Fabricated foundation pit supporting and waterproof integrated system and construction method thereof

Abstract

The invention discloses a fabricated foundation pit support waterproof integrated system and a construction method thereof, and belongs to the technical field of building foundation pit support. Comprising first steel sheet piles, second steel sheet piles, water stop cavity forming plates and inner supporting frames, a rectangular frame structure is defined by the multiple first steel sheet piles, the four corners of the rectangular frame structure are each provided with one second steel sheet pile, and the multiple inner supporting frames are arranged in the rectangular frame structure; when the assembly type foundation pit supporting waterproof integrated system is used, a closed structure jointly defined by the first steel sheet piles and the second steel sheet piles is arranged underground at the site selection position of a foundation pit, connecting bolts, connected with the water stop cavity forming plates, at the upper ends of the first steel sheet piles and the second steel sheet piles are higher than the ground, and then all the water stop cavity forming plates are pulled out; and a cavity formed after the water stop cavity forming plate is pulled out is filled with water stop materials to form a water stop column, and then foundation pit excavation is conducted. The construction method has the advantages of being high in construction speed, good in economical efficiency, free of slurry pollution, stable in water stopping effect and the like.

Description

Technical Field

[0001] The invention relates to an assembled foundation pit support waterproofing integrated system and a construction method thereof, and belongs to the technical field of building foundation pit enclosures. Background Art

[0002] The foundation pit is a soil pit excavated at the foundation design location according to the base elevation and foundation plane dimensions. Before excavation, the excavation plan should be determined based on geological and hydrological data and the situation of nearby buildings on site, and waterproofing and drainage work should be done. If the excavation is not deep, the side slope can be used to stabilize the soil slope, and the slope size is determined according to relevant construction regulations. For those who have deeper excavations and nearby buildings, the foundation pit wall support method and shotcrete wall protection method can be used. Large foundation pits can even use underground continuous walls and column-type bored pile interlocking methods to protect the foundation pit from collapsing on the outside soil layer. That is, foundation pit support is a support, reinforcement and protection measure for the side walls of the foundation pit and the surrounding environment to ensure the safety of underground structure construction and the surrounding environment of the foundation pit. In today's rapidly developing construction industry, foundation pit support technology has always been a key link in the construction process.

[0003] The main functions of the foundation pit support structure are retaining soil and stopping water. The foundation pit support (enclosure) methods include slope excavation, cement soil retaining wall, high-pressure jet grouting piles, channel steel sheet piles, reinforced concrete sheet piles, bored piles and underground continuous walls. The support structure can also be divided into two types according to the manufacturing process: cast-in-place and prefabricated assembly. The cast-in-place foundation pit support structure generally refers to the structure that has a certain strength and can bear the lateral water and soil pressure at the construction site, where the trench is first formed, the steel cage is placed, and then the cementitious material is poured. Commonly used ones include bored piles, underground continuous walls, etc. There are also cement soil mixing first, and then steel is inserted, such as SMW method piles. The cast-in-place support structure has the advantages of good integrity, high rigidity, good anti-leakage performance, and wide application of geological conditions. The disadvantages are that the construction site is highly polluted, large machinery and equipment are required for construction, the construction process is relatively complex, the construction period is long, and the project cost is high. Prefabricated foundation pit support structure generally refers to the support retaining wall components that have been completed and only need to be assembled and implemented at the construction site, such as steel pipe columns, steel sheet piles, etc. This type of support method has the advantages of no pollution at the construction site, simple construction process, fast construction speed, and recyclable support structure. However, its disadvantages are also obvious. It cannot block water and fine particles in the soil, and the water-stopping effect is poor. Therefore, in order to prevent leakage, the project mainly uses waterproof materials or waterproof expansion strips at the joints, or fills the gaps between the adjacent steel sheet pile locks with hemp roots, fly ash, sawdust, expansion cement and other materials for waterproofing.

[0004] With the increasing awareness of environmental protection and the continuous innovation of construction technology, people are gradually pursuing a green, environmentally friendly and easy-to-construct slope protection structure. The prefabricated and assembled support structure meets such needs, but it is waterproofed by applying waterproof materials or setting waterproof expansion strips at the joints, or inserting waterproof materials into the gaps at the locks. It is not convenient for standardized construction operations, the gaps are unstable, and the waterproof effect is greatly affected by the personal experience of the staff. Based on this, this application is filed. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is to solve the problem that the existing prefabricated and assembled foundation pit support structure has poor anti-seepage and water-stopping settings and is not convenient for quickly forming a stable water-stopping structure.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides an assembled integrated foundation pit support and waterproofing system, which is arranged in a foundation pit to support the foundation pit, and includes a first steel sheet pile, a second steel sheet pile, a water stop cavity forming plate and an inner support frame. A plurality of the first steel sheet piles form a rectangular frame structure, and a second steel sheet pile is respectively arranged at the four corners of the rectangular frame structure. All the first steel sheet piles and the second steel sheet piles are combined to form a closed structure, and a plurality of the inner support frames are arranged in the closed structure.

[0009] The waterstop cavity forming plates are respectively arranged on the left and right sides of the first steel sheet pile and the second steel sheet pile. The first steel sheet pile and the second steel sheet pile are respectively connected and fixed to the corresponding waterstop cavity forming plates at their upper ends by at least two bolts. The waterstop cavity forming plates on adjacent sides of two adjacent first steel sheet piles on each side of the rectangular frame structure overlap with each other. The waterstop cavity forming plates on both sides of the second steel sheet piles at the four corners of the rectangular frame structure overlap with the adjacent waterstop cavity forming plates on the first steel sheet piles located on both sides of the second steel sheet piles.

[0010] When using the assembled foundation pit support and waterproofing integrated system, the closed structure formed by the first steel sheet pile and the second steel sheet pile is arranged underground at the foundation pit site, and the connecting bolts of the first steel sheet pile and the second steel sheet pile connecting the water-stop cavity forming plates at the upper ends are raised above the ground. Then all the water-stop cavity forming plates are pulled out, and the cavity formed after pulling out the water-stop cavity forming plates is filled with water-stop materials to form water-stop columns. Then the foundation pit is excavated.

[0011] Furthermore, the first steel sheet pile is a C-shaped structure, the second steel sheet pile is a right-angle plate, the opening directions of two adjacent first steel sheet piles on each side of the rectangular frame structure are opposite, the wing plates on both sides of the first steel sheet pile respectively extend an extension wall outward, the water stop cavity forming plate is installed on the extension wall, and the water stop cavity forming plates are respectively installed on the supporting wall plates on both sides of the second steel sheet pile.

[0012] Furthermore, on each side of the rectangular frame structure, the ends of the extension walls on the adjacent sides of two adjacent first steel sheet piles are respectively fitted with the wing plates on the other side, and the width of the extension wall is the same as the width of the water stop cavity forming plate.

[0013] Furthermore, the water stop cavity forming plates are respectively installed on the inner sides of the supporting wall plates on both sides of the second steel sheet pile, and a baffle plate is arranged on the supporting wall plate of the second steel sheet pile inside the water stop cavity forming plate, and the baffle plate is fitted with the end of the extended wall of the first steel sheet pile, and the end of the supporting wall plate of the second steel sheet pile is fitted with the wing plate of the first steel sheet pile.

[0014] Furthermore, the water-stopping cavity formed on the first steel sheet pile and the second steel sheet pile has an upper end that is higher than the first steel sheet pile and the second steel sheet pile, respectively.

[0015] Furthermore, the lower end of the extension wall and the lower end of the supporting wall plate of the second steel sheet pile are respectively provided with excavation blocks, and the excavation blocks are triangular blocks, the upper side of which is a plane for accommodating the lower end of the water-stop cavity forming plate, and the lower end is a sharp blade.

[0016] Furthermore, first water stop strips are respectively arranged at the joint between the first steel sheet pile wing plate and the water stop cavity forming plate and on the extension wall, and a water stop groove for accommodating the first water stop strip is arranged on the water stop cavity forming plate.

[0017] Furthermore, second water stop strips corresponding to the water stop grooves on the water stop cavity forming plate are respectively provided at the joint between the supporting wall plate of the second steel sheet pile and the water stop cavity forming plate and on the baffle plate.

[0018] Furthermore, four corners of the inner support frame are respectively provided with oblique braces, and a tripod for supporting the inner support frame is installed on the first steel sheet pile.

[0019] The present invention also provides a construction method of an assembled foundation pit support and waterproofing integrated system, which comprises the following steps:

[0020] S1. Level the site where the foundation pit is located;

[0021] S2, set the positioning line and excavate the trench for retaining piles;

[0022] S3, installing the first steel sheet pile and the second steel sheet pile which have been pre-assembled with the water stop cavity forming plate;

[0023] S4, remove the two bolts on the upper end of the water-stop cavity forming plate, pull out all the water-stop cavity forming plates, and then insert bolts into at least two threaded holes on the upper ends of the extension wall and the supporting wall plate originally used to connect the water-stop cavity forming plates, so as to stabilize the two adjacent first steel sheet piles or the adjacent first steel sheet piles and the second steel sheet pile;

[0024] S5. After the cavity formed by pulling out the water-stop cavity forming plate is filled with water-stop material and reaches the designed strength;

[0025] S6. Then excavate the foundation pit and gradually install the inner support frame.

[0026] (III) Beneficial effects

[0027] The above technical solution of the present invention has the following advantages:

[0028] The present invention can quickly set up an anti-seepage water-stopping structure through the arrangement of the water-stopping cavity forming plate, and has a stable water-stopping effect. The present invention does not require a large amount of concrete pouring, the construction steps are simple, the construction is convenient, the overall construction period is short, the project progress is greatly improved, it can be recycled, and the construction cost is reduced.

[0029] The present invention can be used as a foundation pit water interception, soil retaining, anti-seepage, and load-bearing structure, and has the advantages of simple construction, recyclability, and cost saving. The present invention is an economical and reasonable enclosure structure system and construction method, which can not only reduce the floor space of the water-stopping structure and achieve a good water-stopping effect, but also greatly shorten the construction period.

[0030] In addition to the technical problems solved by the present invention, the technical features of the technical solutions constituted by the present invention, and the advantages brought about by the technical features of these technical solutions described above, other technical features of the present invention and the advantages brought about by these technical features will be further explained in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is a schematic diagram of the axonometric view of the present invention.

[0033] Figure 2 It is a schematic cross-sectional view of the present invention.

[0034] Figure 3 It is a schematic top view of the present invention.

[0035] Figure 4 It is a schematic diagram of the present invention and the foundation pit assembly.

[0036] Figure 5 Axonometric measurement of the assembly of the first steel sheet pile and the water stop cavity forming plate of the present invention Figure 1 Schematic diagram.

[0037] Figure 6 Axonometric measurement of the assembly of the first steel sheet pile and the water stop cavity forming plate of the present invention Figure 2 Schematic diagram.

[0038] Figure 7 Axonometric measurement of the assembly of the second steel sheet pile and the water stop cavity forming plate of the present invention Figure 1 Schematic diagram.

[0039] Figure 8 Axonometric measurement of the assembly of the second steel sheet pile and the water stop cavity forming plate of the present invention Figure 2 Schematic diagram.

[0040] In the figure: 1. first steel sheet pile; 2. second steel sheet pile; 3. water stop cavity forming plate; 4. inner support frame; 5. rectangular frame structure; 6. extension wall; 7. baffle; 8. excavation block; 9. first water stop strip; 10. water stop groove; 11. second water stop strip; 12. diagonal support strip; 13. tripod. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Example 1

[0044] like Figure 1-8As shown, an assembled foundation pit support and waterproofing integrated system is arranged in a foundation pit to support the foundation pit, and includes a first steel sheet pile 1, a second steel sheet pile 2, a water stop cavity forming plate 3 and an inner support frame 4. A plurality of the first steel sheet piles 1 form a rectangular frame structure 5, and a second steel sheet pile 2 is respectively arranged outside the four corners of the rectangular frame structure 5. The second steel sheet pile 2 is used to wrap two adjacent first steel sheet piles 1 at the four corners of the rectangular frame structure 5. All the first steel sheet piles 1 and the second steel sheet piles 2 are combined to form a closed structure. A plurality of the inner support frames 4 are arranged in the closed structure. The inner support frames 4 are used to improve the supporting strength of the closed structure, thereby forming a reliable and stable support for the side wall of the foundation pit.

[0045] The water-stop cavity forming plates 3 are respectively arranged on the left and right sides of the first steel sheet pile 1 and the second steel sheet pile 2, and the first steel sheet pile 1 and the second steel sheet pile 2 are respectively connected and fixed to a corresponding water-stop cavity forming plate 3 at their upper ends by at least two bolts (it can be understood that it is necessary to respectively open connecting holes at the water-stop cavity forming plate 3, at the connection between the upper end of the first steel sheet pile 1 and the water-stop cavity forming plate 3, and at the connection between the upper end of the second steel sheet pile 2 and the water-stop cavity forming plate 3, and the connecting holes are threaded holes, and can also be: 1. The connecting holes on the first steel sheet pile 1 and the second steel sheet pile 2 are threaded holes, and the connecting holes on the water-stop cavity forming plate 3 are ordinary round holes; or; 2. The connecting holes on the first steel sheet pile 1 and the second steel sheet pile 2 are ordinary round holes, and the connecting holes on the water-stop cavity forming plate 3 are threaded holes). The water-stop cavity forming plates 3 on adjacent sides of two adjacent first steel sheet piles 1 on each side of the rectangular frame structure 5 (the four side walls on the front, back, left and right sides) overlap with each other, and the water-stop cavity forming plates 3 on both sides of the second steel sheet piles 2 at the four corners of the rectangular frame structure 5 overlap with the adjacent water-stop cavity forming plates 3 on the first steel sheet piles 1 located on both sides of the second steel sheet piles 2, respectively, to form a tightly sealed water-stop support structure.

[0046] When using the assembled foundation pit support and waterproofing integrated system, the closed structure formed by the first steel sheet pile 1 and the second steel sheet pile 2 is arranged underground at the foundation pit site, and the connecting bolts connecting the water-stop cavity forming plate 3 at the upper ends of the first steel sheet pile 1 and the second steel sheet pile 2 are higher than the ground (to facilitate the subsequent removal of the water-stop cavity forming plate 3), and then all the water-stop cavity forming plates 3 are pulled out (first remove the connecting bolts at the upper ends of the water-stop cavity forming plates 3), and the cavity formed after the water-stop cavity forming plates 3 are pulled out is filled with water-stopping material to form a water-stopping column (the water-stopping material can be waterproof coating, waterproof expansion strips, hemp roots, fly ash, sawdust, expansive cement, etc.), and then the foundation pit is excavated and the inner support frame 4 is set.

[0047] Example 2

[0048] This embodiment is based on the embodiment 1, and further optimizes and refines the structure of the assembled foundation pit support waterproofing integrated system, specifically: the first steel sheet pile 1 is a C-shaped structure, the second steel sheet pile 2 is a right-angle plate, the opening directions of the two adjacent first steel sheet piles 1 on each side of the rectangular frame structure 5 are arranged oppositely, the two side wing plates of the first steel sheet pile 1 respectively extend an extension wall 6 outward, the extension wall 6 is installed with the water stop cavity forming plate 3, and the two side support wall plates of the second steel sheet pile 2 are respectively installed with the water stop cavity forming plate 3. The first steel sheet pile 1 and the second steel sheet pile 2 have simple structures, are easy to obtain materials and manufacture, and are easy to install.

[0049] In this embodiment, on each side of the rectangular frame structure 5, the ends of the extension wall 6 on the adjacent side of two adjacent first steel sheet piles 1 are respectively fitted with the wing plates of the other first steel sheet piles 1, and the width of the extension wall 6 is the same as the width of the water stop cavity forming plate 3. This facilitates the subsequent filling of water stop materials and ensures the water stop effect of the water stop column.

[0050] Example 3

[0051] This embodiment is based on the embodiment 2, and further optimizes and refines the structure of the integrated system for prefabricated foundation pit support and waterproofing, specifically: the water-stop cavity forming plates 3 are respectively installed on the inner sides of the supporting wall plates on both sides of the second steel sheet pile 2, and a baffle plate 7 is arranged on the supporting wall plate of the second steel sheet pile 2 inside the water-stop cavity forming plate 3, and the baffle plate 7 is fitted with the end of the extension wall 6 of the first steel sheet pile 1, and the end of the supporting wall plate of the second steel sheet pile 2 is fitted with the wing plate of the first steel sheet pile 1. Therefore, after the water-stop cavity forming plate 3 is pulled out, a sealed water-stop cavity structure is formed, which is convenient for the subsequent filling of water-stop materials and ensures the water-stop effect of the water-stop column.

[0052] Example 4

[0053] This embodiment is based on the embodiment 3, and further optimizes and refines the structure of the water stop cavity forming plate 3, specifically:

[0054] The upper ends of the water-stop cavity forming plates 3 arranged on the first steel sheet piles 1 and the second steel sheet piles 2 are respectively arranged higher than the first steel sheet piles 1 and the second steel sheet piles 2, so as to facilitate clamping the upper ends of the water-stop cavity forming plates 3 to pull out the water-stop cavity forming plates 3.

[0055] In this embodiment, a tunneling block 8 is respectively provided at the lower end of the extension wall 6 and the lower end of the supporting wall plate of the second steel sheet pile 2. The tunneling block 8 is a triangular block, the upper side of which is a plane for receiving the lower end of the water-stop cavity forming plate 3, and the lower end is a sharp blade. On the one hand, it can assist the process of inserting the first steel sheet pile 1 and the second steel sheet pile 2 into the ground surface, and on the other hand, it can prevent mud and rocks from being stuck between the water-stop cavity forming plate 3 and the first steel sheet pile 1 or between the water-stop cavity forming plate 3 and the second steel sheet pile 2 during the process of inserting the first steel sheet pile 1 and the second steel sheet pile 2 into the ground surface, causing the water-stop cavity forming plate 3 to bend and deform. It can protect the water-stop cavity forming plate 3 and ensure that the shape of the water-stop cavity formed by the water-stop cavity forming plate 3 after the water-stop cavity forming plate 3 is pulled out is regular and stable, and it also avoids mud and rocks from entering the water-stop cavity formed by the water-stop cavity forming plate 3 after the water-stop cavity forming plate 3 is pulled out to a certain extent.

[0056] Example 5

[0057] This embodiment is based on Embodiment 4 and further optimizes and refines the structure of the integrated system for prefabricated foundation pit support and waterproofing. Specifically, a first waterstop strip 9 is respectively provided at the joint between the wing plate of the first steel sheet pile 1 and the waterstop cavity forming plate 3 and on the extension wall 6, and a waterstop groove 10 for accommodating the first waterstop strip 9 is provided on the waterstop cavity forming plate 3.

[0058] In this embodiment, second water stop strips 11 corresponding to the water stop grooves 10 on the water stop cavity forming plate 3 are respectively provided at the joint between the supporting wall plate of the second steel sheet pile 2 and the water stop cavity forming plate 3 and on the baffle plate 7 .

[0059] By providing the first water stop strip 9, the second water stop strip 11 and the water stop groove 10, the water stop effect of the water stop column formed by filling the water stop material is greatly improved.

[0060] Example 6

[0061] This embodiment is based on the embodiment 5, and further optimizes and refines the structure of the inner support frame 4, specifically:

[0062] The four corners of the inner support frame 4 are respectively provided with oblique braces 12 to improve the deformation resistance of the support frame 4 . A tripod 13 for supporting the inner support frame 4 is installed on the first steel sheet pile 1 , and the inner support frame 4 is arranged on the tripod 13 .

[0063] Example 7

[0064] This embodiment discloses a construction method of the assembled foundation pit support and waterproofing integrated system described in the above embodiment, which comprises the following steps:

[0065] S1. Level the site where the foundation pit is located;

[0066] S2, laying out the positioning line and excavating trenches for the retaining piles (the first steel sheet pile 1 and the second steel sheet pile 2);

[0067] S3, installing the first steel sheet pile 1 and the second steel sheet pile 2 which have been pre-assembled with the water stop cavity forming plate 3 to form a closed structure surrounding the four sides of the foundation pit;

[0068] S4. Remove the two bolts on the upper end of the water-stop cavity forming plate 3, pull out all the water-stop cavity forming plates 3, and then insert bolts into at least two threaded holes (if they are ordinary round holes, bolt assemblies with nuts are inserted) on the upper ends of the supporting wall plates of the extension wall 6 of the first steel sheet pile 1 and the second steel sheet pile 2 originally used to connect the water-stop cavity forming plate 3, so as to stabilize the two adjacent first steel sheet piles 1 or the adjacent first steel sheet piles 1 and the second steel sheet piles 2, and prevent the subsequent support piles from shifting and deforming, which will cause the water-stop column to deform; (In order to improve the relative fixing effect between the two adjacent first steel sheet piles 1 or the adjacent first steel sheet piles 1 and the second steel sheet piles 2, a plurality of corresponding threaded holes can also be arranged along the longitudinal array of the supporting wall plates of the extension wall 6 of the first steel sheet pile 1 and the second steel sheet pile 2, and then the bolts are locked in during the foundation pit excavation process or after the foundation pit is excavated (at this time, the water-stop material can be set after the foundation pit excavation is completed and all bolts are locked, or the water-stop material that the bolts can pass through can be filled before the foundation pit excavation)).

[0069] S5, filling the cavity formed after the water-stop cavity forming plate 3 is pulled out with water-stop material;

[0070] S6. Then, the foundation pit is excavated and the inner support frame 4 is gradually installed.

[0071] The foundation pit support structure of the present application has the characteristics of fast construction speed, good economy, no mud pollution, stable water-stopping effect, and no fear of wall deformation.

[0072] In addition, in the description of the invention, unless otherwise specified, the terms "multiple", "multiple roots", "multiple groups" are used to mean two or more than two, and "several", "several roots", "several groups" are used to mean one or more than one. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0073] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. An assembled foundation pit support and waterproof integrated system, arranged in a foundation pit to support the foundation pit, characterized in that: It includes a first steel sheet pile, a second steel sheet pile, a water stop cavity forming plate and an inner support frame, wherein a plurality of the first steel sheet piles form a rectangular frame structure, a second steel sheet pile is respectively arranged at the four corners of the rectangular frame structure, and all the first steel sheet piles and the second steel sheet piles are combined to form a closed structure, and a plurality of the inner support frames are arranged in the closed structure; The water-stop cavity forming plates are respectively arranged on the left and right sides of the first steel sheet pile and the second steel sheet pile, and the first steel sheet pile and the second steel sheet pile are respectively connected and fixed to the corresponding water-stop cavity forming plates at their upper ends by at least two bolts, and the water-stop cavity forming plates on the adjacent sides of two adjacent first steel sheet piles on each side of the rectangular frame structure overlap with each other, and the water-stop cavity forming plates on the two sides of the second steel sheet piles at the four corners of the rectangular frame structure overlap with the adjacent water-stop cavity forming plates on the first steel sheet piles located on both sides of the second steel sheet piles respectively; When using the assembled foundation pit support and waterproofing integrated system, the closed structure formed by the first steel sheet pile and the second steel sheet pile is arranged underground at the foundation pit site, and the connecting bolts of the first steel sheet pile and the second steel sheet pile connecting the water-stop cavity forming plates at the upper ends are raised above the ground. Then all the water-stop cavity forming plates are pulled out, and the cavity formed after pulling out the water-stop cavity forming plates is filled with water-stop materials to form water-stop columns. Then the foundation pit is excavated.

2. The assembled foundation pit support and waterproofing integrated system according to claim 1 is characterized in that: The first steel sheet pile is a C-shaped structure, the second steel sheet pile is a right-angle plate, the opening directions of two adjacent first steel sheet piles on each side of the rectangular frame structure are opposite, the wing plates on both sides of the first steel sheet pile respectively extend an extension wall outward, the water stop cavity forming plate is installed on the extension wall, and the water stop cavity forming plates are respectively installed on the supporting wall plates on both sides of the second steel sheet pile.

3. The assembled foundation pit support and waterproofing integrated system according to claim 2 is characterized in that: On each side of the rectangular frame structure, the ends of the extension walls on the adjacent sides of two adjacent first steel sheet piles are respectively fitted with the wing plates on the other side, and the width of the extension wall is the same as the width of the water stop cavity forming plate.

4. The assembled foundation pit support and waterproofing integrated system according to claim 3 is characterized in that: The water stop cavity forming plates are respectively installed on the inner sides of the supporting wall plates on both sides of the second steel sheet pile, and a baffle plate is arranged on the supporting wall plate of the second steel sheet pile inside the water stop cavity forming plate, and the baffle plate is fitted with the end of the extended wall of the first steel sheet pile, and the end of the supporting wall plate of the second steel sheet pile is fitted with the wing plate of the first steel sheet pile.

5. The assembled foundation pit support and waterproofing integrated system according to claim 4 is characterized in that: The water-stopping cavity formed on the first steel sheet pile and the second steel sheet pile has an upper end that is higher than the first steel sheet pile and the second steel sheet pile, respectively.

6. The assembled foundation pit support and waterproofing integrated system according to claim 5 is characterized in that: The lower end of the extension wall and the lower end of the supporting wall plate of the second steel sheet pile are respectively provided with excavation blocks, which are triangular blocks, the upper side of which is a plane for receiving the lower end of the water-stop cavity forming plate, and the lower end is a sharp blade.

7. The assembled foundation pit support and waterproofing integrated system according to claim 6 is characterized in that: The first steel sheet pile wing plate is provided with a first water stop strip at the joint between the first steel sheet pile wing plate and the water stop cavity forming plate and on the extension wall, and the water stop groove for accommodating the first water stop strip is provided on the water stop cavity forming plate.

8. The assembled foundation pit support and waterproofing integrated system according to claim 7 is characterized in that: Second water stop strips corresponding to the water stop grooves on the water stop cavity forming plate are respectively arranged at the joint between the supporting wall plate of the second steel sheet pile and the water stop cavity forming plate and on the baffle plate.

9. The assembled foundation pit support and waterproofing integrated system according to claim 8 is characterized in that: The four corners of the inner support frame are respectively provided with oblique braces, and a tripod for supporting the inner support frame is installed on the first steel sheet pile.

10. A construction method for an assembled foundation pit support and waterproofing integrated system, characterized in that: The following steps are involved: S1. Level the site where the foundation pit is located; S2, set the positioning line and excavate the trench for retaining piles; S3, installing the first steel sheet pile and the second steel sheet pile which have been pre-assembled with the water stop cavity forming plate; S4, remove the two bolts on the upper end of the water-stop cavity forming plate, pull out all the water-stop cavity forming plates, and then insert bolts into at least two threaded holes on the upper ends of the extension wall and the supporting wall plate originally used to connect the water-stop cavity forming plates, so as to stabilize the two adjacent first steel sheet piles or the adjacent first steel sheet piles and the second steel sheet pile; S5, filling the cavity formed after the water-stop cavity forming plate is pulled out with water-stop material; S6. Then excavate the foundation pit and gradually install the inner support frame.

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