Sectional arc-shaped underground diaphragm wall supporting system

Abstract

The utility model provides a segmented arc-shaped underground diaphragm wall supporting system, and relates to the technical field of foundation pit supporting, the segmented arc-shaped underground diaphragm wall supporting system comprises arc-shaped sections, the arc-shaped sections are formed by concrete pouring and symmetrically arranged on two side walls of a foundation pit respectively, and the outer arc surfaces of the arc-shaped sections are tightly attached to the side walls of the foundation pit and used for bearing water and soil pressure of the side walls of the foundation pit; and the inner support is formed by pouring concrete, and the two ends of the inner support are fixedly connected with the arc-shaped sections arranged on the two side walls of the foundation pit correspondingly. According to the arc-shaped underground diaphragm wall, the axial inertia moment is increased through the arc-shaped section, and the arc-shaped structure is beneficial to bending resistance, so that compared with a rectangular underground diaphragm wall with the same thickness, the arc-shaped underground diaphragm wall can effectively improve the vertical and horizontal bearing capacity. And the arc-shaped underground diaphragm wall can increase the supporting distance under the condition that the thickness of the wall body is kept unchanged, and the construction operation space in the foundation pit is optimized.

Description

Technical Field

[0001] This invention relates to the field of foundation pit support technology, and more specifically, to a segmented arc-shaped underground continuous wall support system. Background Technology

[0002] With the large-scale construction of railways, urban rail transit, municipal utility tunnels and other projects in my country, the open-cut method is often used for the construction of railways, subway stations, open-cut sections and municipal utility tunnels in cities. In order to reduce the excavation range of the open-cut foundation pit and reduce the impact on the surrounding environment, foundation pit support structures are required during foundation pit excavation to ensure the stability of the foundation pit.

[0003] However, foundation pit support structures are often used as temporary structures. When calculating the main underground structure, the beneficial effects of temporary support structures are often not considered. Therefore, it can be assumed that the foundation pit support structure is ineffective under permanent service conditions, and thus, the lower the engineering investment, the better the project's economic efficiency. This necessitates adopting support types that can provide temporary support while effectively reducing engineering investment. Currently, conventional underground station and utility tunnel foundation pits are mostly rectangular, limiting the space for structural optimization. New foundation pit support structures need to be developed to achieve the optimal technical and economic efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a segmented arc-shaped underground continuous wall support system to improve the aforementioned problems. To achieve this purpose, the technical solution adopted by this invention is as follows:

[0005] In a first aspect, this application provides a segmented arc-shaped diaphragm wall support system, comprising:

[0006] The arc-shaped segments, formed by concrete casting, are symmetrically arranged on both sides of the foundation pit, with their outer arc surfaces closely attached to the side walls of the foundation pit to bear the water and soil pressure of the side walls of the foundation pit.

[0007] The internal support is formed by concrete pouring, and its two ends are fixedly connected to the arc-shaped sections set on the two side walls of the foundation pit.

[0008] Furthermore, straight joints are provided at both ends of the arc-shaped segment, and the inner support is fixedly connected to the arc-shaped segment through the straight joints.

[0009] Furthermore, an I-beam joint is pre-embedded at the end of the straight joint, and adjacent diaphragm walls are spliced ​​and fixed through the I-beam joint.

[0010] Furthermore, adjacent diaphragm walls can share the same internal support.

[0011] Furthermore, the length of the straight joint is related to the number of internal supports between adjacent diaphragm walls.

[0012] Furthermore, seepage-proof and water-blocking structures are provided at the joints between adjacent diaphragm walls.

[0013] Furthermore, a concrete capping beam is poured on top of the adjacent underground continuous wall.

[0014] Furthermore, the arc-shaped segment of the diaphragm wall is either a circular arc or a parabola.

[0015] Furthermore, the internal bracing and reinforcement of the curved section of the diaphragm wall are different.

[0016] Furthermore, a support structure is provided on the top of the concrete cap beam.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention employs an arc-shaped diaphragm wall. By increasing the axial moment of inertia through the arc-shaped cross-section and leveraging the bending resistance advantage of the arched structure, the arc-shaped diaphragm wall effectively enhances both vertical and horizontal load-bearing capacity compared to a rectangular diaphragm wall of the same thickness. Furthermore, the arc-shaped diaphragm wall allows for increased support spacing while maintaining a constant wall thickness, optimizing the construction workspace within the foundation pit.

[0019] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing embodiments of the invention. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the segmented arc-shaped underground continuous wall support structure described in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the I-beam joint structure described in an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of another segmented arc-shaped underground continuous wall support structure described in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram illustrating the vertical bearing capacity calculation angle as described in an embodiment of the present invention;

[0025] Figure 5This is a schematic diagram illustrating the calculation angle of the lateral bearing capacity in an embodiment of the present invention.

[0026] Marked in the diagram: 1. Arc segment; 2. Internal support; 3. Straight joint; 4. Waterproofing and leak-proofing structure. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0029] Example 1:

[0030] See Figure 1 This embodiment provides a segmented arc-shaped underground continuous wall support system.

[0031] Arc-shaped segment 1, formed by concrete pouring, is symmetrically set on both sides of the foundation pit. Its outer arc surface is in close contact with the side wall of the foundation pit to bear the water and soil pressure of the side wall of the foundation pit.

[0032] The inner support 2 is formed by concrete pouring, and its two ends are fixedly connected to the arc-shaped segments 1 set on both sides of the foundation pit.

[0033] Specifically, for long, narrow foundation pits, a segmented approach is adopted. Each segment is supported by a diaphragm wall consisting of an arc-shaped section 1 and internal supports 2, with internal supports between adjacent diaphragm walls. Each diaphragm wall is a three-section structure, such as... Figure 1 As shown, the left and right ends are internal supports 2, and the middle section is an arc-shaped section 1, which is mainly used to bear the water and soil pressure on the side wall of the foundation pit. The arc section 1 can be in the form of a circular arc or a parabola, and the sag-to-span ratio of the arc section can be determined by calculation.

[0034] The curved segment 1 has straight joints 3 at both ends, and the inner support 2 is fixedly connected to the curved segment 1 through the straight joints 3. The end of the curved segment 1 is designed as a straight line to be fixedly connected to both ends of the inner support 2, ensuring a smooth transition of the connection, so that the curved segment 1 and the inner support 2 can be reliably connected to form a complete underground continuous wall structure.

[0035] I-beam joints are pre-embedded at three ends of the straight joint, and adjacent diaphragm walls are spliced ​​and fixed using these I-beam joints. For example... Figure 2 The diagram shows a pre-embedded I-beam joint. This pre-embedded joint effectively prevents misalignment of adjacent diaphragm wall joints and improves overall rigidity. The I-beam joint is typically perpendicular to the wall. During wall construction, the newly poured diaphragm wall encloses the I-beams of the original diaphragm wall, achieving the splicing.

[0036] Adjacent diaphragm walls can share the same internal support 2; the length of the straight joint 3 is related to the number of internal supports 2 between adjacent diaphragm walls. The supports for adjacent diaphragm walls are set at the joints of the two wall sections. Depending on the load-bearing requirements, one support can be set on each floor, or two supports can be set on each floor, i.e., whether adjacent diaphragm walls share the same internal support. When one support is set, i.e., as shown... Figure 1 As shown, adjacent diaphragm walls use the same internal support 2. The length of the internal support at the straight joint 2 at both ends of the arc segment 1 can be set shorter, that is, the sum of the internal supports at the straight joint 2 at the splicing of adjacent diaphragm walls should be greater than the support width; when two supports are set, as shown... Figure 3 As shown, when adjacent diaphragm walls use their respective internal supports 2, the straight lines at the straight joints 2 at both ends of the corresponding arc segment 1 need to be longer, and the splicing joints of two adjacent diaphragm walls are located between the two internal supports 2.

[0037] A seepage-proof and water-blocking structure 4 is provided at the joint of adjacent diaphragm walls. When there is abundant groundwater in the foundation pit, a seepage-proof and water-blocking structure 4 is added to the outside of the joint of adjacent diaphragm walls. This can be achieved by using jet grouting piles or other methods to reinforce the joint, improve the waterproofing and reinforcement performance of the diaphragm wall joint, and ensure the stability and durability of the entire structure in long-term use.

[0038] A concrete capping beam is poured on top of the adjacent diaphragm wall. After the diaphragm wall is poured, pouring a concrete capping beam on top of the wall can improve the integrity of the diaphragm wall and provide the first layer of concrete support.

[0039] The curved segment 1 of the diaphragm wall can be either circular or parabolic. In practical foundation pit applications, these two shapes can be chosen to optimize the load-bearing capacity of the diaphragm wall on the sidewalls. A circular arc generally has better uniform stress distribution, suitable for evenly distributing lateral pressure over a large area. A parabolic shape can better adapt to changes in lateral earth pressure at different heights, making it suitable for deep foundation pits or situations with significant stress variations.

[0040] The reinforcement of the internal support 2 and the curved segment 1 of the diaphragm wall differs. Because the stress characteristics of the curved segment 1 differ from the specific function of the internal support 2, different reinforcement ratios are required. The curved segment 1 typically experiences greater bending and shear forces, thus requiring more reinforcement to provide bending and shear strength. The internal support 2, due to its more uniform stress distribution, requires less reinforcement, but still needs to ensure strength and stability.

[0041] A supporting structure is installed at the top of the concrete capping beam. This supporting system, installed on top of the concrete capping beam, is typically used to enhance structural stability, especially during foundation pit excavation. Internal bracing effectively prevents the walls from deforming or tilting due to earth pressure or other factors. The supporting structure maintains the overall stability of the structure by sharing some of the lateral earth pressure and reducing deformation and displacement of the foundation pit sidewalls.

[0042] The construction of an arc-shaped diaphragm wall can be carried out according to the following steps:

[0043] The first step is the construction of the guide wall: an arc-shaped guide wall is built on the ground to guide the trenching construction and prevent collapse. Once the concrete of the guide wall reaches the required strength, the next step of construction can proceed.

[0044] The second step is trench excavation: An arc-shaped diaphragm wall trenching machine is used to excavate the underground trench walls along the arc-shaped guide wall path, controlling the trench depth and width to ensure the accuracy of the arc section and the continuity of the wall. Mud slurry wall protection technology is used to prevent collapse.

[0045] The third step is the installation of the reinforcing cage: make an arc-shaped reinforcing cage to ensure that it conforms to the design curvature, hoist the reinforcing cage into the trench, adjust its position, and fix it in place.

[0046] Step 4: Concrete pouring: Concrete is poured using the tremie pipe method to ensure the wall is dense and uniform. Reinforcing bars for the capping beam joint are pre-installed at the top of the wall for subsequent capping beam construction.

[0047] The fifth step is the construction of the capping beam: a concrete capping beam is poured on top of the wall to connect the various sections of the underground continuous wall and improve the overall stability.

[0048] Step 6: Excavation and Support Construction of the Foundation Pit: Excavate the foundation pit to 50cm below the bottom of the first support layer and construct the first support layer. Continue excavating downwards, constructing the corresponding support layer after each excavation to ensure the safety of the foundation pit.

[0049] Example 2:

[0050] This embodiment provides a calculation method for improving the vertical bearing capacity performance of a continuous wall under an arc shape:

[0051] like Figure 4 As shown, the formula for calculating the axial moment of inertia of an arc-shaped cross-section is:

[0052]

[0053] Among them, I 弧 R is the axial moment of inertia of the arc-shaped section; R is the radius of the arc-shaped diaphragm wall; α is the starting angle of the arc-shaped diaphragm wall; h1 is the thickness of the arc-shaped diaphragm wall.

[0054] The formula for calculating the axial moment of inertia of a rectangular cross-section is:

[0055]

[0056] Among them, I 矩 λ is the axial moment of inertia of the rectangular cross section; b is the width of the rectangular diaphragm wall; and h2 is the thickness of the rectangular diaphragm wall.

[0057] The formula for calculating bending stress is:

[0058]

[0059] Where σ is the bending stress; M is the bending moment; y is the calculated height of the section; and I is the axial moment of inertia of the section.

[0060] From the formula for calculating bending stress, the formula for increasing the bearing capacity when the calculated cross-sectional height is equal is:

[0061]

[0062] Among them, I 弧 R is the axial moment of inertia of the curved section; R is the radius of the curved diaphragm wall; α is the starting angle of the curved diaphragm wall; h1 is the thickness of the curved diaphragm wall; I 矩 denoted as axial moment of inertia of the rectangular cross-section; b is the width of the rectangular diaphragm wall; h2 is the thickness of the rectangular diaphragm wall; k1 is the bearing capacity enhancement factor of the curved diaphragm wall in the vertical direction.

[0063] Considering that the calculated cross-sectional height of an arc-shaped diaphragm wall is generally greater than that of a rectangular diaphragm wall, the actual load-bearing capacity of an arc-shaped diaphragm wall will be greater than the result calculated by the above formula.

[0064] Example 3:

[0065] This embodiment provides a calculation method for improving the lateral bearing capacity performance of a continuous wall under an arc shape:

[0066] like Figure 5 As shown, the transverse bending moment of the curved section:

[0067]

[0068] Among them, M K The transverse bending moment of the curved section; F represents the bending moment at the same cross-section of a regular straight beam with the same span, and y represents the arc height at the calculated cross-section of the curved diaphragm wall; H This refers to the horizontal thrust at the end of the curved diaphragm wall.

[0069] Compared to ordinary straight beams, curved diaphragm walls generate an additional horizontal thrust at their ends due to their curvature. This thrust induces additional internal forces within the curved structure, reducing the bending moment of the curved wall under stress and thus improving its load-bearing capacity.

[0070] The formula for calculating the horizontal thrust at the end is as follows:

[0071]

[0072] Among them, F H This refers to the horizontal thrust at the end of the arc-shaped diaphragm wall; f is the mid-span bending moment of a regular straight beam with the same span; f is the sag of the curved diaphragm wall.

[0073] The formula for increasing the lateral bearing capacity of the cross-section after adopting an arc-shaped diaphragm wall is:

[0074]

[0075] Among them, M K The transverse bending moment of the curved section; F represents the bending moment at the same cross-section of a regular straight beam with the same span, and y represents the arc height at the calculated cross-section of the curved diaphragm wall; H k1 represents the horizontal thrust at the end of the curved diaphragm wall; k2 represents the bearing capacity enhancement coefficient of the curved diaphragm wall in the transverse direction.

[0076] Due to the structural characteristics of the curved diaphragm wall, the horizontal thrust F generated at the end... H It can share part of the bending moment, thus reducing the actual bending moment.

[0077] When M K When the diameter decreases, it means that the bending resistance of the underground continuous wall increases, so the bearing capacity coefficient k2>1, that is, the bearing capacity of the curved wall is higher than that of the ordinary straight beam.

[0078] The greater the sag f of the curved diaphragm wall, the greater F HThe larger M is K The greater the descent, the larger k2 becomes, and the stronger the bearing capacity of the curved diaphragm wall.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0080] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A segmented arc diaphragm wall support system, characterized in that, The utility model relates to a kind of underground continuous wall, including: Arc segment (1), the arc segment (1) is formed by concrete pouring, respectively symmetrically arranged in the two side walls of foundation pit, its outer arc surface is close to the side wall of foundation pit, for bearing the water and soil pressure of side wall of foundation pit; Inner support (2), the inner support (2) is formed by concrete pouring, its two ends are fixedly connected with the arc segment (1) arranged in the two side walls of foundation pit.

2. The segmented arc diaphragm wall support system of claim 1, wherein ,The arc segment (1) two ends are provided with linear joint (3), and the inner support (2) is fixedly connected with the arc segment (1) by the linear joint (3).

3. The segmented arc-shaped diaphragm wall support system of claim 2, wherein ,The linear joint (3) end is embedded with I-steel joint, and adjacent underground continuous wall is spliced and fixed by the I-steel joint.

4. The segmented arc underground diaphragm wall support system of claim 3, wherein ,Adjacent underground continuous wall can share the same inner support (2).

5. The segmented arc-shaped diaphragm wall support system of claim 3, wherein ,The length of the linear joint (3) is related to the number of inner support (2) between adjacent underground continuous wall.

6. The segmented arc-shaped diaphragm wall support system of claim 3, wherein ,The splicing position of adjacent underground continuous wall is provided with anti-seepage water plugging structure (4).

7. The segmented arc-shaped diaphragm wall support system of claim 3, wherein ,The top of the adjacent underground continuous wall is poured with concrete crown beam.

8. The segmented arc underground diaphragm wall support system of claim 1, wherein ,The arc segment (1) of the underground continuous wall is circular arc or parabolic.

9. The segmented arc diaphragm wall support system of claim 1, wherein ,The inner support (2) and arc segment (1) of the underground continuous wall are different in reinforcement.

10. The segmented arc underground diaphragm wall support system of claim 7, wherein ,The top of the concrete crown beam is provided with support structure.

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