Foundation pit supporting structure

Abstract

The invention relates to the field of constructional engineering, and discloses a foundation pit supporting structure which comprises a foundation trench, steel sheet piles are installed on the periphery of the inner wall of the foundation trench, one end of each steel sheet pile penetrates into the foundation trench, a waist beam is installed on one side of the inner wall of each steel sheet pile, a steel pipe is installed in each waist beam, and the foundation trench is filled with a supporting layer. The steel pipe is used for foundation supporting of a foundation pit, and an extending mechanism is installed in the steel pipe and used for increasing the supporting area of the steel pipe. The overall stability is effectively enhanced through the synergistic effect of multiple components, the steel sheet piles are driven into the ground along the inner wall of the foundation trench, soil collapse is preliminarily resisted by means of bending resistance and shear resistance of the steel sheet piles, the steel sheet piles are connected into a whole through the waist beams, uniform transmission and distribution of force are achieved, and the supporting structure can jointly resist lateral pressure; the whole structure is compact and stable, the complex soil body pressure condition can be better dealt with, the foundation pit collapse risk is reduced, and it is guaranteed that foundation pit construction is conducted safely and orderly.

Description

Technical Field

[0001] The invention relates to the technical field of construction engineering, in particular to a foundation pit supporting structure. Background Art

[0002] In the foundation construction of various construction projects, foundation pit support is a crucial link, which is directly related to the safety, stability and protection of the surrounding environment of the project. With the rapid development of urban construction, the scale and complexity of construction projects are constantly increasing, and the requirements for foundation pit support structures are becoming increasingly stringent.

[0003] Traditional foundation pit support methods, such as simple soil nail wall support, often expose many limitations when facing deeper foundation pits or poor soil conditions. Soil nail walls mainly rely on the friction and adhesion between soil nails and soil to maintain soil stability. However, in soft soil, the bearing capacity of the soil is low, and soil nails are difficult to provide sufficient anchoring force, which can easily lead to excessive deformation of the soil or even collapse. In sandy soil, due to the weak adhesion between sand particles, the integrity and stability of the soil nail wall are also difficult to ensure, and it cannot effectively resist the fluidity and lateral pressure of the sand.

[0004] Another example is some simple steel sheet pile supports. Although steel sheet piles have certain bending and shear resistance, their single structural form is difficult to meet the complex force requirements for large foundation pits or long construction periods. As the depth of the foundation pit increases, the lateral pressure on the steel sheet piles increases sharply, and deformation and displacement problems are prone to occur, which in turn affects the safety of the foundation pit. Moreover, traditional steel sheet pile supports often have shortcomings in water stopping. Groundwater can easily penetrate into the foundation pit through the gaps between the steel sheet piles, causing water accumulation in the foundation pit, increasing the difficulty of construction, and even deteriorating the mechanical properties of the soil due to the water pressure, further endangering the stability of the support structure. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a foundation pit support structure, which solves the problem that steel sheet piles are prone to deformation and displacement, thereby affecting the safety of the foundation pit.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: a foundation pit support structure, including a foundation trench, wherein steel sheet piles are installed around the inner wall of the foundation trench, one end of the steel sheet piles extends into the interior of the foundation trench, a waist beam is installed on one side of the inner wall of the steel sheet pile, a steel pipe is installed inside the waist beam, the interior of the foundation trench is filled with a supporting layer, which is used to support the foundation pit, and an extension mechanism is installed inside the steel pipe, which is used to increase the supporting area of ​​the steel pipe.

[0007] Preferably, the supporting layer includes a backfill layer, which is filled on the inner bottom wall of the foundation trench, a concrete layer is arranged on the top of the backfill layer, the concrete layer is wrapped on the outer wall of the steel pipe, the outside of the concrete layer is filled with a dense layer, and the top of the dense layer is filled with a stone chip layer.

[0008] Preferably, the extension mechanism includes an internal frame, which are respectively installed at the two ends of the interior of the steel pipe, and a driven bevel gear is rotatably connected to one side of the outer wall of the internal frame on one side, and one end of a threaded rod is installed on the outer wall of the driven bevel gear, and the other end of the threaded rod passes through the internal frame, and a nut is threadedly connected to the outer wall of the threaded rod, and a retraction rod is installed inside the nut and the internal frame, one end of an extension rod is installed on one side of the outer wall of the nut, and a top cone is installed on the other end of the extension rod, a slide is provided on one side of the outer wall of the steel pipe, and a slide groove is provided on the outer wall of the internal frame on the other side, and an extension plate is slidably connected to the inside of the slide groove, and one end of the top cone passes through the internal frame on one side.

[0009] Preferably, a positioning block is installed on one side of the outer wall of the extension plate, one end of a tension spring is installed on one side of the outer wall of the positioning block, and the other end of the tension spring is installed on the inner wall of the steel pipe.

[0010] Preferably, a driving bevel gear is rotatably connected to one side of the outer wall of the steel pipe, and the driving bevel gear is meshingly connected to the driven bevel gear.

[0011] Preferably, a handle is installed on one side of the outer wall of the active bevel gear.

[0012] Preferably, one end of the extension plate is fan-shaped.

[0013] Preferably, one side of the inner wall of the steel sheet pile is installed with one side of the outer wall of the support frame, and the other side of the outer wall of the support frame is fixedly connected to the bottom of the waist beam.

[0014] Preferably, the dense layer is filled to the horizontal top of the steel pipe, and the stone chip layer is filled to the horizontal bottom of the waist beam.

[0015] Preferably, the backfill layer material is thick medium-coarse sand, and the filling material of the dense layer is medium-coarse sand.

[0016] The present invention provides a foundation pit support structure having the following beneficial effects: 1. The present invention effectively enhances the overall stability through the synergistic effect of multiple components. The steel sheet piles are driven into the ground along the inner wall of the foundation trench, relying on their own bending and shearing resistance to initially resist soil collapse. The waist beam connects the steel sheet piles into a whole, realizing uniform transmission and distribution of force, so that the support structure can jointly resist lateral pressure. The steel pipe, as the main supporting component, bears the pressure of the upper soil, and cooperates with the dispersed buffering, gap filling and drainage functions of each layer in the support layer, so that the whole structure is tight and stable, which can better cope with complex soil pressure conditions, reduce the risk of foundation pit collapse, and ensure the safe and orderly construction of the foundation pit.

[0017] 2. The setting of the extension mechanism of the present invention gives the support structure the advantage of adjustable support area. When faced with different soil pressure conditions or different requirements for support strength during the construction stage, the extension plate is expanded outward through transmission to increase the support area of ​​the steel pipe, thereby improving the resistance of the entire structure to the soil pressure above. In addition, when renovation is required, the tension spring can drive the extension plate to automatically retract, which is convenient to operate and saves manpower. It can more flexibly adapt to various working conditions, optimize the support effect, and extend the applicability period of the support structure.

[0018] 3. In the present invention, the backfill layer in the support layer adopts thick medium-coarse sand and the dense layer adopts medium-coarse sand, both of which have good water permeability, which can prevent groundwater from accumulating at the bottom of the foundation pit and avoid damage to the support structure due to excessive water pressure. The density of the thick medium-coarse sand can also buffer the pressure from above, and the dense layer can fill the gap between the concrete layer and the surrounding soil, maintain the stability of the soil around the support structure, reduce the adverse effects of groundwater on the foundation pit support, and ensure the stability of the support structure under complex groundwater level conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a three-dimensional diagram of the support structure of the present invention; Figure 2 is a schematic diagram of the support structure in the present invention; Figure 3 It is a display diagram of the support structure in the present invention; Figure 4 is a cross-sectional view of the extension mechanism of the present invention; Figure 5 is a schematic diagram of the extension mechanism of the present invention; Figure 6 for Figure 5 A in the enlarged view; Figure 7 is a schematic diagram of the supporting layer in the present invention; Figure 8 It is a schematic diagram of the support frame in the present invention.

[0020] Among them, 1. foundation trench; 2. steel sheet piles; 3. waist beam; 4. steel pipe; 5. support layer; 501. backfill layer; 502. concrete layer; 503. dense layer; 504. stone chip layer; 6. extension mechanism; 601. built-in frame; 602. driven bevel gear; 603. threaded rod; 604. nut; 605. retractable rod; 606. extension rod; 607. top cone; 608. slide; 609. extension plate; 610. positioning block; 611. tension spring; 612. active bevel gear; 613. handle; 7. slide; 8. support frame. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please see attached Figure 1-8 The embodiment of the present invention provides a foundation pit support structure, including a foundation trench 1, a steel sheet pile 2 is installed around the inner wall of the foundation trench 1, one end of the steel sheet pile 2 penetrates into the foundation trench 1, a waist beam 3 is installed on one side of the inner wall of the steel sheet pile 2, a steel pipe 4 is installed inside the waist beam 3, the inside of the foundation trench 1 is filled with a support layer 5, which is used to support the foundation pit, and an extension mechanism 6 is installed inside the steel pipe 4, which is used to increase the support area of ​​the steel pipe 4; The supporting layer 5 includes a backfill layer 501, which is filled on the inner bottom wall of the foundation trench 1, a concrete layer 502 is arranged on the top of the backfill layer 501, the concrete layer 502 is wrapped on the outer wall of the steel pipe 4, a dense layer 503 is filled outside the concrete layer 502, and a stone chip layer 504 is filled on the top of the dense layer 503; The dense layer 503 is filled to the horizontal top of the steel pipe 4, and the stone chip layer 504 is filled to the horizontal bottom of the waist beam 3; The backfill layer 501 is made of thick medium-coarse sand, and the filling material of the compact layer 503 is made of medium-coarse sand; Specifically, when it is necessary to support the foundation pit, the steel sheet piles 2 are first driven into the ground along the inner wall of the foundation trench 1 so that one end thereof penetrates a certain depth into the foundation trench 1. The steel sheet piles 2 rely on their own bending and shearing resistance to initially prevent the collapse of the soil on the side wall of the foundation trench 1. After the steel sheet piles 2 are installed, the waist beam 3 is installed on one side of the inner wall of the steel sheet piles 2. The waist beam 3 plays a role of connection and support, connecting each steel sheet pile 2 into a whole, and enhancing the stability of the entire support structure. At the same time, the steel pipe 4 is installed inside the waist beam 3. The steel pipe 4 serves as the main supporting component and bears the pressure from the soil above. At this time, the supporting layer 5 in the foundation trench 1 begins to play a role. The backfill layer 501 is filled with thick medium-coarse sand on the inner bottom wall of the foundation trench 1. The thick medium-coarse sand has good water permeability and density, which can disperse and buffer the pressure from above to a certain extent and prevent groundwater from accumulating at the bottom. A concrete layer 502 is set on the top of the backfill layer 501. The concrete layer 502 is wrapped around the outer wall of the steel pipe 4. After the concrete solidifies, it forms a solid support body, which works together with the steel pipe 4 to further enhance the support capacity of the soil. The outside of the concrete layer 502 is filled with a dense layer 503. The dense layer 503 is filled with medium-coarse sand to the horizontal top of the steel pipe 4. The dense layer 503 of medium-coarse sand can fill the gap between the concrete layer 502 and the surrounding soil, making the entire support structure more compact and stable, and also play a certain drainage role. Finally, the stone chip layer 504 is filled on the top of the dense layer 503 to the horizontal bottom of the waist beam 3. The stone chip layer 504 can play a certain filtering and buffering role on the soil above, preventing fine particles from entering the support structure and affecting its performance. In addition, the stone chip layer 504 can also beautify the surrounding environment of the foundation pit to a certain extent.

[0023] The extension mechanism 6 includes an internal frame 601, which is respectively installed at the two ends inside the steel pipe 4, and a driven bevel gear 602 is rotatably connected to one side of the outer wall of the internal frame 601 on one side, and one end of a threaded rod 603 is installed on the outer wall of the driven bevel gear 602, and the other end of the threaded rod 603 passes through the internal frame 601, and a nut 604 is threadedly connected to the outer wall of the threaded rod 603, and a contraction rod 605 is installed inside the nut 604 and the internal frame 601, and one end of an extension rod 606 is installed on one side of the outer wall of the nut 604, and a top cone 607 is installed on the other end of the extension rod 606, a slideway 7 is provided on one side of the outer wall of the steel pipe 4, and a slide groove 608 is provided on the outer wall of the internal frame 601 on the other side, and an extension plate 609 is slidably connected inside the slide groove 608, and one end of the top cone 607 passes through the internal frame 601 on one side; A positioning block 610 is installed on one side of the outer wall of the extension plate 609, one end of a tension spring 611 is installed on one side of the outer wall of the positioning block 610, and the other end of the tension spring 611 is installed on the inner wall of the steel pipe 4; A driving bevel gear 612 is rotatably connected to one side of the outer wall of the steel pipe 4, and the driving bevel gear 612 is meshedly connected with the driven bevel gear 602; A handle 613 is installed on one side of the outer wall of the active bevel gear 612; One end of the extension plate 609 is fan-shaped; Specifically, when the supporting area of ​​the two ends of the steel pipe 4 on the steel sheet pile 2 needs to be increased, the operator needs to turn the handle 613 to drive the active bevel gear 612 to rotate, and the active bevel gear 612 is meshed with the driven bevel gear 602, and the driven bevel gear 602 rotates accordingly, thereby driving the threaded rod 603 to rotate. Because the threaded rod 603 is threadedly connected to the nut 604, and the retractable rod 605 provides a limiting effect on the nut 604, the nut 604 starts to move on the threaded rod 603. When the nut 604 moves, the extension rod 606 installed on one side of the outer wall of the nut 604 also moves accordingly, and the extension rod 606 pushes the top cone 607 to move outward. The top cone 607 passes through the built-in frame 601 on one side and presses the outer wall of the extension plate 609. As the top cone 607 continues to press, the extension plate 609 is subjected to an outward expansion force and begins to gradually expand outward, thereby increasing the support area of ​​the steel pipe 4. While the top cone 607 squeezes the extension plate 609, the tension spring 611 is stretched synchronously by force, and has a tendency to restore the original state. This tendency force automatically drives the extension plate 609 to retract when the nut 604 moves in the opposite direction. When the supporting structure of the foundation pit needs to be renovated, the tension spring 611 drives the extension plate 609 to automatically retract, thereby reducing the manpower consumption required for adjustment. In addition, since one end of the extension plate 609 is fan-shaped, the supporting area of ​​the steel pipe 4 is further increased, so that the steel pipe 4 can better resist the pressure from the upper soil, thereby improving the stability and bearing capacity of the entire foundation pit support structure.

[0024] One side of the inner wall of the steel sheet pile 2 is installed with one side of the outer wall of the support frame 8, and the other side of the outer wall of the support frame 8 is fixedly connected to the bottom of the waist beam 3; Specifically, the provision of the support frame 8 further enhances the connection stability between the steel sheet piles 2 and the waist beam 3. During the foundation pit support process, the steel sheet piles 2 bear the lateral pressure of the soil, and these pressures are transmitted to the waist beam 3 through the steel sheet piles 2. The support frame 8, as a supporting component, effectively shares the pressure transmitted to the waist beam 3 by the steel sheet piles 2, and prevents the waist beam 3 from being deformed or damaged due to uneven force. At the same time, the support frame 8 can also adjust the relative position between the steel sheet piles 2 and the waist beam 3 to ensure that the two always maintain a correct connection relationship during installation and use, thereby ensuring the integrity and stability of the entire foundation pit support structure, so that the support structure can better play its supporting role on the foundation pit and ensure the safety and smooth progress of the foundation pit construction.

[0025] Working principle: When it is necessary to support the foundation pit, the steel sheet pile 2 is first constructed. The steel sheet pile 2 is driven into the ground along the inner wall of the foundation trench 1 so that one end thereof penetrates a certain depth into the foundation trench 1. The steel sheet pile 2, with its own bending and shearing resistance, initially blocks the collapse of the soil on the side wall of the foundation trench 1, and provides a relatively stable working environment for subsequent construction. After the steel sheet pile 2 is installed, the waist beam 3 is installed on one side of the inner wall of the steel sheet pile 2. The waist beam 3 connects each independent steel sheet pile 2 into a whole, so that the stability of the entire support structure is enhanced. At this time, each steel sheet pile 2 realizes force transmission and The steel pipe 4 is used as the main supporting component to bear the pressure from the upper soil. The steel pipe 4 effectively transfers the vertical pressure of the upper soil to the supporting layer 5 and the foundation below to prevent excessive subsidence and collapse of the soil. At the same time, the supporting layer 5 in the foundation trench 1 begins to play a role. The backfill layer 501 is filled with thick and medium coarse sand on the inner bottom wall of the foundation trench 1. The thick and medium coarse sand has good permeability and density. Its permeability can prevent groundwater from accumulating at the bottom and avoid damage to the supporting structure due to excessive water pressure; the density can disperse and buffer the pressure from above to a certain extent, reducing the soil. In order to concentrate the force on the steel pipe 4 and other supporting components, a concrete layer 502 is set on the top of the backfill layer 501. The concrete layer 502 is wrapped around the outer wall of the steel pipe 4. After the concrete solidifies, it forms a solid support body, which is closely combined with the steel pipe 4 and works together. The concrete layer 502 can not only enhance the lateral constraint on the steel pipe 4 and improve its bearing capacity, but also further evenly distribute the pressure of the upper soil to the backfill layer 501 below and the surrounding soil. The outside of the concrete layer 502 is filled with a dense layer 503. The dense layer 503 is filled with medium-coarse sand to the horizontal top of the steel pipe 4. The dense filling of the medium-coarse sand can have The gap between the concrete layer 502 and the surrounding soil can be effectively filled, making the entire support structure more compact and stable. At the same time, the drainage performance of the medium-coarse sand also helps to maintain the stability of the soil around the support structure, preventing the softening of the soil and the instability of the support structure due to water accumulation. Finally, the stone chip layer 504 is filled on the top of the dense layer 503 to the horizontal bottom of the waist beam 3. The stone chip layer 504 can play a certain filtering and buffering role on the soil above, preventing fine particles from entering the support structure and affecting its performance. In addition, the stone chip layer 504 can also beautify the surrounding environment of the foundation pit to a certain extent, reducing the visual impact of the construction on the surrounding environment; When it is necessary to increase the supporting area of ​​the steel sheet pile 2 at both ends of the steel pipe 4, the operator rotates the handle 613. The rotation of the handle 613 drives the active bevel gear 612 to rotate. Since the active bevel gear 612 is meshed and connected with the driven bevel gear 602, the driven bevel gear 602 rotates accordingly, and then drives the threaded rod 603 to rotate. Because the threaded rod 603 is threadedly connected with the nut 604, and the contraction rod 605 gives the nut 604 a limiting effect, the rotational freedom of the nut 604 is limited, so that it can only move along the axis direction of the threaded rod 603. Therefore, the nut 604 begins to move on the threaded rod 603. When the nut 604 moves, the extension rod 606 installed on one side of the outer wall of the nut 604 also moves accordingly. The extension rod 606 pushes the top cone 607 to move outward. The top cone 607 passes through the built-in frame 601 on one side and presses the outer wall side of the extension plate 609. As the top cone 607 continues to press, the extension plate 609 is subjected to an outward expansion force and begins to gradually expand outward. Since one end of the extension plate 609 is fan-shaped, the support area of ​​the steel pipe 4 is further increased during the expansion process, so that the steel pipe 4 can better resist the pressure from the soil above, and improve the stability and bearing capacity of the entire foundation pit support structure. When the top cone 607 squeezes the extension plate 609, the tension spring 611 is stretched synchronously under force. The tension spring 611 has elastic potential energy to restore the original state, generating a tendency force to restore the original state. This tendency force will automatically drive the extension plate 609 to retract when the nut 604 moves in the opposite direction. When the foundation pit support structure needs to be renovated, the operator turns the handle 613 in the opposite direction to move the nut 604 in the opposite direction. The tension spring 611 releases the elastic potential energy and drives the extension plate 609 to automatically retract, reducing the manpower consumption required for adjustment and improving construction efficiency and convenience. The provision of the support frame 8 further enhances the connection stability between the steel sheet pile 2 and the waist beam 3. During the foundation pit support process, the steel sheet pile 2 bears the lateral pressure of the soil, and these pressures are transmitted to the waist beam 3 through the steel sheet pile 2. The support frame 8, as a supporting component, effectively shares the pressure transmitted to the waist beam 3 by the steel sheet pile 2. According to the principle of force decomposition and transmission, the pressure concentrated on certain parts of the waist beam 3 is dispersed to a larger area to prevent the waist beam 3 from being deformed or damaged due to uneven force. At the same time, the support frame 8 can also adjust the relative position between the steel sheet pile 2 and the waist beam 3. During the installation process, due to factors such as construction errors, there may be a certain position deviation between the steel sheet pile 2 and the waist beam 3. The support frame 8 can fine-tune this deviation through its own structure and connection method to ensure that the two always maintain a correct connection relationship during installation and use, thereby ensuring the integrity and stability of the entire foundation pit support structure.

[0026] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A foundation pit support structure, comprising a foundation pit (1), characterized in that: A steel sheet pile (2) is installed around the inner wall of the foundation trench (1), one end of the steel sheet pile (2) extends deep into the foundation trench (1), a waist beam (3) is installed on one side of the inner wall of the steel sheet pile (2), a steel pipe (4) is installed inside the waist beam (3), the interior of the foundation trench (1) is filled with a supporting layer (5) for supporting the foundation pit, and an extension mechanism (6) is installed inside the steel pipe (4) for increasing the supporting area of ​​the steel pipe (4).

2. A foundation pit support structure according to claim 1, characterized in that: The supporting layer (5) comprises a backfill layer (501), the backfill layer (501) is filled on the inner bottom wall of the foundation trench (1), a concrete layer (502) is arranged on the top of the backfill layer (501), the concrete layer (502) is wrapped around the outer wall of the steel pipe (4), the outside of the concrete layer (502) is filled with a dense layer (503), and the top of the dense layer (503) is filled with a stone chip layer (504).

3. A foundation pit support structure according to claim 1, characterized in that: The extension mechanism (6) comprises an inner frame (601), wherein the inner frame (601) is respectively mounted at two ends of the inner part of the steel pipe (4), and a driven bevel gear (602) is rotatably connected to one side of the outer wall of the inner frame (601), and one end of a threaded rod (603) is mounted on the outer wall of the driven bevel gear (602), and the other end of the threaded rod (603) passes through the inner frame (601), and a nut (604) is threadedly connected to the outer wall of the threaded rod (603), and the nut (604) and the inner frame are A retractable rod (605) is installed inside (601), one end of an extension rod (606) is installed on one side of the outer wall of the nut (604), and a top cone (607) is installed on the other end of the extension rod (606). A slideway (7) is opened on one side of the outer wall of the steel pipe (4), and a slide groove (608) is opened on the outer wall of the built-in frame (601) on the other side. An extension plate (609) is slidably connected inside the slide groove (608), and one end of the top cone (607) passes through one side of the built-in frame (601).

4. A foundation pit support structure according to claim 3, characterized in that: A positioning block (610) is installed on one side of the outer wall of the extension plate (609), one end of a tension spring (611) is installed on one side of the outer wall of the positioning block (610), and the other end of the tension spring (611) is installed on the inner wall of the steel pipe (4).

5. A foundation pit support structure according to claim 3, characterized in that: A driving bevel gear (612) is rotatably connected to one side of the outer wall of the steel pipe (4), and the driving bevel gear (612) is meshingly connected to the driven bevel gear (602).

6. A foundation pit support structure according to claim 5, characterized in that: A handle (613) is installed on one side of the outer wall of the active bevel gear (612).

7. A foundation pit support structure according to claim 3, characterized in that: One end of the extension plate (609) is fan-shaped.

8. A foundation pit supporting structure according to claim 3, characterized in that: One side of the inner wall of the steel sheet pile (2) is mounted with one side of the outer wall of the support frame (8), and the other side of the outer wall of the support frame (8) is fixedly connected to the bottom of the waist beam (3).

9. A foundation pit support structure according to claim 2, characterized in that: The dense layer (503) is filled to the horizontal top of the steel pipe (4), and the stone chip layer (504) is filled to the horizontal bottom of the waist beam (3).

10. A foundation pit support structure according to claim 2, characterized in that: The backfill layer (501) is made of thick medium-coarse sand, and the filling material of the dense layer (503) is made of medium-coarse sand.

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