Strengthening method for side wall of recyclable foundation pit excavated in subsection mode

Abstract

The invention provides a method for reinforcing the side wall of a recyclable foundation pit excavated in a segmented mode, and belongs to the technical field of foundation pit construction.The method comprises the following steps that a first-layer foundation pit is excavated, specifically, fixing piles are inserted into the ground behind the side wall of the foundation pit; a detachable latticed supporting structure is formed on the surface of the side wall of the foundation pit, and the latticed supporting structure is connected with the fixing piles; the next layer of foundation pit can be excavated after supporting of the side wall of each layer of foundation pit is completed, and the upper layer of latticed supporting structure and the lower layer of latticed supporting structure are detachably fixed through disc buckles; and disassembly after supporting is completed, specifically, connection between the steel cables and the fixing piles is removed through an automatic unlocking device, and then all the steel pipes and the disc buckles in the latticed supporting structure are disassembled. The mode of layered excavation and layer-by-layer reinforcement is adopted, after the foundation pit is reinforced, the steel cables, the latticed supporting structure and the fixing piles can be dismantled, recycling and reusing are achieved, and land resources and building slurry resources are saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of foundation pit construction, and more specifically, it relates to a method for reinforcing the side wall of a foundation pit with sectional excavation and recyclable type. Background Technique

[0002] The functions of the side wall support of the foundation pit are as follows: First, it ensures the stability of the side wall of the foundation pit, prevents accidents such as the collapse and landslide of the side wall soil during the excavation of the foundation pit, and guarantees the safety of construction workers and the safety of surrounding buildings, roads, pipelines and other facilities. Second, it controls the deformation of the side wall of the foundation pit, avoids adverse effects on adjacent structures due to excessive deformation of the side wall, such as cracks and inclinations in adjacent buildings, and reduces the damage to the surrounding environment. Third, it provides a safe and reliable working space for the construction inside the foundation pit, ensuring the smooth progress of construction activities such as the excavation of the foundation pit and subsequent foundation works.

[0003] At present, the common existing side wall support of the foundation pit adopts a concrete support structure, that is, a pit is dug on the ground, a reinforcement net is paved on the side wall of the foundation pit, one end of a bolt is fixed to the reinforcement net, and the other end is inserted into the pit, and concrete is poured into the pit to fix the bolt.

[0004] However, this method causes the permanent retention of concrete in the ground, occupying land resources and wasting building slurry resources. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for reinforcing the side wall of a foundation pit with sectional excavation and recyclable type, so as to solve the technical problems of occupying land resources and wasting building slurry resources existing in the prior art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: to provide a method for reinforcing the side wall of a foundation pit with sectional excavation and recyclable type, including the following steps:

[0007] First-layer foundation pit excavation: Use drilling equipment to drill inward on the side wall of the foundation pit at the fixed point, and at the same time insert a fixed pile into the ground behind the side wall of the foundation pit; a detachable grid-shaped support structure is formed on the surface of the side wall of the foundation pit through steel pipes and disk locks, and the fixed points corresponding to the top and bottom of the grid-shaped support structure are connected to the fixed pile through steel cables and automatic connection devices;

[0008] Subsequent foundation pit excavation: After the side wall support of each layer of the foundation pit is completed, the excavation of the next layer of the foundation pit can be carried out, and the grid-shaped support structures of the upper and lower layers are detachably fixed through disk locks and are connected to the fixed pile through steel cables and automatic connection devices, and the length of the fixed pile is inserted according to the depth requirement of the foundation pit;

[0009] Demolition after support: After the foundation pit no longer requires slope support, the connection between the steel cable and the fixed pile is released through the automatic unlocking device. Then, the steel cable is removed from the socket on the grid-shaped support structure. Finally, each steel pipe and socket in the grid-shaped support structure are removed.

[0010] Combined with the above technical solution, in a possible implementation, the automatic connection device includes a mounting frame, a caliper, a first reset member, and a first-level rotating head. The mounting frame is fixed inside the fixed pile, and multiple holes for inserting the steel cable and the first-level rotating head are provided on the side wall of the fixed pile. The caliper is rotatably connected to the mounting frame, and the side of the caliper facing the foundation pit has an opening for inserting the first-level rotating head. The first reset member is arranged on the caliper and is used to drive the caliper to reset after the caliper rotates due to the extrusion of the first-level rotating head. At this time, the first-level rotating head is clamped in the caliper, and the first-level rotating head is fixed to the steel cable. The automatic unlocking device is used to drive the caliper to rotate to open the opening that restricts the first-level rotating head.

[0011] Combined with the above technical solution, in a possible implementation, the automatic connection device further includes a second-level rotating head and a pushing pipe. The second-level rotating head and the pushing pipe are sleeved on the steel cable, and the second-level rotating head is used to push the first-level rotating head to move in the drill hole and insert it into the caliper.

[0012] Combined with the above technical solution, in a possible implementation, the second-level rotating head is conical, and the cross-sectional area of the end of the second-level rotating head facing the fixed pile is the smallest.

[0013] Combined with the above technical solution, in a possible implementation, the contact surface between the second-level rotating head and the first-level rotating head is an arc surface.

[0014] Combined with the above technical solution, in a possible implementation, the caliper is inclined to fit the drill hole on the side wall of the foundation pit, and the opening on the side of the caliper facing the side wall of the foundation pit is directly opposite to the first-level rotating head.

[0015] Combined with the above technical solution, in a possible implementation, the automatic unlocking device includes a pressing rod, a ring-shaped key, a second reset member, and a pulling rope. The pressing rod is fixed at the end of the caliper away from the foundation pit, and the rotation connection of the caliper is close to the middle position of itself. The second reset member is connected between the mounting frame and the ring-shaped key. When the second reset member is in the initial state, the ring-shaped key is not in contact with the pressing rod. The ring-shaped key is used to move upward to press the pressing rod so that the caliper rotates to release the first-level rotating head. One end of the pulling rope is fixed to the ring-shaped key, and the other end of the pulling rope extends to the ground.

[0016] Combined with the above technical solution, in a possible implementation manner, there are two extrusion rods which are respectively fixed on both sides of the end of the caliper, and the annular key simultaneously pushes the two extrusion rods to rotate outwards.

[0017] Combined with the above technical solution, in a possible implementation manner, there are two second reset members which are connected to both sides of the annular key, and the pulling rope is fixed at the middle position of the annular key.

[0018] Combined with the above technical solution, in a possible implementation manner, there is one pulling rope which is simultaneously fixed to the annular keys in all the automatic unlocking devices.

[0019] The beneficial effects of the sectional excavation and recyclable foundation pit sidewall reinforcement method provided by the present invention are as follows: Compared with the prior art, the present invention adopts the method of layered excavation and layer-by-layer reinforcement, and the sidewall of the foundation pit is supported layer by layer through a detachable grid-shaped support structure, and the grid-shaped support structures of the upper and lower layers are detachably fixed, so that the construction process is more orderly and flexible, and it is convenient to operate according to the actual excavation progress and requirements; the flexible steel cables and automatic connection devices are used to connect and fix each fixing point of the grid-shaped support structure and the corresponding fixing piles, and the operation is convenient and the reinforcement effect is good; after the foundation pit reinforcement is completed, the connection between each steel cable and the fixing pile can be released through the automatic unlocking device, and then the steel cables, the grid-shaped support structure and the fixing piles are removed to realize recycling. After the removal, there is no resource residue on the side of the foundation pit, saving land resources and building slurry resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a schematic structural diagram of the first-layer foundation pit reinforcement provided by the embodiment of the present invention;

[0022] Figure 2 It is a schematic structural diagram of the second-layer foundation pit reinforcement provided by the embodiment of the present invention;

[0023] Figure 3 It is a schematic structural diagram of the automatic connection device before connection provided by the embodiment of the present invention;

[0024] Figure 4 It is a schematic structural diagram of the automatic connection device after connection provided by the embodiment of the present invention.

[0025] Among them, the reference numerals in the figures are as follows:

[0026] 1. Fixed pile; 2. Grid-shaped support structure; 21. Steel pipe; 22. Screw disk; 3. Steel cable; 4. Automatic connection device; 41. Mounting frame; 42. Caliper; 43. First reset member; 44. First-level rotating head; 45. Second-level rotating head; 46. Thrust pipe; 5. Automatic unlocking device; 51. Extrusion rod; 52. Ring key; 53. Second reset member; 54. Pull rope. Detailed implementation manners

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0028] It should be further noted that the drawings and embodiments of the present invention mainly describe and illustrate the concept of the present invention. On the basis of this concept, the specific forms and settings of some connection relationships, positional relationships, power mechanisms, power supply systems, hydraulic systems and control systems may not be completely described. However, on the premise that those skilled in the art understand the concept of the present invention, those skilled in the art can implement the above specific forms and settings in a well-known manner.

[0029] When an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0030] The orientation terms "inside" and "outside" refer to the inside and outside of the contour of each component itself. The terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present invention.

[0031] For ease of description, spatial relative terms such as "above", "over", "on the upper surface", "upper", etc. can be used here to describe the spatial positional relationship between a device or feature shown in the figure and other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figure for the device. For example, if the device in the attached figure is inverted, a device described as "above" or "over" other devices or structures will then be positioned "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways, and corresponding interpretations are made for the spatial relative descriptions used here.

[0032] The terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, and "several" means one or more, unless otherwise specifically defined.

[0033] A method for reinforcing the side wall of a foundation pit with sectional excavation and recyclability provided by the present invention will now be described.

[0034] As Figures 1 to 3 shown, an embodiment of the present invention provides a method for reinforcing the side wall of a foundation pit with sectional excavation and recyclability, including the following steps:

[0035] Excavation of the first layer of the foundation pit: Use drilling equipment to drill vertically inward in the direction perpendicular to the side wall of the foundation pit at the fixed points, and at the same time insert a fixed pile 1 on the ground behind the side wall of the foundation pit; A detachable grid-shaped support structure 2 is formed on the surface of the side wall of the foundation pit through steel pipes 21 and disk locks 22. The fixed points corresponding to the top and bottom of the grid-shaped support structure 2 are connected to the fixed pile 1 through steel cables 3 and automatic connection devices 4;

[0036] Subsequent excavation of the foundation pit: After the side wall of each layer of the foundation pit is supported, the excavation of the next layer of the foundation pit can be carried out. The grid-shaped support structures 2 of the upper and lower layers are detachably fixed through disk locks 22, and are connected to the fixed pile 1 through steel cables 3 and automatic connection devices 4. The length of the fixed pile 1 is inserted according to the depth requirement of the foundation pit;

[0037] Demolition after support: After the foundation pit no longer requires slope support, the connection between the steel cable 3 and the fixed pile 1 is released through the automatic unlocking device 5. Then, the steel cable 3 is removed from the socket 22 on the grid-shaped support structure 2. Finally, each steel pipe 21 and socket 22 in the grid-shaped support structure 2 are removed.

[0038] A method for reinforcing the side wall of a foundation pit with sectional excavation and recyclability provided in this embodiment, compared with the prior art, adopts the method of layered excavation and layer-by-layer reinforcement. The side wall of the foundation pit is supported layer by layer through the detachable grid-shaped support structure 2, and the grid-shaped support structures 2 of the upper and lower layers are detachably fixed to each other, making the construction process more orderly and flexible, and facilitating operation according to the actual excavation progress and requirements. The flexible steel cable 3 and the automatic connection device 4 are used to connect and fix each fixing point of the grid-shaped support structure 2 and the corresponding fixed pile 1, with convenient operation and good reinforcement effect. After the foundation pit reinforcement is completed, the connection between each steel cable 3 and the fixed pile 1 can be released through the automatic unlocking device 5, and then the steel cable 3, the grid-shaped support structure 2 and the fixed pile 1 are removed for recycling. After removal, there is no resource residue on the side of the foundation pit, saving land resources and building slurry resources.

[0039] As Figures 3 to 4 shown, a specific implementation manner provided by the present invention on the basis of the above embodiment is as follows:

[0040] The automatic connection device 4 includes an installation frame 41, a caliper 42, a first reset member 43 and a first-level rotating head 44. The installation frame 41 is fixed inside the fixed pile 1, and a plurality of holes for inserting the steel cable 3 and the first-level rotating head 44 are provided on the side wall of the fixed pile 1. The caliper 42 is rotatably connected to the installation frame 41, and the side of the caliper 42 facing the foundation pit has an opening for inserting the first-level rotating head 44. The first reset member 43 is arranged on the caliper 42 and is used to drive the caliper 42 to reset after the caliper 42 rotates due to the extrusion of the first-level rotating head 44. At this time, the first-level rotating head 44 is clamped inside the caliper 42, and the first-level rotating head 44 is fixed to the steel cable 3. The automatic unlocking device 5 is used to drive the caliper 42 to rotate to open the opening restricting the first-level rotating head 44.

[0041] Before installing the grid-shaped support structure 2, the end of the steel cable 3 with the first-level rotating head 44 is inserted into the corresponding drill hole, and the first-level rotating head 44 is inserted into the caliper 42. The first reset member 43 drives the caliper 42 to rotate and reset after the first-level rotating head 44 is inserted into the caliper 42, realizing the automatic connection between the steel cable 3 and the fixed pile 1, and effectively resisting the acting force from the side wall of the foundation pit during the side wall support process of the foundation pit, ensuring the stability of the support structure. Moreover, the connection between the steel cable 3 and the fixed pile 1 can be released by operating the caliper 42 through the automatic unlocking device 5, realizing the recycling of the support structure and improving the construction efficiency.

[0042] AsFigures 3 to 4 As shown in the figure, a specific implementation provided by the present invention on the basis of the above-mentioned embodiments is as follows:

[0043] The automatic connection device 4 further includes a secondary rotating head 45 and a pushing pipe 46. The secondary rotating head 45 and the pushing pipe 46 are sleeved on the steel cable 3. The secondary rotating head 45 is used to push the primary rotating head 44 to move in the drill hole and insert it into the caliper 42.

[0044] The secondary rotating head 45 and the pushing pipe 46 can push the rotating shaft to move in the drill hole and insert it into the caliper 42, making the connection process between the steel cable 3 and the fixed pile 1 smoother and more efficient. Especially in a complex construction environment, it is more helpful to accurately and quickly complete the connection operation between the steel cable 3 and the fixed pile 1. And after the primary rotating head 44 is inserted into the caliper 42, the secondary rotating head 45 and the pushing pipe 46 can be directly pulled outwards for operation at the next drill hole, realizing repeated use.

[0045] As Figures 3 to 4 As shown in the figure, a specific implementation provided by the present invention on the basis of the above-mentioned embodiments is as follows:

[0046] The secondary rotating head 45 is conical, and the cross-sectional area of the end of the secondary rotating head 45 facing the fixed pile 1 is the smallest.

[0047] The shape design of the secondary rotating head 45 is beneficial to reducing resistance when pushing the primary rotating head 44. During the pushing process, the conical secondary rotating head 45 can more smoothly transmit the force to the primary rotating head 44, making the primary rotating head 44 easier to enter the caliper 42, improving the reliability and efficiency of the connection.

[0048] As Figures 3 to 4 As shown in the figure, a specific implementation provided by the present invention on the basis of the above-mentioned embodiments is as follows:

[0049] The contact surface between the secondary rotating head 45 and the primary rotating head 44 is an arc surface. It can increase the friction between the secondary rotating head 45 and the primary rotating body, and further improve the stability of the secondary rotating head 45 when pushing the primary rotating body.

[0050] As Figures 3 to 4 As shown in the figure, a specific implementation provided by the present invention on the basis of the above-mentioned embodiments is as follows:

[0051] The caliper 42 is inclined to fit the drill hole on the side wall of the foundation pit, and the opening of the caliper 42 facing the side wall of the foundation pit is directly opposite to the primary rotating head 44.

[0052] Since the side wall of the foundation pit is an inclined surface, the drilling and movement directions of the first-stage rotary head 44 are also inclined. The adaptive inclined setting of the caliper 42 helps the first-stage rotary head 44 to be accurately inserted into the caliper 42, thereby improving the accuracy and stability of the connection between the steel cable 3 and the fixed pile 1, and is conducive to better playing the role of the support structure.

[0053] like Figures 3 to 4 As shown, the present invention provides a specific implementation method based on the above implementation method as follows:

[0054] The automatic unlocking device 5 includes a squeezing rod 51, a ring key 52, a second reset member 53 and a pull rope 54. The squeezing rod 51 is fixed to the end of the caliper 42 away from the foundation pit, and the rotating connection of the caliper 42 is close to the middle position of itself; the second reset member 53 is connected between the mounting frame 41 and the ring key 52. ​​When the second reset member 53 is in the initial state, the ring key 52 and the squeezing rod 51 are in a non-contact state; the ring key 52 is used to move upward to squeeze the squeezing rod 51 so that the caliper 42 rotates to loosen the first-stage rotating head 44; one end of the pull rope 54 is fixed to the ring key 52, and the other end of the pull rope 54 extends to the ground.

[0055] When the support structure needs to be dismantled, the ring key 52 can be pulled by the pull rope 54, and the ring key 52 moves upward to squeeze the squeezing rod 51, so that the caliper 42 rotates to loosen the first-stage turntable 44, thereby releasing the connection between the steel cable 3 and the fixed pile 1, realizing automatic disassembly of the support structure, and improving the convenience and efficiency of disassembly.

[0056] like Figures 3 to 4 As shown, the present invention provides a specific implementation method based on the above implementation method as follows:

[0057] There are two squeezing rods 51 which are respectively fixed on both sides of the end of the caliper 42 , and the ring key 52 pushes the two squeezing rods 51 to rotate outwards at the same time.

[0058] The ring key 52 simultaneously pushes the two squeezing rods 51 to rotate outwards. This simultaneous force design makes the rotation of the caliper 42 more stable and balanced, and can more reliably loosen the first-stage rotating head 44, avoiding the problem of the caliper 42 being stuck or the first-stage rotating head 44 being unable to be completely loosened due to unilateral force.

[0059] like Figures 3 to 4 As shown, the present invention provides a specific implementation method based on the above implementation method as follows:

[0060] There are two second restoring members 53 connected to both sides of the ring key 52 , and the pull rope 54 is fixed at the middle position of the ring key 52 .

[0061] The annular key 52 is made more balanced during the force application and reset processes, and the pulling rope 54 can more effectively transmit force when pulling the annular key 52. At the same time, it also facilitates the operation of the annular key 52, further improving the reliability and efficiency of the automatic disassembly process.

[0062] As Figures 3 to 4 shown, a specific embodiment provided by the present invention on the basis of the above embodiment is as follows:

[0063] The pulling rope 54 has one and is simultaneously fixed to all the annular keys 52 in the automatic unlocking device 5.

[0064] Only by pulling one pulling rope 54 can all the steel cables 3 connected to the same fixed pile 1 be removed simultaneously, further improving the operation convenience.

[0065] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

[0066] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0067] Unless otherwise specifically stated, the relative arrangements of the components and steps set forth in these embodiments, the numerical expressions and values do not limit the scope of the present application. At the same time, it should be understood that for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

Claims

1. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit, characterized in that: The following steps are involved: Excavation of the first foundation pit: using a drilling device to drill holes inwards on the side wall of the foundation pit at the consolidation point, and inserting fixed piles (1) on the ground behind the side wall of the foundation pit; the surface of the side wall of the foundation pit is formed into a detachable grid-like support structure (2) through steel pipes (21) and buckles (22); the consolidation points corresponding to the top and bottom ends of the grid-like support structure (2) are connected to the fixed piles (1) through steel cables (3) and automatic connection devices (4); Subsequent foundation pit excavation: After the side wall support of each layer of foundation pit is completed, the foundation pit of the next layer can be excavated. The upper and lower layers of the grid-shaped support structure (2) are detachably fixed by means of a buckle (22), and are connected to the fixed pile (1) by means of a steel cable (3) and an automatic connection device (4). The length of the fixed pile (1) is inserted according to the depth requirement of the foundation pit; Disassembly after support is completed: When the foundation pit does not need to perform slope support, the connection between the steel cable (3) and the fixed pile (1) is released by the automatic unlocking device (5), and then the steel cable (3) is removed from the buckle (22) on the grid-like support structure (2), and finally the various steel pipes (21) and buckles (22) in the grid-like support structure (2) are removed.

2. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 1, characterized in that: The automatic connection device (4) comprises a mounting frame (41), a caliper (42), a first reset member (43) and a first-stage rotary head (44); the mounting frame (41) is fixed inside the fixed pile (1); a plurality of holes for inserting the steel cable (3) and the first-stage rotary head (44) are provided on the side wall of the fixed pile (1); the caliper (42) is rotatably connected to the mounting frame (41); the side of the caliper (42) facing the foundation pit has an opening for inserting the first-stage rotary head (44); the first reset member (43) is arranged on the caliper (42) and is used to drive the caliper (42) to reset after the caliper (42) is squeezed by the first-stage rotary head (44) and rotates completely, at which time the first-stage rotary head (44) is clamped in the caliper (42), and the first-stage rotary head (44) is fixed to the steel cable (3); the automatic unlocking device (5) is used to drive the caliper (42) to rotate to open the opening that restricts the first-stage rotary head (44).

3. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 2, characterized in that: The automatic connection device (4) further comprises a secondary rotary head (45) and a push tube (46), wherein the secondary rotary head (45) and the push tube (46) are sleeved on the steel cable (3), and the secondary rotary head (45) is used to push the primary rotary head (44) to move in the borehole and insert into the caliper (42).

4. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 3, characterized in that: The secondary rotating head (45) is in a cone shape, and the cross-sectional area of ​​the end of the secondary rotating head (45) facing the fixed pile (1) is the smallest.

5. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 3, characterized in that: The contact surface between the secondary rotor (45) and the primary rotor (44) is an arc-shaped surface.

6. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 2, characterized in that: The caliper (42) is arranged to be inclined to fit the hole drilled on the side wall of the foundation pit, and the opening of the caliper (42) facing one side of the side wall of the foundation pit is directly opposite to the primary rotating head (44).

7. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 2, characterized in that: The automatic unlocking device (5) comprises a squeezing rod (51), a ring key (52), a second reset member (53) and a pull rope (54); the squeezing rod (51) is fixed to one end of the caliper (42) away from the foundation pit, and the rotation connection of the caliper (42) is close to the middle position of the caliper itself; the second reset member (53) is connected between the mounting frame (41) and the ring key (52); when the second reset member (53) is in an initial state, the ring key (52) and the squeezing rod (51) are in a non-contact state; the ring key (52) is used to move upward to squeeze the squeezing rod (51) so that the caliper (42) rotates to loosen the primary rotating head (44); one end of the pull rope (54) is fixed to the ring key (52), and the other end of the pull rope (54) extends to the ground.

8. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 7, characterized in that: There are two squeezing rods (51) which are respectively fixed on both sides of the end of the caliper (42). The ring key (52) pushes the two squeezing rods (51) to rotate outward at the same time.

9. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 8, characterized in that: There are two second reset members (53) connected to both sides of the ring key (52), and the pull rope (54) is fixed at the middle position of the ring key (52).

10. A method for reinforcing the sidewall of a partially excavated and recyclable foundation pit as claimed in claim 7, characterized in that: The pull rope (54) has one and is simultaneously fixed to the ring key (52) in all the automatic unlocking devices (5).

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