the inner side of the underground continuous wall 4; the vertical embedding depth Ld of the underground continuous wall 4 is 0.8 times to 2 times of the foundation pit depth H, and the vertical embedding depth Ld is determined by the foundation pit enclosure stability calculation, and it is not required to cross the specific soil layer below without double control requirement;

[0033] Cement-soil partition curtain 6 fixed on the periphery of underground continuous wall 4: Cement-soil partition curtain 6 is vertically arranged in a lower stable water-resisting layer at a depth L; depth L≥1m; thickness of cement-soil partition curtain 6 is 0.5-1.0m; cement-soil partition curtain 6 is a mixture of cement slurry and / or water glass slurry and soil; top elevation of curtain is not lower than site groundwater level, bottom elevation should enter stable water-resisting layer below confined water stratum; curtain can effectively form and resist the penetration of surrounding groundwater, silt and the like into the excavation range;

[0034] Depth of cement-soil partition curtain 6 is greater than depth of underground continuous wall 4; spacing between underground continuous wall 4 and cement-soil partition curtain 6 is 100-200mm.

[0035] Example 2

[0036] Reference Figure 2 Underground continuous wall 4 can also be underground continuous pile wall, steel support 5 can also be concrete support; steel waist beam 7 can also be concrete waist beam, which is the main retaining structure of pit wall soil.

[0037] Construction method:

[0038] Step 1: Perform relevant preparatory work before implementation, including three-way leveling, construction range positioning and marking, construction machinery assembly, construction material delivery and the like;

[0039] Step 2: Modify trenching machine, such as Figure 5 Install grouting steel guide pipe S201 in place, synchronously install grouting nozzle S202, bottom of which does not exceed the minimum opening range of grab bucket S103, connect and fasten grouting hose S105 with grouting steel guide pipe S201, and connect the other end with grouting trolley S104;

[0040] Step 3: Perform construction measurement, position control lines of cement-soil partition curtain 6, lay out guide wall excavation range, dig trench, excavate to guide wall bottom elevation, then perform guide wall reinforcement binding and erect guide wall wooden formwork, pour guide wall concrete, and use clay to layer-wise compact guide wall back; after guide wall concrete strength reaches 70% of design strength, remove guide wall wooden formwork, and finally backfill and compact clay;

[0041] Step 4: Modify trenching machine S101 in place, start trenching and soil excavation, initially inject prepared slurry with specific gravity of about 2.0, when trenching depth reaches 2m or below, start to synchronously supplement cement slurry or double-liquid slurry, until the trench section reaches design elevation.

[0042] Step 5, detect the mud specific gravity of the groove section, according to the situation, mix cement or clay particles with slurry, use the up and down agitation of the groove machine S101 to make the cement soil mixture uniform. After the completion of the first groove section, prepare the third groove section of the interval jump groove method, repeat the above steps;

[0043] Step 6, after the initial setting of the cement soil of the first and third groove sections, the second groove section between them can be constructed, the occlusion width between the groove sections is not less than 150mm. In this order, the whole of the partition curtain is completed.

[0044] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but rather can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered exemplary and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and all changes falling within the meaning and range of equivalence of the essential features of the claims are intended to be embraced therein. Any reference signs in the claims should not be considered as limiting the claims involved.

Claims

1. A deep and thick soft soil ground with confined water, which is a foundation pit retaining structure, characterized by, It comprises: a foundation pit (1) with a main structure bottom plate (2) at the bottom, and a reinforced concrete frame structure (3) arranged on the main structure bottom plate (2); an underground continuous wall (4) fixed at the periphery of the foundation pit (1), and a steel support (5) connected to the top and inner side of the underground continuous wall (4); a cement-soil partition curtain (6) vertically arranged and fixed at the periphery of the underground continuous wall (4) at a depth L in the lower stable water-resisting layer, and the depth of the cement-soil partition curtain (6) is greater than that of the underground continuous wall (4).

2. The deep thick soft soil ground with confined water of claim 1, wherein The vertical embedded depth Ld of the underground continuous wall (4) is 0.8-2 times the depth H of the foundation pit.

3. The deep thick soft soil ground with confined water of claim 1, wherein The depth L in the lower stable water-resisting layer is greater than or equal to 1 m.

4. The deep thick soft soil ground with confined water of claim 1, wherein The thickness of the cement-soil partition curtain (6) is 0.5-1.0 m.

5. The deep thick soft soil ground with confined water of claim 1, wherein The cement-soil partition curtain (6) is a mixture of cement slurry and / or water glass slurry and soil.

6. The deep thick soft soil ground with confined water of claim 1, wherein The inner side of the underground continuous wall (4) is connected to the steel support (5) through a waist beam (7).

7. The deep thick soft soil ground with confined water of claim 1, wherein The top of the underground continuous wall (4) is provided with a corbel (8) connected to the steel support (5).

8. The deep thick soft soil ground with confined water retaining structure of foundation pit according to claim 1, characterized in that, The underground continuous wall (4) is an underground continuous pile wall.

9. The deep thick soft soil ground with confined water retaining structure of foundation pit according to claim 1, characterized in that, The distance between the underground continuous wall (4) and the cement-soil partition curtain (6) is 100-200 mm.

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