CN115595986A - A foundation pit enclosure structure and construction method - Google Patents

Abstract

The invention discloses a foundation pit support structure and a construction method, wherein the foundation pit support structure comprises a foundation pit, a plurality of fender posts are uniformly arranged at intervals around the foundation pit, the tops of the fender posts are fixedly connected through crown beams, a plurality of groups of supporting components are arranged in the foundation pit, the supporting components are supported on one side of the fender posts, and the supporting components are connected into a whole through connecting beams; the bottom of the supporting component penetrates through the reinforcement cushion component and is embedded and inserted in the deep part of the soil layer; a construction method of a foundation pit support structure comprises the steps of fender pile construction, first support construction, first subsoil excavation, second subsoil excavation and foundation pit backfilling. The structure is stable and reliable, the foundation pit excavation device is suitable for excavation of foundation pits of various specifications, particularly suitable for reduction of construction deformation of deeper foundation pits, part of the structure can be recycled, construction of the foundation pit enclosure structure and construction of the building structure in the pit are organically combined in the whole construction process, the whole foundation pit construction process is safe and orderly, and the construction period is short.

Description

A foundation pit enclosure structure and construction method

technical field

The invention relates to the technical field of underground engineering construction, in particular to a foundation pit enclosure structure and a construction method.

Background technique

With the continuous development and construction of the city, the foundation pit project is gradually developing in a deep and general direction, and the construction environment is becoming more and more complex. For large-area deep foundation pit projects, support or pile-anchor systems are often used in engineering practice. When the excavation area of the foundation pit is large, the support system often needs to be constructed in separate pits due to the large slenderness ratio of the support, which will inevitably affect the construction period. At the same time, the setting of the internal support system also has a lot of restrictions on excavation; the pile-anchor system often needs to occupy the space outside the site, which has a great impact on the surrounding environment. There are many restrictions in urban construction, so this The two systems often have certain limitations in engineering applications. Foundation pit engineering is generally an underground temporary structure. How to adopt a reasonable enclosure support system on the basis of ensuring safety and comprehensively considering factors such as economy and construction period is a problem that should be considered in the design of foundation pit engineering.

After retrieval, it was found that the Chinese patent application number CN 106013172 B discloses a soft soil deep foundation pit support structure and construction method combined with double-row piles and diagonal braces. Set the bottom support pier to transfer the support force to the bottom plate. Although the patent uses diagonal braces, the diagonal braces do not penetrate deep into the soil layer, so the ability to control deformation is poor. At the same time, when the patent is constructed, the soil needs to be left behind and the bottom plate needs to be constructed twice, which has a great impact on the construction period. , and if there is a building beside the pit, the construction of the foundation pit will be more difficult.

The application number is the Chinese patent of CN 211922637 U, discloses a kind of A-shaped double-row pile foundation pit support with diagonal bracing between the piles, this patent enclosure structure mainly adopts the front row of piles as the enclosure structure, and the rear row of piles as the For the support structure, the front and rear rows of piles are set with diagonal braces between piles. Since the front row of piles is a single pile, the stability and deformation resistance of the enclosure structure are poor, so it is often suitable for shallow foundation pits on the ground floor. At the same time, the diagonal braces between piles are only Supporting to the center of the rear row of piles is likely to cause engineering risks such as breaking of the rear row of piles, and the rear row of piles needs to pass through the structural bottom plate, which requires high waterproofing of the bottom plate.

The application number is the Chinese patent of CN 114197483 A, which discloses a foundation pit enclosure structure and a construction method thereof. The invention includes a plurality of upright columns, grouting slant pipes and connecting slant pipes. By setting jacks in the crown beam, ordinary slant pipes are movably connected in the sockets. Mechanism, there is an adjustment mechanism between the grouting slant pipe and the connecting slant pipe, and the top of the grouting slant pipe is movably connected with a rotating pipe, which solves the problem that the grouting slant pipe slant bracing combination structure used in the prior art cannot be actively The problem of controlling the deformation of the foundation pit and the inability to recover the fixed connection of the diagonal braces increases the cost of the structure. However, this invention does not solve the problems of the relationship between the grouted diagonal braces and the main underground structure.

To sum up, the existing support forms for similar foundation pits mainly use two combinations of double-row piles + diagonal braces or single-row piles + diagonal braces. These two types of enclosures have certain limitations: double-row piles +In the combination of diagonal braces, the diagonal braces are generally supported to the bottom plate, and the soil needs to be excavated after leaving the side of the pit. The bottom plate needs to be constructed twice, which has a great impact on the construction period. At the same time, the diagonal braces are braced to the bottom plate, so the force transmission is poor and the deformation of the foundation pit is controlled. The effect is poor, and there is a certain limit to the excavation depth of the foundation pit; in the combination of single-row piles and diagonal braces, the deformation control ability and stability of the single-row piles are poor, and the diagonal braces need to pass through the bottom plate, which requires high waterproofing of the bottom plate. It is also suitable for shallow foundation pits.

Contents of the invention

The object of the present invention is to provide a foundation pit enclosure structure and construction method. The structure is fixedly connected into a whole in the foundation pit, and comprehensively solves the waterproof problem of the foundation pit. The enclosure process is stable and reliable, and is suitable for foundation pits of various specifications. Excavation is especially suitable for reducing the construction deformation of deep foundation pits. During the entire construction process, the construction of the foundation pit enclosure structure and the construction of the building structure in the pit are organically combined, so that the entire foundation pit project can be carried out safely and orderly.

To achieve the above object, the present invention takes the following technical solutions:

An enclosure structure for a foundation pit, comprising a foundation pit, a number of enclosure piles are evenly spaced around the foundation pit, the tops of the several enclosure piles are fixedly connected by crown beams, and several groups of support components are arranged in the foundation pit, and the support assemblies are supported on On the side of the retaining pile, the supporting components are connected into a whole through the connecting beam; the reinforced cushion component is arranged around the bottom of the foundation pit, and the bottom of the supporting component passes through the reinforced cushion component and is buried deep in the soil layer;

The support assembly includes a first support between the crown beam and the bottom of the foundation pit. The first support is arranged correspondingly to the surrounding protection piles. Diagonal bracing pipe, the bottom of the diagonal bracing pipe is provided with a pouring head, the top of the diagonal bracing pipe is anchored at the crown beam, and the bottom of the diagonal bracing pipe is buried deep in the soil layer; The supporting beams in between, the steel columns whose tops are supported at the bottom of the supporting beams, and the bottom ends of the steel columns are buried deep in the soil layer;

The reinforcement cushion component includes a reinforcement cushion and a plurality of inserted bars arranged at even intervals at the bottom of the reinforcement cushion. The reinforcement cushion is made of double-sided two-way reinforcement and concrete pouring, and the reinforcement cushion is laid on the bottom of the foundation pit The surrounding area and the soil layer at the bottom of the foundation pit are inserted through inserting reinforcement.

Preferably, several vertical water stop piles are arranged between the surrounding protection piles and the side wall of the foundation pit.

Preferably, several anchor bars are arranged around the top of the diagonal brace, and the anchor bars are bound together with the steel bar structure in the crown beam.

Preferably, one end of the supporting beam is fixedly connected to the surrounding protection piles through double-split purlins, and the other end of the supporting beam is fixedly connected to the diagonal bracing pipe.

Preferably, the double purlin is a quadrilateral structure made of I-beam, channel steel or steel plate; the supporting beam is a rod-shaped structure made of round steel pipe or square steel pipe.

Preferably, the connecting beam is made of I-shaped steel or channel steel, and the connecting beam is connected between two adjacent supporting beams.

Preferably, the upper side of the reinforced cushion assembly is provided with a building structure in the pit, the building structure in the pit includes a bottom plate, the building structure in the pit is connected with the surrounding piles through a force transmission belt, and the diagonal bracing pipe is inclined through the building structure in the pit and The reinforced cushion component is buried deep in the soil layer, and a water-stop steel plate is arranged at the intersection of the diagonal bracing pipe and the middle of the bottom plate.

Preferably, one end of the force transmission belt is pre-buried and poured on one side of the building structure in the pit, and the other end of the force transmission belt is anchored in the surrounding protection pile; The main body is set on the upper part of the reinforced cushion assembly, one end of the power transmission belt of the bottom slab is pre-buried and poured on one end of the bottom slab, and the other end of the power transmission belt of the bottom slab is anchored into the surrounding protection pile; The side is welded to the main reinforcement of the surrounding protection pile through hanging ribs; the force transmission belt of the middle floor is arranged in the first support gap and arranged at equal intervals along the periphery of the foundation pit.

A construction method for a foundation pit enclosure structure, comprising the following steps:

Step 1, the construction of the enclosure piles, according to the drawings, surveying and setting out, marking and positioning the locations of the enclosure piles and vertical water-stop piles on site, and completing the construction of the enclosure piles and vertical water-stop piles;

Step 2, the first support construction, after statically pressing the diagonal support pipe to the specified depth in the soil layer, pour graded gravel into the diagonal support pipe first, and then pour pure cement into the diagonal support pipe to the top of the diagonal support pipe, A number of anchor bars are evenly connected by welding around the top of the diagonal brace pipe, and the anchor bars are bound and poured to the steel structure in the crown beam;

Step 3: Excavate the first surface soil, excavate the soil layer by layer and block to the design position of the supporting beam, erect several groups of second supports, and connect the adjacent second supports through the connecting beams. All the first supports in the foundation pit The two supports are connected into a whole;

Step 4: Excavate the second skin and soil, excavate layer by block to the bottom of the foundation pit, construct reinforcement cushion components, and then construct the bottom plate and bottom plate power transmission belt, and install water-stop steel plates at the intersection of the middle of the bottom plate and the diagonal bracing pipe , after the strength of the bottom slab and the force transmission belt of the bottom slab meets the requirements, remove the connecting beam and the second support; continue to construct the mid-floor and mid-floor force One end is cut flush along the top surface of the bottom plate, and the other end is cut flush along the side of the surrounding pile;

Step 5: backfill the foundation pit, fill the building structure in the construction pit to positive and negative zero, and backfill the foundation pit.

In the present invention, the foundation pit enclosure structure is fixedly connected into a whole by several sets of support components, the whole structure is stable and reliable, improves the safety of the foundation pit enclosure, has low requirements on the construction environment, and is suitable for foundation pits of various specifications Excavation, especially suitable for reducing construction deformation of deep foundation pits;

The first support includes diagonal bracing tubes. The diagonal bracing tubes can not only play a supporting role, but also serve as a pouring channel after the diagonal bracing tubes are in place. Gradated gravel and pure cement are poured into the diagonal bracing tubes from the top of the diagonal bracing tubes. The pouring head is formed at the bottom of the diagonally braced pipe to increase the contact area between the first support and the soil layer, so as to increase the connection strength and prevent subsidence. Compared with prefabricated concrete piles, it is more economical and the diagonally braced pipe part can be recycle and re-use;

The second support is installed between the first support and the surrounding protection pile, which increases the supporting strength of the first support, prevents the deformation of the first support, reduces the deformation of the side wall of the foundation pit, and improves the safety of the entire foundation pit enclosure structure and reliability;

The reinforcement cushion components are arranged around the bottom of the foundation pit, which can effectively reduce the deformation of the bottom when the foundation pit is excavated to the bottom;

A number of vertical water stop piles are set between the retaining pile and the side wall of the foundation pit to play the role of waterproof and soil retaining;

The construction method of the foundation pit enclosure structure is organically combined with the excavation of the foundation pit and the construction of the building structure in the pit, the excavation of the foundation pit is not restricted, the construction process is simple, the construction period is short and the economy is good.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention;

Fig. 2 is a top view of the overall structure of the present invention;

Fig. 3 is the welding schematic diagram between support assembly and connecting beam of the present invention;

Fig. 4 is the schematic diagram of the connection between the brace pipe and the crown beam of the present invention;

Fig. 5 is a schematic diagram of welding between the supporting beam and the brace pipe of the present invention;

Fig. 6 is the welding schematic diagram between support beam and steel column of the present invention;

Fig. 7 is the schematic diagram that is provided with the building structure in the pit on the overall structure of the present invention;

Fig. 8 is a schematic diagram of the connection between the building structure in the pit and the retaining piles;

Figure 9 is a schematic diagram of the installation of water-stop steel plates;

Figure 10 is a construction schematic diagram corresponding to step 1;

Figure 11 is a construction schematic diagram corresponding to step 2;

Figure 12 is a construction schematic diagram corresponding to step three;

Figure 13 is one of the construction schematic diagrams corresponding to step four;

Figure 14 is the second construction schematic diagram corresponding to step four;

Figure 15 is the third construction schematic diagram corresponding to step four;

Figure 16 is a construction diagram corresponding to step five.

In the figure: 1. Surrounding piles; 2. Support components; 3. Building structure in the pit; 4. Reinforced cushion components; 5. Force transmission belt; 6. Connecting beams; 10. Crown beams; Pile; 20. First support; 21. Second support; 30. Waterproof steel plate; 31. Bottom plate; 40. Reinforcement cushion; 41. Inserting ribs; ; 200, diagonal bracing pipe; 201, pouring head; 210, supporting beam; 211, steel column;

detailed description

Below in conjunction with accompanying drawing, the present invention will be further described:

Embodiment one:

A foundation pit enclosure structure as shown in Fig. 1 and Fig. 2 includes a foundation pit, and several surrounding protection piles 1 are evenly spaced around the foundation pit, and the tops of several surrounding protection piles 1 are fixedly connected by crown beams 10, and the surrounding The protection pile 1 is cast-in-situ pile, and the pile diameter, pile length and reinforcement of the cast-in-situ pile are determined by calculation. There are several groups of supporting components 2 arranged in the foundation pit. The supporting components 2 are supported on one side of the retaining pile 1. The supporting components 2 are connected into a whole through the connecting beam 6. The interaction between the supporting components will generate supporting force and pulling force, preventing a single The support assembly 2 is toppled, which improves the stability of the support assembly 2 and increases the reliability of foundation pit enclosure support. As shown in Figure 3, the support assembly 2 and the connecting beam 6 are connected by welding, and the connecting beam 6 is connected Between two adjacent supporting beams 210 , the connecting beam 6 is made of I-beam or channel steel during specific implementation. A reinforced cushion assembly 4 is arranged around the bottom of the foundation pit. The bottom of the support assembly 2 passes through the reinforced cushion assembly 4 and is buried deep in the soil layer. The reinforced cushion assembly 4 includes a reinforced cushion 40 and uniformly spaced Multiple inserted bars 41 at the bottom of the reinforcement cushion 40, the reinforcement cushion 40 is made of double-sided two-way reinforcement and concrete pouring, the concrete used for the reinforcement cushion 40 is not less than C30, and the built-in C12@200 double-sided two-way reinforcement C12 steel bars are used for the inserted bars, the length is 1500mm, and the interval between the inserted bars is 1m. The inserted bars are anchored into the reinforcement cushion 150mm deep. The bottom soil layer is plugged.

The support assembly 2 includes a first support 20 diagonally braced between the crown beam 10 and the bottom of the foundation pit, the first support 20 is arranged corresponding to the surrounding protection pile 1, and the angle between the first support 20 and the surrounding protection pile 1 is greater than 35°, The first support 20 is in contact with the surrounding protection pile 1, and the second support 21 is supported. The first support 20 includes a slanting tube 200. The slanting tube 20 can be selected from a round steel tube or a square steel tube. To support the role of support, after the diagonal brace 200 is in place, it also serves as a pouring channel, pouring graded crushed stone and pure cement into the diagonal brace 200 from the top of the diagonal brace 200, forming a pouring head at the bottom of the diagonal brace 200, to Increase the contact area between the first support and the soil layer to achieve the purpose of increasing the connection strength and preventing subsidence. Compared with prefabricated concrete piles, it is more economical and part of the diagonal brace 200 can be recycled. The top of the diagonal brace 200 Anchored at the crown beam 10, in a more optimal embodiment, as shown in Figure 4, several anchor bars are arranged around the top of the diagonal brace 200, and the anchor bars are bound together with the steel structure in the crown beam 10, so In actual implementation, the first support 20 and the crown beam 10 are poured at the same time, and the bottom of the diagonal support pipe 200 is buried deep in the soil layer; the second support 21 includes a support beam abutted between the surrounding protection pile 1 and the first support 20 210. The top is supported on the steel column 211 at the bottom of the support beam 210, as shown in Figure 5 and Figure 6, the support beam 210 is welded to the diagonal brace pipe 200, and the support beam 210 is welded to the steel column 211, and the thickness of the weld is uniform Not less than 10mm, the bottom of the steel column 211 is buried deep in the soil layer.

Example 2

A foundation pit enclosure structure as shown in Figure 1 and Figure 2, several vertical water stop piles 11 are arranged between the enclosure pile 1 and the side wall of the foundation pit to play the role of waterproof and soil retaining, vertical The water stop pile 11 is a three-axis stirring pile, and the three-axis stirring pile is sleeved with a hole, and the pile bottom elevation is below 7m at the bottom of the foundation pit.

In this example, one end of the supporting beam 210 is fixedly connected to the enclosure pile 1 through a double-folded purlin 212, and the other end of the supporting beam 210 is fixedly connected to the diagonal bracing pipe 200 by welding. , steel plate or other shaped steel made of quadrilateral structure, specifically, choose (dimensions: height×width×web thickness×flange thickness) 2H700×300×13×24 shaped steel, made of two double pieces, double piece around One end of the purlin 212 is pre-buried and poured on one side of the enclosure pile 1, and the other end of the double-split enclosure 212 is fixedly connected to the support beam 210 by welding. The support beam 210 is a rod-shaped structure made of a round steel pipe or a square steel pipe. Specifically, the support The beam 210 is a circular steel pipe with a diameter of 609 mm and a wall thickness of 16 mm.

As shown in Figures 7 and 8, the upper side of the reinforced cushion assembly 4 is provided with a building structure 3 in the pit, the building structure 3 in the pit includes a bottom plate 31, and the building structure 3 in the pit is connected to the enclosure pile 1 through a force transmission belt 5, the said The diagonal bracing pipe 200 passes through the building structure 3 and the reinforced cushion assembly 4 in the pit in turn and is buried deep in the soil layer. A water-stop steel plate 30 is provided at the intersection of the diagonal bracing pipe 200 and the middle of the bottom plate 31, as shown in FIG. 9 , the diagonal bracing pipe 200 passes through the water-stop steel plate 300, the outer wall of the diagonal bracing pipe 200 is welded with the water-stop steel plate 300, one end of the power transmission belt 5 is pre-buried and poured on the side of the building structure 3 in the pit, and the other end of the power transmission belt 5 is anchored Fence pile 1. The power transmission belt 5 includes a base plate power transmission belt 50 and a middle floor power transmission belt 51. The main body of the base plate power transmission belt 50 is arranged on the upper part of the reinforcement cushion assembly 4. One end of the bottom plate power transmission belt 50 is pre-buried and poured on one end of the bottom plate 31. The bottom plate transmission belt The other end of the force belt 50 is anchored into the surrounding protection pile 1, and the force transmission belt 51 of the middle floor is poured at the same time as the middle floor. The main reinforcement is welded, and the force transmission belt 51 of the middle floor is arranged in the gap of the first support 20 and arranged at equal intervals along the periphery of the foundation pit.

A construction method for a foundation pit enclosure structure, comprising the following steps:

Step 1, the construction of the enclosure pile 1, as shown in Figure 10, according to the drawings and surveying and setting out, mark and locate the location of the enclosure pile 1 and the vertical water stop pile 11 on site, and complete the enclosure pile 1, the crown beam 10 and the vertical Construction of water stop pile 11;

Step 2, construction of the first support 20, as shown in Figure 11, after the diagonal brace 200 is statically pressed to the specified depth in the soil layer, the graded gravel is poured into the diagonal brace 200 first, and then the diagonal brace 200 is poured into the diagonal brace 200 200 pours pure cement to the top of the brace pipe 200, the top of the brace pipe 200 is evenly connected with a number of anchor bars by welding, and the anchor bars are tied to the steel structure in the crown beam 10 and connected by pouring;

Step 3, excavation of the first skin soil, as shown in Figure 12, excavate the soil layer in layers and blocks to the design position of the support beam 210, erect several groups of second supports 21, and connect the adjacent second supports 21 through the connecting beam 6 21 are fixedly connected, and all the second supports 21 in the foundation pit are connected into a whole. In this example, the steel column 211 and the connecting beam 6 are all selected with a specification of (dimensions: height×width×web thickness×flange thickness) H400 ×400×13×21 I-beam;

Step 4, excavation of the second leather soil, as shown in Figure 13 and Figure 14, excavated layer by block to the bottom of the foundation pit, construction of the reinforcement cushion component 4, and then the construction of the bottom plate 31 and the bottom plate force transmission belt 50, the bottom plate Set the waterproof steel plate 30 at the intersection of the middle part of 31 and the diagonal bracing pipe 200; after the bottom plate 31 and the bottom plate force transmission belt 50 reach 80% of the design strength, remove the connecting beam 6 and the second support 21, and continue the construction of the middle floor and the middle floor The force transmission belt 51, after the middle floor and the middle floor force transmission belt 51 reach 80% of the design strength, one end of the diagonal brace pipe 200 is cut off along the top surface of the bottom plate 31, and the other end is cut off along the side of the enclosure pile 1;

Step five, foundation pit backfilling, as shown in Figure 16, the building structure 3 in the construction pit is filled to plus or minus zero, and the foundation pit is backfilled.

The above-mentioned embodiments are only some illustrations of the conception and realization of the present invention, and are not intended to limit it. Under the conception of the present invention, technical solutions without substantial changes are still within the scope of protection.

Claims (9)

1. The utility model provides a foundation pit retaining structure, includes the foundation pit, and the foundation pit is provided with a plurality of fender pile (1) at even interval all around, and a plurality of fender pile (1) tops are through guan liang (10) fixed connection, its characterized in that: a plurality of groups of supporting components (2) are arranged in the foundation pit, the supporting components (2) are supported on one side of the fender post (1), and the supporting components (2) are connected into a whole through connecting beams (6); the bottom of the foundation pit is provided with a reinforcement cushion component (4) around, and the bottom of the supporting component (2) penetrates through the reinforcement cushion component (4) and is embedded in the deep part of the soil layer;

the supporting component (2) comprises a first support (20) which is obliquely supported between the top beam (10) and the bottom of the foundation pit, the first support (20) is arranged corresponding to the fender post (1), and a second support (21) is abutted and supported between the first support (20) and the fender post (1); the first support (20) comprises an inclined supporting pipe (200), a pouring head (201) is arranged at the bottom of the inclined supporting pipe (200), the top end of the inclined supporting pipe (200) is anchored at the crown beam (10), and the bottom of the inclined supporting pipe (200) is embedded in the deep soil layer; the second support (21) comprises a support cross beam (210) abutted between the fender post (1) and the first support (20) and a steel upright post (211) with the top end supported at the bottom of the support cross beam (210), and the bottom end of the steel upright post (211) is embedded and inserted at the depth of a soil layer;

the reinforcement cushion assembly (4) comprises a reinforcement cushion layer (40) and a plurality of dowel bars (41) which are uniformly arranged at the bottom of the reinforcement cushion layer (40) at intervals, the reinforcement cushion layer (40) is formed by casting double-sided bidirectional reinforcement and concrete, and the reinforcement cushion layer (40) is laid on the periphery of the bottom surface of the foundation pit and is spliced with a soil layer at the bottom of the foundation pit through the dowel bars (41).

2. The foundation pit enclosure structure of claim 1, wherein: a plurality of vertical water stopping piles (11) are arranged between the fender post (1) and the side wall of the foundation pit.

3. A foundation pit enclosure structure according to claim 1 or 2, wherein: the periphery of the top of the inclined supporting pipe (200) is provided with a plurality of anchor bars, and the anchor bars are bound with the steel bar structure in the crown beam (10) into a whole.

4. A foundation pit enclosure structure according to claim 1 or 2, wherein: one end of the supporting cross beam (210) is fixedly connected with the fender post (1) through a double-splicing surrounding purlin (212), and the other end of the supporting cross beam (210) is fixedly connected with the inclined supporting pipe (200).

5. The foundation pit enclosure structure of claim 4, wherein: the double-spliced enclosing purlin (212) is of a quadrilateral structure made of I-shaped steel, channel steel or steel plates; the supporting beam (210) is of a rod-shaped structure made of round steel pipes or square steel pipes.

6. The foundation pit enclosure structure of claim 1, wherein: the connecting beam (6) is made of I-shaped steel or channel steel, and the connecting beam (6) is connected between two adjacent supporting cross beams (210).

7. A foundation pit enclosure structure according to any one of claims 1-6, wherein: the upper side of the reinforcement distribution cushion assembly (4) is provided with a built-in pit structure (3), the built-in pit structure (3) comprises a bottom plate (31), the built-in pit structure (3) is connected with the fender pile (1) through a force transmission belt (5), the inclined stay tubes (200) sequentially penetrate through the built-in pit structure (3) and the reinforcement distribution cushion assembly (4) in an inclined mode and are buried in deep soil layers, and water stop steel plates (30) are arranged at the intersecting positions of the inclined stay tubes (200) and the middle of the bottom plate (31).

8. A foundation pit enclosure structure according to claim 7, characterized in that: one end of the force transmission belt (5) is embedded and poured at one side of the in-pit building structure (3), and the other end of the force transmission belt (5) is anchored into the fender pile (1); the force transmission belt (5) comprises a bottom plate force transmission belt (50) and a middle floor plate force transmission belt (51), the main body of the bottom plate force transmission belt (50) is arranged at the upper part of the reinforced cushion layer component (4), one end of the bottom plate force transmission belt (50) is embedded and poured at one end of the bottom plate (31), and the other end of the bottom plate force transmission belt (50) is anchored into the enclosure pile (1); one side of a reinforcing steel bar of the middle floor slab force transmission belt (51) is anchored into the middle floor slab, and the other side of the reinforcing steel bar is welded with a main steel bar of the fender post (1) through a hanging steel bar; the middle floor slab force transmission belts (51) are arranged in the gap of the first support (20) and are arranged at equal intervals along the periphery of the foundation pit.

9. A construction method of a foundation pit support structure according to any one of claims 1-6, characterized by comprising the following steps:

firstly, constructing a fender pile (1), mapping and lofting according to a drawing, marking and positioning the positions of the fender pile (1) and a vertical water stop pile (11) on site, and completing construction of the fender pile (1), a crown beam (10) and the vertical water stop pile (10);

step two, constructing a first support (20), namely, after statically pressing the inclined supporting pipe (200) to a specified depth in a soil layer, firstly filling graded broken stones into the inclined supporting pipe (200), then filling pure cement into the inclined supporting pipe (200) to the top of the inclined supporting pipe (200), uniformly connecting a plurality of anchor bars around the top of the inclined supporting pipe (200) by welding, and binding and pouring the anchor bars with a steel bar structure in the crown beam (10);

thirdly, excavating first subsoil, excavating soil layers to the design position of a supporting beam (210) in a layered and partitioned manner, erecting a plurality of groups of second supports (21), fixedly connecting adjacent second supports (21) through connecting beams (6), and connecting all the second supports (21) in the foundation pit into a whole;

fourthly, excavating second soil, excavating to the bottom of the foundation pit in layers and blocks, constructing a reinforcement cushion layer assembly (4), then constructing a bottom plate (31) and a bottom plate force transmission belt (50), and arranging a water stop steel plate (30) at the intersection of the middle part of the bottom plate (31) and the inclined support pipe (200); after the strength of the bottom plate (31) and the bottom plate force transmission belt (50) meets the requirement, the connecting beam (6) and the second support (21) are dismantled, the middle floor plate and the middle floor plate force transmission belt (51) continue to be constructed, after the strength of the middle floor plate and the middle floor plate force transmission belt (51) meets the requirement, one end of the inclined supporting pipe (200) is cut off along the top surface of the bottom plate (31) in a flush manner, and the other end of the inclined supporting pipe is cut off along the side surface of the fender post (1) in a flush manner;

and fifthly, backfilling the foundation pit, wherein the building structure (3) in the construction pit is positive and negative, and backfilling the foundation pit.

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