A kind of assembled foundation pit retaining structure and construction method

Abstract

The application discloses a kind of assembled foundation pit retaining structure and construction method, it is related to foundation pit design and construction field, including prefabricated diaphragm wall, the prefabricated diaphragm wall top is connected first prefabricated support by cast-in-place crown beam, prefabricated diaphragm wall inside is connected second prefabricated support by prefabricated waist beam;The prefabricated diaphragm wall includes at least two sections of different height diaphragm wall section, adjacent prefabricated diaphragm wall is used staggered joint;Diaphragm wall section is used recess and convex tenon type splicing mode between, and a plurality of thin-walled cavities are equipped in the diaphragm wall section.The application uses high-performance steel fiber reinforced concrete to replace traditional reinforced concrete, divides underground continuous wall and internal support system into multiple prefabricated modules, wherein support system can be recycled, realize prefabricated assembly component high crack resistance, high environmental protection, low self-weight characteristics;Retaining structure prefabricated assembly module is connected between using fast mode, improve construction efficiency.

Description

Technical Field

[0001] This invention relates to the field of foundation pit design and construction, and in particular to a prefabricated foundation pit retaining structure and construction method. Background Technology

[0002] In urban construction and underground engineering, foundation pit retaining structures are a crucial engineering technology. "Retaining" typically refers to the walls and piles used for soil retention and water prevention, while "protecting" generally refers to the internal support system of the foundation pit. Traditional foundation pit retaining structures usually employ concrete pouring or steel welding, which presents two major problems: First, they require significant labor and materials, have long on-site construction periods, and the used support system is often simply cut off and discarded, resulting in substantial waste of project funds and labor costs, and being detrimental to environmental protection. Second, on-site pouring construction involves varying skill levels among construction teams, leading to numerous problems in the finished product, such as water leakage at critical joints and substandard wall flatness, creating safety hazards and poor maintainability. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide a prefabricated foundation pit retaining structure and construction method. This method utilizes high-performance steel fiber reinforced concrete instead of traditional reinforced concrete, dividing the underground continuous wall and internal support system into multiple prefabricated modules that can be assembled. The support system is reusable, achieving high crack resistance, environmental friendliness, and low self-weight in the prefabricated components. A rapid connection method is used between the prefabricated modules of the retaining structure to improve construction efficiency.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0005] In a first aspect, embodiments of the present invention provide a prefabricated foundation pit retaining structure, including a prefabricated diaphragm wall. The top of the prefabricated diaphragm wall is connected to the first prefabricated support via a cast-in-place cap beam, and the inner side of the prefabricated diaphragm wall is connected to the second prefabricated support via a prefabricated waist beam. The prefabricated diaphragm wall includes at least two diaphragm wall sections of different heights, and adjacent prefabricated diaphragm walls are spliced ​​with staggered joints. The diaphragm wall sections are spliced ​​using a tenon-and-mortise joint method, and the diaphragm wall sections are provided with several thin-walled cavities.

[0006] As a further implementation method, the prefabricated diaphragm wall is divided into a first diaphragm wall section and a second diaphragm wall section, with 2 / 3 of the prefabricated diaphragm wall as the dividing node.

[0007] As a further implementation, the diaphragm wall sections are fitted with tenons and mortises, and water-swellable sealant is provided on both sides of the tenons; grouting holes are reserved inside the diaphragm wall sections;

[0008] A movable steel plate is inserted into the tenon position.

[0009] As a further implementation, the precast diaphragm wall is provided with diaphragm wall anchor bars, which are cast simultaneously with the cast-in-place cap beam;

[0010] The cast-in-place cap beam has a pre-reserved channel for the cap beam anchor bars, and a cap beam backing steel plate is installed on its back; the cap beam anchor bars pass through the cap beam backing steel plate and are fitted with nuts.

[0011] As a further implementation, the first precast support has a built-in first support steel bar, and the first support steel bar is connected to the cap beam anchor bar through a first support steel bar connector.

[0012] As a further implementation, a groove for anchor bars is reserved in the precast waist beam, the anchor bars extend into the reserved anchor bar groove and connect with the ground diaphragm wall steel bar connector, and the anchor bars are fastened with nuts at the ends of the waist beam.

[0013] As a further implementation, the second precast support is connected to the precast waist beam by a movable positioning steel bar, and multiple jacks for pre-tightening are installed between the second precast support and the precast waist beam.

[0014] As a further implementation, the precast diaphragm wall, cast-in-place cap beam, first precast support, precast wainscoting, and second precast support are all made of steel fiber reinforced concrete, and strain gauges are pre-embedded inside each of them.

[0015] Secondly, embodiments of the present invention also provide a construction method for a prefabricated foundation pit retaining structure, comprising:

[0016] Precast diaphragm wall construction: After the trenching machine forms the trench, the diaphragm wall sections are lowered in sections. The diaphragm wall sections are pre-embedded with water-swellable sealant and are spliced ​​by mortise and tenon joints.

[0017] Construction of cast-in-place capping beam: The top of the precast diaphragm wall is reserved with diaphragm wall anchor bars, which are poured at the same time as the cast-in-place capping beam; the capping beam anchor bar groove is reserved in the cast-in-place capping beam, and the capping beam back cover steel plate is set on the back; after the cast-in-place capping beam reaches the design strength, the first precast support is installed.

[0018] Assembling the precast wainscoting and the second precast support: The precast wainscoting has a reserved wainscoting anchor bar channel. The wainscoting anchor bar is inserted into the reserved anchor bar channel and connected to the ground diaphragm wall rebar connector. The wainscoting anchor bar is tightened with nuts at the end of the wainscoting. One end of the movable positioning steel bar is inserted into the reserved channel of the precast wainscoting, and the other end is inserted into the reserved channel of the second precast support. It is then tightened by jacks.

[0019] As a further implementation method, when there is a gap at the connection between the first precast support and the cast-in-place cap beam, micro-expansion concrete is used to fill the gap.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) The present invention divides the underground diaphragm wall and internal support system into multiple prefabricated modules that can be assembled. The support system can be repeatedly recycled, achieving the characteristics of high crack resistance, high environmental protection and low self-weight of the prefabricated assembled components. The prefabricated diaphragm wall is made up of multiple diaphragm wall sections using a tongue and groove splicing method. Adjacent prefabricated diaphragm walls are staggered, realizing rapid construction of the diaphragm wall and stable connection.

[0022] (2) The protruding tenon of the prefabricated diaphragm wall of the present invention can be accurately embedded in the concave tenon, and a movable steel plate is inserted in the reserved groove to ensure the reliability of the connection; the groove design of the protruding tenon extends the seepage path, and water-swellable sealing glue is set on both sides of the joint, while a steel plate is also set in the middle to construct three waterproof layers, ensuring the excellent waterproof performance of the joint; the prefabricated diaphragm wall is provided with a thin-walled cavity, which helps to better bear the water and soil pressure, and effectively reduces its own weight, making the force transmission path more reasonable and effectively realizing the lightweight of the assembled components.

[0023] (3) The present invention uses high-performance steel fiber concrete to replace traditional reinforced concrete, which improves the crack resistance of the component and reduces the density, thereby effectively reducing the self-weight; strain gauges are pre-embedded in the component, which can monitor the state and performance of the structure in real time, which helps to improve the quality, maintainability and sustainability of the foundation pit retaining structure. Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a cross-sectional view of the assembled foundation pit retaining structure according to one or more embodiments of the present invention;

[0026] Figure 2 This is a schematic diagram of a prefabricated diaphragm wall according to one or more embodiments of the present invention;

[0027] Figure 3 This is an elevation view of a prefabricated diaphragm wall according to one or more embodiments of the present invention;

[0028] Figure 4 This is a cross-sectional view of a prefabricated diaphragm wall according to one or more embodiments of the present invention;

[0029] Figure 5 This is a cross-sectional view of the support system according to one or more embodiments of the present invention;

[0030] Figure 6 This is a plan view of the first prefabricated support according to one or more embodiments of the present invention;

[0031] Figure 7This is a plan view of the second prefabricated support according to one or more embodiments of the present invention;

[0032] Figure 8 This is a schematic diagram of the cast-in-place cap beam backing steel plate according to one or more embodiments of the present invention;

[0033] Figure 9 This is an elevation view of the cast-in-place cap beam according to one or more embodiments of the present invention;

[0034] Figure 10 This is a schematic diagram of the positioning steel plate and jack according to one or more embodiments of the present invention;

[0035] Figure 11 This is a schematic diagram of the prefabricated wainscoting elevation according to one or more embodiments of the present invention.

[0036] Among them, 1. Precast diaphragm wall, 1-1. Diaphragm wall anchor bar, 1-2. Diaphragm wall rebar connector, 1-3. Diaphragm wall embedded steel plate, 1-4. Thin-walled cavity, 1-5. Water-swellable sealant, 1-6. Grouting hole, 1-7. Tenon, 1-8. Movable steel plate, 1-9. First diaphragm wall section, 1-10. Second diaphragm wall section, 2. Cast-in-place capping beam, 2-1. Capping beam backing steel plate, 2- 2. Crown beam anchor bar, 2-3. Nut, 3. Precast waist beam, 3-1. Waist beam anchor bar, 3-2. Waist beam embedded steel plate, 3-3. Nut, 4. First precast support, 4-1. First support embedded steel plate, 4-2. First support reinforcement bar, 4-3. First support reinforcement bar connector, 4-4. Micro-expansion concrete, 5. Second precast support, 5-1. Movable positioning steel bar, 5-2. Jack. Detailed Implementation

[0037] Example 1:

[0038] In a typical embodiment of the present invention, such as Figures 1-11 As shown, a modular foundation pit retaining structure is presented.

[0039] Traditional foundation pit retaining structures suffer from problems such as long construction cycles, significant waste, and poor maintainability. To address these issues, this embodiment provides a prefabricated foundation pit retaining structure. By using high-performance steel fiber reinforced concrete instead of traditional reinforced concrete, the underground continuous wall and internal support system are divided into multiple prefabricated modules that can be assembled. The support system is reusable, achieving high crack resistance, environmental friendliness, and low self-weight in the prefabricated components. Strain gauges are integrated within the prefabricated structure for real-time monitoring of the retaining structure's stability and condition. A quick-connect structure is used between the prefabricated modules, enabling rapid and convenient installation and disassembly, reducing on-site construction time and improving efficiency.

[0040] The above-mentioned prefabricated foundation pit retaining structure will now be described in detail with reference to the accompanying drawings.

[0041] like Figure 1 As shown, the prefabricated foundation pit retaining structure of this embodiment includes a prefabricated diaphragm wall 1, a cast-in-place cap beam 2, a prefabricated waist beam 3, a first prefabricated support 4, and a second prefabricated support 5. A cast-in-place cap beam 2 is set on the top of the prefabricated diaphragm wall 1, and the cast-in-place cap beams 2 between the prefabricated diaphragm walls 1 that are set opposite each other are connected by the first prefabricated support 4. A prefabricated waist beam 3 is set on the inner side of the prefabricated diaphragm wall 1, and the prefabricated waist beams 3 are connected by the second prefabricated support 5.

[0042] like Figures 2-4 As shown, since the maximum bending moment occurs between 1 / 3 and 2 / 3 of the diaphragm wall height, setting up sections outside this range can reduce the risk of hoisting and does not affect the operation of the diaphragm wall. Therefore, in this embodiment, each prefabricated diaphragm wall 1 is divided into two sections, with the dividing node at 2 / 3 of the wall height, that is, one diaphragm wall section is twice the height of the other diaphragm wall section.

[0043] In this embodiment, the prefabricated diaphragm wall 1 is divided into a first diaphragm wall section 1-9 and a second diaphragm wall section 1-10 along the wall height direction. The height of the second diaphragm wall section 1-10 is twice the height of the first diaphragm wall section 1-9.

[0044] Adjacent precast diaphragm walls 1 are spliced ​​with staggered joints, that is, the first diaphragm wall section 1-9 of one precast diaphragm wall 1 corresponds to the second diaphragm wall section 1-10 of the adjacent precast diaphragm wall 1; at the same time, the diaphragm wall sections are spliced ​​with mortise and tenon joints to improve the overall stability of the diaphragm wall.

[0045] Specifically, such as Figure 3 and Figure 4 As shown, each diaphragm wall section is equipped with a thin-walled cavity 1-4, which makes the cross-section of each diaphragm wall form a structure similar to an I-shaped box girder. This not only helps to better bear the water and soil pressure, but also effectively reduces the self-weight and lowers the total cost. This design also makes the force transmission path more reasonable and effectively realizes the lightweighting of assembled components.

[0046] The number and size of the thin-walled cavities 1-4 are set according to actual requirements. In this embodiment, each diaphragm wall section is provided with one thin-walled cavity 1-4 along the height direction and two thin-walled cavities 1-4 along the length direction to form a thin-walled double-hole closed cavity.

[0047] like Figure 3 and Figure 4 As shown, adjacent wall sections are joined by a tongue and groove joint. The tenon 1-7 can be precisely embedded in the tenon to achieve a quick connection. To further ensure the reliability of the connection, a groove is reserved at the joint between the tenon 1-7 and the tenon, and a movable steel plate 1-8 is inserted into the reserved groove.

[0048] Water-swellable sealant 1-5 is applied to the joint of the diaphragm wall sections on both sides of the tenon 1-7, and the sealant 1-5 is installed along the entire length. Grouting holes 1-6 are also pre-drilled inside the diaphragm wall sections. These holes are located on one side of the tenon 1-7 of each diaphragm wall section and extend from top to bottom through the section. Grout is injected through these holes to address potential leaks at the joint. The grooved design of the tenon 1-7 extends the seepage path, and the application of water-swellable sealant 1-5 on both sides of the joint, along with a movable steel plate 1-8, creates three layers of waterproofing, ensuring excellent waterproofing performance of the joint.

[0049] like Figure 5 As shown, the precast diaphragm wall 1 is provided with diaphragm wall anchor bars 1-1, and the diaphragm wall anchor bars 1-1 extend a certain length from the top of the precast diaphragm wall 1 so as to be cast at the same time as the cast-in-place crown beam 2; the precast diaphragm wall 1 is also provided with diaphragm wall embedded steel plates 1-3, which are used to connect the precast waist beam 3.

[0050] like Figure 5 and Figure 9 As shown, a channel for the anchor bar 2-2 of the cap beam is reserved in the cast-in-place cap beam 2, and a cap beam backing steel plate 2-1 is set on the back. The anchor bar 2-2 passes through the cap beam backing steel plate 2-1 to install the nut 2-3, and the cap beam backing steel plate 2-1 bears the local pressure of the nut 2-3.

[0051] The cast-in-place cap beam 2, having reached its design strength, is connected to the first precast support 4, such as... Figure 5 , Figure 6 and Figure 8 As shown, the first precast support 4 and the cast-in-place capping beam 2 are connected by a first support embedded steel plate 4-1. The first precast support 4 contains a first support reinforcing bar 4-2. The first support reinforcing bar 4-2 and the capping beam anchor bar 2-2 are connected by a first support reinforcing bar connector 4-3. If there is a gap at the connection between the first precast support 4 and the cast-in-place capping beam 2, it can be filled with micro-expansion concrete 4-4 of a grade higher than that of the capping beam to ensure that the two are tightly pressed together.

[0052] like Figure 5 and Figure 7 As shown, the precast wainscoting 3 is installed between the precast diaphragm wall 1 and the second precast support 5. A channel for the wainscoting anchor bar 3-1 is reserved within the precast wainscoting 3. The wainscoting anchor bar 3-1 extends into the reserved anchor bar channel and connects to the diaphragm wall reinforcement connector 1-2. The wainscoting anchor bar 3-1 is secured at the end of the wainscoting with a nut 3-3. Figure 10 and Figure 11 As shown, the second prefabricated support 5 is connected to the prefabricated waist beam 3 through a movable positioning steel rod 5-1, and multiple jacks 5-2 are installed between the second prefabricated support 5 and the prefabricated waist beam 3. The jacks 5-2 are used for pre-tightening to achieve the servo control of the second prefabricated support 5.

[0053] It should be noted that the anchor bar 1-1, the rebar connector 1-2, the embedded steel plate 1-3, the capping beam anchor bar 2-2, and the first support embedded steel plate 4-1 in this embodiment are named for ease of distinction and do not impose any restrictions on the structure of the anchor bar, the embedded steel plate, etc.

[0054] In this embodiment, the first precast support 4 and the second precast support 5 are both made of concrete, and the precast wainscoting 3 is a concrete wainscoting.

[0055] In addition, each component in this embodiment is pre-embedded with strain gauges, which can monitor the state and performance of the structure in real time, helping to improve the quality, maintainability and sustainability of the foundation pit retaining structure.

[0056] In this embodiment, steel fiber reinforced concrete is used as the prefabricated material for all assembled components. The addition of steel fibers significantly improves the crack resistance of the prefabricated components while reducing their density, thereby effectively reducing their self-weight. In addition, the first prefabricated support 4, the prefabricated lintel 3, and the second prefabricated support 5 are all reusable, which helps to improve the effective use of resources.

[0057] The prefabricated foundation pit retaining structure in this embodiment eliminates the time required for concrete curing during traditional concrete pouring, enabling faster foundation pit retaining and thus shortening the project cycle. Furthermore, the integration of rapid assembly methods and intelligent sensors into the retaining structure ensures the stability, maintainability, safety, and intelligence of the entire retaining structure system.

[0058] Example 2:

[0059] This embodiment provides a construction method for a prefabricated foundation pit retaining structure, which mainly includes: factory prefabrication of components (prefabricated diaphragm wall 1, first prefabricated support 4, second prefabricated support 5, prefabricated wainscoting 3), construction of the diaphragm wall, earthwork excavation, construction of cast-in-place capping beam 2 and first prefabricated support 4, earthwork excavation, and the prefabricated wainscoting 3 and second prefabricated support 5 in the following order: excavation to the bottom of the pit, structural construction, removal of supports and wainscoting, and backfilling.

[0060] Specifically, it includes the following steps:

[0061] (1) Construction of precast diaphragm wall 1: including trenching with a trenching machine, lowering the pilot section in sections (first diaphragm wall section 1-9 or second diaphragm wall section 1-10), pre-embedding water-swellable sealant 1-5 in the diaphragm wall section and ensuring that it is positioned at the design elevation, and reserving grouting holes 1-6 between the upper and lower sections to deal with potential water leakage at the joint.

[0062] Then, the construction of the subsequent sections is carried out. Accurate positioning between the preceding and following sections is required. First, overlap by 2 / 3 of the length, and then insert longitudinally and laterally to ensure accurate positioning. Water-swellable sealant 1-5 and pre-reserved grouting holes 1-6 play a key role in dealing with water leakage problems at the joints to cope with sudden water seepage.

[0063] (2) Excavate the earthwork until the bottom of the cap beam is reached, and then start the construction of the cast-in-place cap beam 2 and the installation of the first precast support 4.

[0064] Construction of cast-in-place capping beam 2: The top of the precast diaphragm wall 1 is reserved with diaphragm wall anchor bar 1-1, which is poured at the same time as the cast-in-place capping beam 2. The cast-in-place capping beam 2 is reserved with capping beam anchor bar 2-2 channel, and the capping beam back cover steel plate 2-1 is set on the back to bear the local pressure of nut 2-3.

[0065] Once the cast-in-place capping beam 2 reaches its design strength, the first precast support 4 is installed. The capping beam anchor bars 2-2 are connected to the first support rebar connector 4-3. Then, align the connector with the pre-reserved anchor bar groove on the capping beam, insert it into the groove, and tighten it with nuts 2-3 on the back of the capping beam. If there are gaps at the connection between the first precast support 4 and the cast-in-place capping beam 2, they can be filled with micro-expansion concrete 4-4 of a higher grade than the capping beam to ensure they are tightly pressed together.

[0066] (3) The earthwork is excavated in sequence, the precast waist beam 3 is installed with the precast continuous wall 1, and the precast waist beam 3 is installed with the second precast support 5.

[0067] Assemble the precast wainscoting 3 and the second precast support 5: install the precast wainscoting 3 and the precast diaphragm wall 1, and install the precast wainscoting 3 and the second precast support 5.

[0068] A pre-reserved groove for anchor bars 3-1 is provided within the precast wainscoting 3. The precast wainscoting 3 is lowered to the design elevation, and then the anchor bars 3-1 are inserted into the pre-reserved groove and connected to the diaphragm wall rebar connector 1-2. The anchor bars 3-1 are then tightened at the end of the wainscoting with nuts 3-3. Next, the movable positioning steel rod 5-1 is installed. One end of the movable positioning steel rod 5-1 is inserted into the pre-reserved groove of the precast wainscoting 3, and the other end is inserted into the pre-reserved groove of the second precast support 5. It is then tightened using jacks 5-2 to achieve servo control of the second precast support 5.

[0069] The prefabricated construction method in this embodiment divides the foundation pit retaining structure into prefabricated modules, which can better control the construction quality, reduce human error, and ensure the consistency and stability of the structure.

[0070] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A prefabricated foundation pit retaining structure, characterized in that, It includes a precast diaphragm wall, the top of which is connected to the first precast support by a cast-in-place cap beam, and the inner side of which is connected to the second precast support by a precast waist beam; The precast diaphragm wall includes at least two diaphragm wall sections of different heights, and adjacent precast diaphragm walls are spliced ​​with staggered joints; the precast diaphragm wall is divided into a first diaphragm wall section and a second diaphragm wall section with 2 / 3 of the precast diaphragm wall as the dividing node; the diaphragm wall sections are spliced ​​with a tongue and groove tenon joint, and the diaphragm wall section is provided with several thin-walled cavities. The diaphragm wall sections are connected by a tenon and a mortise, and a movable steel plate is inserted into the tenon. The precast diaphragm wall is equipped with diaphragm wall anchor bars, which are cast simultaneously with the cast-in-place capping beam; the cast-in-place capping beam has a reserved channel for the capping beam anchor bars, and a capping beam backing steel plate is installed on its back; the capping beam anchor bars pass through the capping beam backing steel plate and are fitted with nuts; the first precast support has a built-in first support reinforcement bar, and the first support reinforcement bar is connected to the capping beam anchor bars through a first support reinforcement bar connector.

2. The prefabricated foundation pit retaining structure according to claim 1, characterized in that, The tenon is provided with water-swellable sealant on both sides; the diaphragm wall section has a pre-reserved grouting hole.

3. The prefabricated foundation pit retaining structure according to claim 1, characterized in that, The precast wainscoting has a reserved channel for the wainscoting anchor bars. The wainscoting anchor bars extend into the reserved anchor bar channel and connect with the ground diaphragm wall steel bar connector. The wainscoting anchor bars are fastened with nuts at the ends of the wainscoting.

4. The prefabricated foundation pit retaining structure according to claim 3, characterized in that, The second precast support is connected to the precast waist beam by a movable positioning steel bar, and multiple jacks for pre-tightening are installed between the second precast support and the precast waist beam.

5. The prefabricated foundation pit retaining structure according to claim 1, characterized in that, The precast diaphragm wall, cast-in-place cap beam, first precast support, precast wainscoting, and second precast support are all made of steel fiber reinforced concrete and have strain gauges embedded inside.

6. A construction method for a prefabricated foundation pit retaining structure according to any one of claims 1-5, characterized in that, include: Precast diaphragm wall construction: After the trenching machine forms the trench, the diaphragm wall sections are lowered in sections. The diaphragm wall sections are pre-embedded with water-swellable sealant and are spliced ​​by mortise and tenon joints. Construction of cast-in-place capping beam: The top of the precast diaphragm wall is reserved with diaphragm wall anchor bars, which are poured at the same time as the cast-in-place capping beam; the capping beam anchor bar groove is reserved in the cast-in-place capping beam, and the capping beam back cover steel plate is set on the back; after the cast-in-place capping beam reaches the design strength, the first precast support is installed. Assembling the precast wainscoting and the second precast support: The precast wainscoting has a reserved wainscoting anchor bar channel. The wainscoting anchor bar is inserted into the reserved anchor bar channel and connected to the ground diaphragm wall rebar connector. The wainscoting anchor bar is tightened with nuts at the end of the wainscoting. One end of the movable positioning steel bar is inserted into the reserved channel of the precast wainscoting, and the other end is inserted into the reserved channel of the second precast support. It is then tightened by jacks.

7. The construction method of a prefabricated foundation pit retaining structure according to claim 6, characterized in that, When there is a gap at the connection between the first precast support and the cast-in-place cap beam, micro-expansion concrete is used to fill the gap.

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