Foundation pit support structure and foundation pit support method

Abstract

The present invention relates to the field of building construction structures and processes thereof, and specifically to a foundation pit support structure and a foundation pit support method, wherein the foundation pit support structure comprises a positioning seat, an inner inclined cantilever pile, an outer inclined cantilever pile, a cross support, a water-blocking curtain, and a support pile, wherein the inner inclined cantilever pile and the outer inclined cantilever pile are arranged alternately, and the inner inclined cantilever pile and the outer inclined cantilever pile cross each other to form an X shape, the positioning seat is fixed on the top of the inner inclined cantilever pile and the outer inclined cantilever pile, and the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile is located at the edge of the foundation pit bottom surface, one end of the cross support is fixed on the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile, and the other end is fixed with a support pile extending downward to the bottom of the pit. The cross support provides stable support at the junction of the foundation pit bottom and the side wall to prevent the foundation pit side wall from collapsing, the inner inclined cantilever pile and the outer inclined cantilever pile cross, and the positioning seat is cast on the top, the upper half forms a stable triangular support structure, and the lower half penetrates into the foundation pit bottom, thereby improving the anti-overturning performance of the support structure.

Description

Technical Field

[0001] The present invention relates to the field of building construction structures and processes thereof, and in particular to a foundation pit support structure and a foundation pit support method. Background Art

[0002] Foundation pit support is a measure used to support, reinforce, and protect the sidewalls and surrounding environment of a foundation pit to ensure the safety of underground structure construction and the surrounding environment. The construction of cantilever support piles using reinforced concrete bored cast-in-place pile technology was a common approach in the early days. This method involves mechanically drilling holes to form pile holes, then lowering steel cages and pouring concrete to form piles. These reinforced concrete piles, arranged in columns and spaced apart, serve as a retaining structure. Because cantilever support piles have significant lateral stiffness, they can effectively limit deformation of the support structure. In traditional foundation pit cantilever support structures, the cantilever piles extend deep into the pit bottom. Because the outer sides of the cantilever piles are subjected to pressure from the soil outside the pit, the support points where the cantilever piles meet the pit bottom experience significant pressure, causing the soil at these points to easily collapse inward, leading to the collapse of the cantilever piles and the pit sidewalls. Consequently, traditional cantilever beam support structures have poor stability. Inadequate support can lead to safety hazards such as settlement and tilting of surrounding buildings and pit collapse caused by rising groundwater. This case was initiated in light of these concerns. Summary of the Invention

[0003] An object of the present invention is to solve at least the above-mentioned problems through a foundation pit supporting structure and a foundation pit supporting method.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a foundation pit support structure, characterized in that: it includes a positioning seat, an inner inclined cantilever pile, an outer inclined cantilever pile, a cross support, a water-proof curtain and a support pile, the inner inclined cantilever piles and the outer inclined cantilever piles are arranged alternately, and the inner inclined cantilever piles and the outer inclined cantilever piles are crossed with each other in an X shape, the positioning seat is fixed on the top of the inner inclined cantilever pile and the outer inclined cantilever pile, and the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile is located at the edge of the bottom of the foundation pit, one end of the cross support is fixed on the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile, and the other end is fixed with a support pile extending to the bottom of the pit, and the water-proof curtain extends downward from the middle of the cross support to the bottom of the pit.

[0005] Preferably, the inner inclined cantilever piles are inclined from top to bottom toward the outside of the foundation pit, and the outer inclined cantilever piles are inclined from top to bottom toward the inside of the foundation pit.

[0006] Preferably, the angle between the inner inclined cantilever pile and the vertical plane is 15-22 degrees, and the angle between the outer inclined cantilever pile and the vertical plane is 15-22 degrees.

[0007] Preferably, the top surface of the cross support is flush with the bottom surface of the foundation pit, and the end of the cross support is connected to the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile by pouring concrete.

[0008] Preferably, the waterproof curtain is formed by continuous casting of high-pressure rotary jet piles, and the inner inclined cantilever piles are provided with a backfill layer toward the side of the foundation pit, and the backfill layer is covered with a waterproof reinforced concrete layer.

[0009] Preferably, the inner inclined cantilever piles, the outer inclined cantilever piles and the supporting piles are all bored cast-in-place piles.

[0010] Preferably, a steel frame and an inclined steel sleeve are provided inside the positioning seat, the inner inclined cantilever piles and the outer inclined cantilever piles are drilled and cast through the inclined steel sleeve, and a concrete foundation is provided at the bottom of the positioning seat.

[0011] Preferably, a downpipe is provided on the cross support, and the downpipe is located on the side of the supporting pile close to the foundation pit. The downpipe includes a downpipe, the bottom of the downpipe is conical, the lower side wall of the downpipe is provided with a water-permeable hole, a sand and gravel filter layer is provided in the lower part of the downpipe, an inner sleeve is embedded in the sand and gravel filter layer, the side wall of the inner sleeve is provided with a through hole, the outer wall of the inner sleeve is covered with geotextile, a steel mesh is provided on the top of the inner sleeve, a water pump is provided above the steel mesh, and the water pump is connected to the outside through a water pipe.

[0012] The supporting method of the foundation pit supporting structure is characterized by comprising the following steps:

[0013] Step a: Mark the outer edge of the foundation pit, pour a concrete foundation on the bottom surface at the edge of the foundation pit, set a pre-buried steel skeleton on the concrete foundation, fix the inclined steel sleeve on the steel skeleton at a set angle, and then pour the positioning seat;

[0014] Step b, using the inclined steel sleeve as a guide hole, drilling downward and pouring piles to form cross-arranged inner-slanted cantilever piles and outer-slanted cantilever piles;

[0015] Step c: dig the foundation pit down to the bottom of the pit, and continue to dig out space for pouring cross supports based on the bottom of the pit, and form support piles by drilling and pouring, and continuously pour into a water-proof curtain by high-pressure jet grouting piles;

[0016] Step d: Cast a cross support on top of the support piles and the water-blocking curtain, with one side of the cross support connected to the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile;

[0017] Step e: backfill soil on the inner inclined cantilever pile toward one side of the foundation pit, and cover the backfill soil layer with a waterproof reinforced concrete layer.

[0018] Preferably, in step c, the cross support is cast to embed the vertical steel sleeve, and in step e, a hole is drilled in the vertical steel sleeve outside the water-proof reinforced concrete layer and the downcomer is embedded.

[0019] From the above description, it can be seen that the foundation pit support structure and foundation pit support method provided by the present invention have the following beneficial effects: the inner inclined cantilever piles and the outer inclined cantilever piles are crossed with each other to form an X shape, and a cross support is cast at the intersection. The bottom of the cross support is supported by a water-proof curtain and support piles. The cross support provides stable support at the junction of the bottom and side wall of the foundation pit to avoid the collapse of the side wall of the foundation pit. The inner inclined cantilever piles and the outer inclined cantilever piles are crossed, and a positioning seat is cast on the top. The upper part forms a stable triangular support structure, and the lower part The waterproof curtain is located below the pit bottom, and a waterproof reinforced concrete layer is provided above the pit bottom. The two layers are used together to block groundwater from entering the pit through the side walls of the pit, thereby preventing settlement of the pit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the foundation pit supporting structure of the present invention.

[0021] Figure 2 This is a structural diagram of the downpipe. DETAILED DESCRIPTION

[0022] The present invention is further described below through specific embodiments.

[0023] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0024] like Figure 1As shown, the foundation pit support structure of the present invention includes a positioning seat 1, an inner inclined cantilever pile 2, an outer inclined cantilever pile 3, a cross support 4, a water-proof curtain 5 and a support pile 6. The inner inclined cantilever piles 2 and the outer inclined cantilever piles 3 are arranged alternately, and the inner inclined cantilever piles 2 and the outer inclined cantilever piles 3 are crossed with each other to form an X shape. The positioning seat 1 is fixed on the top of the inner inclined cantilever pile 2 and the outer inclined cantilever pile 3. The intersection of the inner inclined cantilever pile 2 and the outer inclined cantilever pile 3 is located at the edge of the bottom of the foundation pit. One end of the cross support 4 is fixed on the intersection of the inner inclined cantilever pile 2 and the outer inclined cantilever pile 3, and the other end is fixed with a support pile 6 extending to the bottom of the pit. The water-proof curtain 5 extends downward from the middle of the cross support 4 to the bottom of the pit. The inwardly inclined cantilever piles 2 and the outwardly inclined cantilever piles 3 cross each other in an X shape, and a cross support 4 is cast at the intersection. The bottom of the cross support 4 is supported by a waterproof curtain 5 and support piles 6. The cross support 4 provides stable support at the junction of the bottom and side walls of the foundation pit to prevent the side walls of the foundation pit from collapsing. The inwardly inclined cantilever piles 2 and the outwardly inclined cantilever piles 3 cross, and a positioning seat 1 is cast on the top. The upper part forms a stable triangular support structure, and the lower part penetrates into the bottom of the foundation pit to improve the anti-overturning performance of the support structure; the waterproof curtain 5 mainly functions to isolate water, and the support and pressure bearing of the foundation pit are completed by the inwardly inclined cantilever piles 2 and the outwardly inclined cantilever piles 3. Therefore, the waterproof curtain 5 will not bear too much pressure around the foundation pit, greatly reducing the pressure cracking of the waterproof curtain 5.

[0025] The inner-slanted cantilever piles 2 are tilted downward toward the outside of the foundation pit, while the outer-slanted cantilever piles 3 are tilted downward toward the inside of the foundation pit. The inner-slanted cantilever piles 2 and the outer-slanted cantilever piles 3 intersect each other in an X shape, with the intersection being flush with the bottom of the foundation pit. Since the positioning seat 1 is cast on top of the inner-slanted cantilever piles 2 and the outer-slanted cantilever piles 3, the positioning seat 1 and the upper half of the inner-slanted cantilever piles 2 and the outer-slanted cantilever piles 3 form a triangular stable structure with good support stability. The inner-slanted cantilever piles 2 and the outer-slanted cantilever piles 3 extend downward below the bottom of the foundation pit, giving the entire support mechanism good anti-overturning performance.

[0026] The included angle between the inner inclined cantilever pile 2 and the vertical plane is 15-22 degrees, and the included angle between the outer inclined cantilever pile 3 and the vertical plane is 15-22 degrees.

[0027] The top surface of the cross support 4 is flush with the bottom surface of the foundation pit, and the end of the cross support 4 is connected to the intersection of the inner inclined cantilever pile 2 and the outer inclined cantilever pile 3 by pouring concrete.

[0028] The waterproof curtain 5 is formed by continuous pouring of high-pressure rotary jet piles. The inner inclined cantilever piles 2 are provided with a backfill layer 7 toward the side of the foundation pit, and the backfill layer 7 is covered with a waterproof reinforced concrete layer 8. The continuous waterproof curtain 5 is located below the ground at the bottom of the pit, and a waterproof reinforced concrete layer 8 is provided above the bottom of the pit. The two together are used to prevent groundwater outside the foundation pit from entering the interior of the foundation pit through the side walls of the foundation pit, thereby preventing internal settlement of the foundation pit. The side walls of the foundation pit are supported by the cross-arranged inner inclined cantilever piles 2 and outer inclined cantilever piles 3. Therefore, the waterproof curtain 5 and the waterproof reinforced concrete layer 8 only serve as water barriers, and are not used for support and pressure bearing, so they are not easily damaged by pressure. The angle between the backfill layer 7 and the waterproof reinforced concrete layer 8 and the vertical plane is 5-15 degrees.

[0029] The inner inclined cantilever pile 2, the outer inclined cantilever pile 3 and the supporting pile 6 are all bored cast-in-place piles.

[0030] The interior of the locating base 1 is equipped with a steel skeleton and an inclined steel sleeve 11. The inner and outer inclined cantilever piles 2 and 3 are drilled and cast through the inclined steel sleeve 11. A concrete foundation 12 is provided at the bottom of the locating base 1. The inclined steel sleeve 11 provides angular positioning for the subsequent inner and outer inclined cantilever piles 2 and 3, improving the accuracy of the casting.

[0031] A downpipe 9 is provided on the cross support 4 and is located on the side of the support pile 6 close to the foundation pit. Figure 2 The downpipe 9 includes a downpipe 91. The bottom of the downpipe 91 is conical. The lower sidewall of the downpipe 91 is provided with a water-permeable hole. The lower part of the downpipe 91 is provided with a sand and gravel filter layer 92. The sand and gravel filter layer 92 is embedded with an inner sleeve 93. The sidewall of the inner sleeve 93 is provided with a through hole. The outer wall of the inner sleeve 93 is covered with a geotextile 94. The top of the inner sleeve 93 is provided with a steel mesh. A water pump 95 is provided above the steel mesh. The water pump 95 is connected to the outside through a water pipe. The downpipe 9 is used to dewater the interior of the foundation pit to prevent the collapse and settlement of the sidewalls of the foundation pit. The water at the bottom of the foundation pit enters the downpipe 91 through the water-permeable hole, and enters the inner sleeve 93 after being filtered by the sand and gravel filter layer 92 and the geotextile 94. Finally, it is pumped out by the water pump 95, thereby effectively controlling the water level at the bottom of the foundation pit, avoiding the collapse of the foundation pit caused by the technology, and improving the stability of the foundation pit support.

[0032] The supporting method of the foundation pit supporting structure includes the following steps:

[0033] Step a: Mark the outer edge of the foundation pit, pour a concrete foundation 12 on the bottom surface at the edge of the foundation pit, set a pre-buried steel skeleton on the concrete foundation 12, and fix the inclined steel sleeve 11 on the steel skeleton at a set angle, and then pour the positioning seat 1;

[0034] Step b: using the inclined steel sleeve 11 as a guide hole, drilling downwards and pouring piles to form cross-arranged inner inclined cantilever piles 2 and outer inclined cantilever piles 3;

[0035] Step c, dig the foundation pit downward to the bottom of the pit, continue to dig downward to cast the cross support 4 based on the bottom of the pit, form the support piles 6 by drilling and pouring, and continuously cast the waterproof curtain 5 by high-pressure rotary grouting piles, and the waterproof curtain 5 extends downward to the bottom of the outer inclined cantilever pile 3;

[0036] Step d: Cast a cross support 4 on top of the support pile 6 and the water-blocking curtain 5, and connect one side of the cross support 4 to the intersection of the inner inclined cantilever pile 2 and the outer inclined cantilever pile 3;

[0037] Step e: backfill soil on the inner inclined cantilever pile 2 toward one side of the foundation pit, and cover the backfill soil layer 7 with a waterproof reinforced concrete layer 8.

[0038] In step c, the cross support 4 is cast to embed the vertical steel sleeve. In step e, a hole is drilled in the vertical steel sleeve outside the water-proof reinforced concrete layer 8 and the downcomer 9 is embedded.

[0039] The above are only some specific implementation methods of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. Foundation pit support structure, characterized by: It includes a positioning seat, an inner inclined cantilever pile, an outer inclined cantilever pile, a cross support, a water-proof curtain and a supporting pile. The inner inclined cantilever pile and the outer inclined cantilever pile are arranged alternately, and the inner inclined cantilever pile and the outer inclined cantilever pile are crossed to form an X shape. The positioning seat is fixed on the top of the inner inclined cantilever pile and the outer inclined cantilever pile. The intersection of the inner inclined cantilever pile and the outer inclined cantilever pile is located at the edge of the bottom of the foundation pit. One end of the cross support is fixed on the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile, and the other end is fixed with a supporting pile extending to the bottom of the pit. The water-proof curtain extends downward from the middle of the cross support to the bottom of the pit. The cross support is provided with a downpipe, which is located on the side of the supporting pile close to the foundation pit. The downpipe includes a downpipe, the bottom of the downpipe is conical, and the lower side wall of the downpipe is provided with a water-permeable Hole, a sand and gravel filter layer is provided in the lower part of the precipitation steel pipe, an inner sleeve is embedded in the sand and gravel filter layer, the side wall of the inner sleeve is provided with a through hole, the outer wall of the inner sleeve is covered with geotextile, a steel mesh is provided on the top of the inner sleeve, a water pump is provided above the steel mesh, the water pump is connected to the outside through a water pipe, the top surface of the cross support is flush with the bottom surface of the foundation pit, the end of the cross support is connected to the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile by pouring concrete, the water-proof curtain is formed by continuous pouring of high-pressure rotary jet piles, the inner inclined cantilever pile is provided with a backfill layer toward the side of the foundation pit, the backfill layer is covered with a water-proof reinforced concrete layer, a steel skeleton and an inclined steel sleeve are provided inside the positioning seat, the inner inclined cantilever pile and the outer inclined cantilever pile are drilled and cast through the inclined steel sleeve, and a concrete foundation is provided at the bottom of the positioning seat.

2. The foundation pit supporting structure according to claim 1, characterized in that: The inner inclined cantilever piles are inclined from top to bottom toward the outside of the foundation pit, and the outer inclined cantilever piles are inclined from top to bottom toward the inside of the foundation pit.

3. The foundation pit supporting structure according to claim 1, characterized in that: The included angle between the inner inclined cantilever pile and the vertical plane is 15-22 degrees, and the included angle between the outer inclined cantilever pile and the vertical plane is 15-22 degrees.

4. The foundation pit supporting structure according to claim 1, characterized in that: The inner inclined cantilever piles, outer inclined cantilever piles and supporting piles are all bored cast-in-place piles.

5. The supporting method for a foundation pit supporting structure according to any one of claims 1 to 4, characterized in that: The steps include: Step a: Mark the outer edge of the foundation pit, pour a concrete foundation on the bottom surface at the edge of the foundation pit, set a pre-buried steel skeleton on the concrete foundation, fix the inclined steel sleeve on the steel skeleton at a set angle, and then pour the positioning seat; Step b, using the inclined steel sleeve as a guide hole, drilling downward and pouring piles to form cross-arranged inner-slanted cantilever piles and outer-slanted cantilever piles; Step c: dig the foundation pit down to the bottom of the pit, and continue to dig out space for pouring cross supports based on the bottom of the pit. Form support piles by drilling and pouring, and continuously pour into a water-proof curtain by high-pressure jet grouting piles. Step d: Cast a cross support on top of the support piles and the water-blocking curtain, with one side of the cross support connected to the intersection of the inner inclined cantilever pile and the outer inclined cantilever pile; Step e: backfill soil on the inner inclined cantilever pile toward one side of the foundation pit, and cover the backfill soil layer with a waterproof reinforced concrete layer.

6. The supporting method of the foundation pit supporting structure according to claim 5, characterized in that: In the step c, the cross supports are cast and the vertical steel sleeves are embedded. In the step e, holes are drilled in the vertical steel sleeves outside the water-proof reinforced concrete layer and the downcomers are embedded.

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