Prestressing system and prestressing method for the retaining wall within the excavation pit

Abstract

This invention discloses a prestressing system and method for applying prestress to retaining walls within a foundation pit. The prestressing system includes a top support device (1); the top support device includes a top support base (11) and a top support telescopic arm (12); the top support base is mounted on a horizontal support (41) near the pit bottom, and the top support output end of the top support telescopic arm can extend obliquely downwards to apply top support prestress to the retaining wall near the pit bottom. The prestressing method includes: installing the prestressing system based on the horizontal support near the pit bottom, and completing the installation of the prestressing system before subsequent excavation work on the next lower level; applying top support prestress to the retaining wall near the pit bottom using the prestressing system. The retaining wall near the pit bottom can receive applied top support prestress immediately, allowing for timely correction of displacement and deformation at the bottom of the retaining wall, thereby improving the overall engineering quality of the foundation pit project.

Description

Technical Field

[0001] This invention relates to the field of foundation pit engineering technology, and more particularly to a prestressing system and method for applying prestress to the retaining wall within a foundation pit. Background Technology

[0002] Excavation of foundation pits can cause settlement and displacement of the surrounding strata, thus affecting the safety of nearby subway tunnels and buildings. The main reason for this is that excavation leads to displacement and deformation of the surrounding soil. Therefore, during the construction of foundation pit projects, it is necessary to simultaneously construct a retaining support system to support the retaining structures around the foundation pit and ensure the safety of the surrounding environment.

[0003] In addition, a servo system will be installed on the retaining support system to actively apply top support prestress to the retaining structure in order to resist the displacement and deformation of the soil around the foundation pit.

[0004] The current problem is:

[0005] The existing servo system mainly achieves "applying lateral top support prestress to the retaining structure". However, the process of excavating the foundation pit and constructing the lower-level foundation pit structure requires a long construction period. Before the lower-level foundation pit structure is completed, it is impossible to apply top support prestress to the retaining structure near the bottom of the pit. As a result, the retaining structure near the bottom of the pit may experience displacement and deformation before the lower-level foundation pit structure is completed, which is detrimental to the construction quality of the entire foundation pit project. Summary of the Invention

[0006] The purpose of this invention is to provide a prestressing system and a prestressing method for applying prestress to the retaining wall within a foundation pit. This prestressing system and method can apply top support prestress to the retaining wall near the bottom of the pit based on horizontal supports near the pit bottom.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0008] A prestressing system for applying prestress to the retaining structure within a foundation pit, the prestressing system comprising a top support device;

[0009] The top support device includes a top support base and a top support telescopic arm;

[0010] One end of the top support telescopic arm serves as the assembly end, and the other end of the top support telescopic arm serves as the top support output end;

[0011] The assembly end of the top support telescopic arm is assembled and connected to the top support base.

[0012] The top support telescopic arm is equipped with an angle adjustment mechanism, which is used to drive the top support telescopic arm to swing up and down.

[0013] The top support base of the top support device is mounted on the horizontal support near the bottom of the pit. The top support output end of the top support telescopic arm can extend toward the bottom of the pit and apply top support prestress to the bottom of the pit.

[0014] Furthermore, the prestressing system also includes an elevation adjustment device;

[0015] The elevation adjustment device includes a support base and an elevation adjustment winch.

[0016] The support seat is placed against the bottom of the enclosure near the pit, and the height adjustment winch is used to drive the support seat to move up and down against the bottom of the enclosure near the pit.

[0017] The top support output end of the top support telescopic arm applies top support prestress to the area near the bottom of the pit through the load-bearing seat.

[0018] Furthermore, the height-adjusting winch is installed on a horizontal support near the bottom of the pit.

[0019] Furthermore, the bearing seat has a bearing surface, which is inclined upward and toward the top support base of the top support device.

[0020] Furthermore, a top support end is provided on the top support output end of the top support telescopic arm, and the top support end is assembled on the top support output end of the top support telescopic arm through a shaft pin mechanism.

[0021] Furthermore, an inclination measuring device is installed for the retaining structure, and an axial force monitoring device is installed for the horizontal support near the bottom of the pit.

[0022] The prestressing system also includes a prestressing control computer. The top support device and the elevation adjustment device are both controlled by the prestressing control computer. The inclination measuring device and the axial force monitoring device are signal-connected to the prestressing control computer.

[0023] The prestress control computer can control the top support device and elevation adjustment device to apply top support prestress to the near bottom of the retaining wall based on the detection data of the inclinometer and axial force monitoring device.

[0024] Furthermore, the top support base is assembled at the connection point between the horizontal support and the pull-out device near the bottom of the pit.

[0025] Furthermore, the number of top support devices is two, and the top support bases of the two top support devices are respectively placed on both sides of the horizontal support near the bottom of the pit. The top support bases of the two top support devices are connected together by fasteners, and the top support bases of the two top support devices hug each other to the horizontal support near the bottom of the pit, thereby realizing the installation of the top support bases on the horizontal support near the bottom of the pit.

[0026] Furthermore, the angle adjustment mechanism is specifically implemented as follows: an angle-adjusting winch is configured for the top support telescopic arm. The angle-adjusting winch is installed on a horizontal support near the bottom of the pit. The winch rope of the angle-adjusting winch is connected to the top support output end of the top support telescopic arm. The winch lifting and lowering action of the angle-adjusting winch can drive the top support telescopic arm to swing up and down.

[0027] Furthermore, the angle-adjusting winch and the height-adjusting winch are the same winch.

[0028] A method for applying prestress to the retaining wall within a foundation pit, the method comprising:

[0029] S1, construct horizontal support near the bottom of the pit;

[0030] S2, a prestressing system is installed based on horizontal supports near the bottom of the pit, and the installation of the prestressing system is completed before the subsequent excavation work of the next lower level;

[0031] The prestressing system includes a top support device;

[0032] The top support device includes a top support base and a top support telescopic arm;

[0033] One end of the top support telescopic arm serves as the assembly end, and the other end of the top support telescopic arm serves as the top support output end;

[0034] The assembly end of the top support telescopic arm is assembled and connected to the top support base.

[0035] The top support telescopic arm is equipped with an angle adjustment mechanism, which is used to drive the top support telescopic arm to swing up and down.

[0036] The top support base of the top support device is mounted on the horizontal support near the bottom of the pit, and the top support output end of the top support telescopic arm can extend toward the bottom of the pit and apply top support prestress to the bottom of the pit.

[0037] S3, apply top support prestress to the retaining structure near the bottom of the pit using a prestressing system;

[0038] The top support output end of the top support telescopic arm of the control top support device extends toward the bottom of the enclosure and applies top support prestress to the bottom of the enclosure.

[0039] Furthermore, the prestressing system also includes an elevation adjustment device;

[0040] The elevation adjustment device includes a support base and an elevation adjustment winch.

[0041] The support seat is placed against the bottom of the enclosure near the pit, and the height adjustment winch is used to drive the support seat to move up and down against the bottom of the enclosure near the pit.

[0042] The top support output end of the top support telescopic arm applies top support prestress to the enclosure near the bottom of the pit through the bearing seat;

[0043] Before applying prestress to the support structure near the bottom of the pit, control the elevation adjustment device to move the bearing seat to the target elevation position for prestress application.

[0044] Then, control the jacking device so that the output end of the jacking telescopic arm abuts against the support seat.

[0045] The top support output end of the top support telescopic arm of the control top support device applies top support prestress to the bottom of the enclosure near the pit through the bearing seat.

[0046] Furthermore, when applying top support prestress to the retaining wall near the bottom of the pit, the deformation of the retaining wall near the bottom of the pit is detected. Based on the deformation of the retaining wall near the bottom of the pit, the top support device is controlled to apply appropriate top support prestress to the retaining wall near the bottom of the pit so that the deformation of the retaining wall near the bottom of the pit meets the design standards.

[0047] Furthermore, when installing the prestressing system, first excavate the soil near the bottom of the pit to remove the soil near the bottom of the pit.

[0048] The main advantages of the prestressing application system and method of the present invention compared with the prior art are as follows:

[0049] After the construction of the horizontal support near the bottom of the pit is completed, the prestressing system is immediately installed based on the horizontal support and installed before the subsequent excavation of the next layer. The prestressing system can apply top support prestress to the retaining wall near the bottom of the pit based on the horizontal support. In this way, the retaining wall near the bottom of the pit can receive the applied top support prestress in the first time, so that the displacement deformation of the retaining wall near the bottom of the pit can be controlled in a timely manner, thereby improving the overall engineering quality of the foundation pit project. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the prestressing system for applying prestress to the retaining wall within the foundation pit according to the present invention;

[0051] Figure 2 For based on Figure 1 A top view of the horizontal support near the bottom of the pit. Detailed Implementation

[0052] First, to facilitate a clear and accurate description of the technical solution later in the text, the following definitions are made in advance:

[0053] Definition 1: The “current pit bottom” mentioned in this article refers to the bottom of the pit during the excavation process of foundation pit construction. The “current pit bottom” is a dynamic concept. Wherever the foundation pit is excavated, that is the “current pit bottom”.

[0054] Definition 2: The “design pit bottom” mentioned in this article refers to the bottom of the foundation pit in the foundation pit engineering design. The “design pit bottom” is a static concept.

[0055] Definition 3: The term "near the bottom of the pit" as used in this article refers to the part of the retaining structure that is close to the current pit bottom (e.g., Figure 1 (Pointed by the middle arrow A). The "retaining structure near the bottom of the pit" is a dynamic concept that changes with the current position of the pit bottom. For example, when the "current pit bottom" is excavated to a depth of 1 meter, the part of the retaining structure at a depth of 1 meter is the "retaining structure near the bottom of the pit".

[0056] Definition 4: The "near-bottom horizontal support" mentioned in this article refers to the horizontal support structure that has been constructed within the foundation pit and is closest to the current pit bottom. This "near-bottom horizontal support" is a dynamic concept. For example, when the first layer of horizontal support structure is completed, this first layer of horizontal support structure is the near-bottom horizontal support; when the second layer of horizontal support structure is completed, this second layer of horizontal support structure is the near-bottom horizontal support, while the first layer of horizontal support structure is no longer the near-bottom horizontal support.

[0057] Definition 5: The “retaining support system” mentioned in this article is a broad concept that encompasses all forms of “support structures” and their combinations within the foundation pit that support the retaining structure, such as “upward-sloping support structures” and “horizontal support structures”.

[0058] Definition 6: The "lower-level foundation pit structure" mentioned in this article refers to the deeper foundation pit structure that will be constructed in the next stage of foundation pit construction. This "lower-level foundation pit structure" is a dynamic concept. For example, if the foundation pit is designed with two layers of horizontal support structures, after the first layer of horizontal support structure is constructed, the second layer of horizontal support structure to be constructed next is the lower-level foundation pit structure. After the second layer of horizontal support structure is constructed, the foundation pit bottom structure to be constructed next is also the lower-level foundation pit structure.

[0059] Definition 7: The term "lower-level excavation work" as used in this article refers to the excavation work performed during the construction of a foundation pit before the construction of a deeper layer of the pit structure. This excavation is necessary to create space for the deeper layer of the foundation pit structure. For example, if a foundation pit is designed with two layers of horizontal support structures, after the first layer is completed, excavation is required to create space for the second layer. This excavation work is considered a lower-level excavation operation.

[0060] The main concept of this invention is:

[0061] Based on the horizontal support near the bottom of the pit, a downwardly inclined support component is installed towards the pit retaining structure. This downwardly inclined support component supports the retaining structure near the bottom of the pit. Then, a supporting force-applying mechanism is installed for the downwardly inclined support component, which can drive the downwardly inclined support component to apply supporting prestress to the retaining structure near the bottom of the pit.

[0062] The main concept of this invention is as described above. In this way, prestressed top support can be applied to the retaining wall near the bottom of the pit before the lower-level foundation pit structure is completed, so as to take corresponding measures to deal with the possible displacement and deformation of the retaining wall near the bottom of the pit in a timely manner, thereby improving the overall engineering quality of the foundation pit project.

[0063] The concept of the present invention will be further illustrated below with specific embodiments:

[0064] See Figure 1 The following is a brief introduction to the foundation pit engineering structure involved in this embodiment.

[0065] Those skilled in the art will understand that the overall engineering structure of the foundation pit mainly includes the retaining structure 6 and the retaining support system, the specific structural configuration of which is as follows:

[0066] The retaining structure 6 is constructed around the perimeter of the foundation pit, and the retaining support system is usually set inside the foundation pit to provide support for the retaining structure 6.

[0067] In this embodiment, the retaining structure 6 is a pile retaining structure.

[0068] The enclosure support system mainly consists of two layers of horizontal support structures 4.

[0069] The two-layer horizontal support structure 4 is installed inside the foundation pit, providing support for the retaining structure 6. For each layer of horizontal support structure 4, a corresponding waler 7 is installed on the retaining structure 6. The waler 7 for the pit top horizontal support structure 4 is located at the top of the retaining structure 6, while the waler 7 for the pit interior horizontal support structure 4 is located on the free side of the retaining structure 6. Both layers of horizontal support structure 4 are connected to the retaining structure 6 via walers 7, thus providing support for the retaining structure 6.

[0070] In this embodiment, the retaining support system also includes a certain number of pull-out devices 5, which are fixedly installed in the foundation pit. Then, the two-layer horizontal support structure 4 mentioned above is connected to the pull-out devices 5, which provide vertical support for the horizontal support structure 4.

[0071] Furthermore, in order to conveniently detect the displacement and deformation of the enclosure structure 6 and obtain the corresponding data, in this embodiment, a clinometer tube 8 (existing technology) is pre-embedded inside the enclosure structure 6, and an intelligent clinometer device 81 is configured for the clinometer tube 8. Through the combination of the clinometer tube 8 and the intelligent clinometer device 81, the displacement and deformation data (tilt) of the enclosure structure 6 can be detected and obtained. For ease of description, the combination of the clinometer tube 8 and the intelligent clinometer device 81 is referred to as the clinometer device.

[0072] In addition, an axial force monitoring device 43 is also installed in the horizontal support structure 4. The axial force monitoring device 43 is used to monitor the horizontal axial force of the horizontal support structure 4, thereby providing data for applying the top support prestress to the top support device 1.

[0073] Those skilled in the art will understand that the above-described foundation pit engineering structure is a structure of the prior art.

[0074] See Figure 1 and Figure 2 This embodiment provides a prestressing system based on the foundation pit engineering structure. This prestressing system is mainly used to apply top-support prestress to the retaining structure 6, especially to apply top-support prestress near the bottom of the pit.

[0075] Specifically

[0076] The prestressing system of this embodiment mainly consists of two parts: a top support device 1 and an elevation adjustment device.

[0077] In this embodiment, two top support devices 1 are provided, and both top support devices 1 are installed based on the horizontal support 41 near the bottom of the pit.

[0078] Regarding the single support device 1,

[0079] The top support device 1 mainly includes a top support base 11 and a top support telescopic arm 12. The top support base 11 needs to be assembled on the horizontal support structure 4, therefore, its overall configuration matches the horizontal support structure 4. In this embodiment, the top support bases 11 of the two top support devices 1 are respectively placed on both sides of a support in the horizontal support structure 4, and the top support bases 11 of the two top support devices 1 are firmly connected together by pins 112. The top support bases 11 of the two top support devices 1 tightly hug the support, thereby realizing the fixed installation of the top support base 11 on the horizontal support structure 4.

[0080] In addition, pre-embedded steel components can be used to connect and assemble the top support base 11 and the horizontal support structure 4. The specific assembly and connection method between the top support base 11 and the horizontal support structure 4 can be determined according to the actual situation.

[0081] The top support telescopic arm 12 is installed based on the top support base 11.

[0082] One end of the top support telescopic arm 12 (usually the body end) serves as the assembly end, and the other end of the top support telescopic arm 12 (usually the telescopic end) serves as the top support output end.

[0083] The mounting end of the top support telescopic arm 12 is connected to the top support base 11 via a shaft pin mechanism, and an angle adjustment mechanism is provided for the top support telescopic arm 12. This angle adjustment mechanism is used to drive the top support telescopic arm 12 to swing up and down based on the top support base 11, so as to adjust the angle of the top support output end of the top support telescopic arm 12 toward the bottom of the enclosure near the pit.

[0084] It should be noted that, in this embodiment, the angle adjustment mechanism is specifically implemented as follows:

[0085] A winch, referred to as an "angle-adjusting winch," is installed on the top support telescopic boom 12. The angle-adjusting winch 24 is mounted on the horizontal support 41 near the bottom of the pit, and its winch rope is connected to the top support output end of the top support telescopic boom 12. In this way, the winching and lifting action of the angle-adjusting winch 24 can drive the top support telescopic boom 12 to swing up and down.

[0086] It should be noted that the angle-adjusting winch 24 has a rotation counter (commonly known as an encoder), which is beneficial for accurately adjusting the swing angle of the top support telescopic arm 12.

[0087] It should be noted that some pulley systems need to be installed for the winch rope of the angle-adjusting winch 24 in order to achieve the turning of the winch rope.

[0088] In other embodiments, other structural forms can also be used to realize the angle adjustment mechanism, as long as the function of "driving the top support telescopic arm 12 to swing up and down based on the top support base 11 to adjust the angle of the top support output end of the top support telescopic arm 12 toward the bottom of the enclosure" can be achieved. This invention does not limit this.

[0089] The top support output end of the top support telescopic arm 12 serves as the top support output end of the entire top support device 1 and is used to output the top support force outward.

[0090] It should be noted that in this embodiment, the top support telescopic arm 12 is a two-section hydraulic telescopic rod, which is composed of a large hydraulic loading sleeve combined with a telescopic rod body, which is fully understandable to those skilled in the art.

[0091] Other forms of telescopic booms can be used in other implementations, as long as they can achieve the effect of "being able to extend and retract, and being able to output a strong supporting force." For example, an electric telescopic boom can be used.

[0092] In addition, a top support end 13 is provided at the top support output end of the top support telescopic arm 12. The top support end 13 is assembled on the top support output end of the top support telescopic arm 12 through a shaft pin mechanism. The top support end 13 can swing up and down based on the top support output end of the top support telescopic arm 12. The configuration of the top support end 13 matches the bearing surface 221 of the bearing seat 22, which will be mentioned later.

[0093] The elevation adjustment device includes a support base 22, and a winch is configured for the support base 22, which is referred to as the "elevation adjustment winch".

[0094] The support base 22 is connected to the winch rope 231 (steel strand) of the height-adjusting winch 23, which is used to perform winch lifting and lowering operations on the support base 22. When the height-adjusting winch 23 is installed on the horizontal support structure 4, the height-adjusting winch 23 can perform winch lifting and lowering operations on the support base 22 based on the horizontal support structure 4.

[0095] It should be noted that the height-adjusting winch 23 has a rotation counter (commonly known as an encoder), which is beneficial for accurately adjusting the lifting height of the winch.

[0096] The support seat 22 also has a support surface for receiving the support of the support telescopic arm 12 of the support device 1.

[0097] It should be noted that the height-adjusting winch 23 and the angle-adjusting winch 24 can be implemented using the same winch. Specifically, the winch is equipped with two independent winch ropes, one of which is connected to the support seat 22, and the other is connected to the top support telescopic arm 12. In this way, the winch can adjust both the height of the support seat 22 and the swing angle of the top support telescopic arm 12, and the two adjustments are synchronized, thereby simplifying the equipment configuration and the operation process.

[0098] It should be noted that the prestressing system in this embodiment is mainly used to apply top support prestress to the retaining wall near the bottom of the pit. Therefore, the top support device 1 and the elevation adjustment device are mainly installed based on the horizontal support 41 near the bottom of the pit.

[0099] Specifically

[0100] The top support base 11 of the top support device 1 is mounted on the horizontal support 41 near the bottom of the pit. The top support telescopic arm 12 of the top support device 1 can extend obliquely downward toward the enclosure structure 6, and the top support output end of the top support telescopic arm 12 is obliquely downward toward the enclosure near the bottom of the pit.

[0101] The elevation adjustment device's height adjustment winch 23 is installed on the horizontal support 41 near the bottom of the pit. The support seat 22 of the elevation adjustment device is located below the horizontal support 41 near the bottom of the pit. The horizontal support structure 4 separates the height adjustment winch 23 from the support seat 22.

[0102] The support seat 22 is placed against the bottom of the enclosure near the pit, and the height adjustment winch 23 can drive the support seat 22 to move up and down against the bottom of the enclosure near the pit.

[0103] It should be noted that the hoisting rope 231 of the height adjustment winch 23 needs to pass through the horizontal support 41 near the bottom of the pit before it can be connected to the support seat 22. Therefore, a penetrating pipe 29 is provided at the corresponding position near the bottom of the pit in the enclosure. After the hoisting rope 231 of the height adjustment winch 23 passes through the penetrating pipe 29, it can be connected to the support seat 22 and drive the support seat 22 to move up and down.

[0104] It should be noted that some pulley systems need to be set up for the hoisting rope 231 of the height adjustment winch 23 to realize the turning of the hoisting rope 231, thereby realizing the "up and down movement of the support seat 22 against the bottom of the pit". This is clear to those skilled in the art, so it will not be described in detail.

[0105] It should be noted that in other embodiments, the height adjustment winch 23 does not need to be installed on the horizontal support 41 near the bottom of the pit. It can also be installed in other parts of the pit structure, as long as it can achieve the goal of "the height adjustment winch 23 being able to drive the support seat 22 to move up and down against the bottom of the enclosure".

[0106] The elevation adjustment device is used to install a support seat 22 at the top support position near the bottom of the pit in the retaining structure. The top support force applied by the top support device 1 is applied to the retaining structure 6 through the support seat 22.

[0107] Since the retaining structure 6 involved in this embodiment is a pile row retaining structure, the applied top support force acts on the pile row retaining structure through the bearing seat 22, which can make the entire pile row retaining structure bear force evenly.

[0108] When it is necessary to apply top support prestress to the target prestressing elevation position near the bottom of the pit in the retaining structure, the winch 23 is raised to move the bearing seat 22 to the target prestressing elevation position. Then, the top support output end of the top support telescopic arm 12 of the top support device 1 is extended and supported on the bearing seat 22. The top support force applied by the top support device 1 is then transmitted to the bottom of the pit in the retaining structure through the bearing seat 22, thereby realizing the application of top support prestress.

[0109] Furthermore, the support seat 22 also has a support surface 221. When the support seat 22 is against the bottom of the enclosure, the support surface 221 faces the location of the top support device 1. This support surface 221 is used to receive the pressure from the top support output end (top support end 13) of the top support telescopic arm 12 of the top support device 1. The top support force applied by the top support device 1 can be transmitted to the bottom of the enclosure through the support seat 22. The support surface 221 is slightly inclined upward, or in other words, the support surface 221 is slightly inclined towards the top support base 11 of the top support device 1, so as to receive the pressure from the top support telescopic arm 12 of the top support device 1 as directly as possible.

[0110] It should be noted that the configuration of the bearing surface 221 of the support seat 22 matches the configuration of the top support end 13 mentioned earlier. In this way, when the top support output end of the top support telescopic arm 12 presses against the bearing surface 221 of the support seat 22, the top support end 13 can fit together with the bearing surface 221 of the support seat 22, and the friction between the two will be very large, so that the top support output end of the top support telescopic arm 12 can be stably supported on the support seat 22.

[0111] The prestressing system in this embodiment also includes a prestressing control computer. The electrical equipment, such as the jacking device 1 and the elevation adjustment device, are all controlled by the prestressing control computer, and the inclinometer and axial force monitoring device 43 are also signal-connected to the prestressing control computer. In this way, the prestressing control computer can control the jacking device 1 and the elevation adjustment device, etc., to apply jacking prestress to the area near the bottom of the pit based on the detection data from the inclinometer and axial force monitoring device 43. Furthermore, the prestressing control computer contains a control program for applying jacking prestress, thereby achieving intelligent control of "controlling the jacking device 1 and the elevation adjustment device to apply jacking prestress to the area near the bottom of the pit based on the detection data from the inclinometer and axial force monitoring device 43."

[0112] This embodiment also provides a method for applying prestress to the retaining wall within the excavation pit. This method is used to achieve "applying top support prestress to the retaining wall near the bottom of the pit." In essence, this method is implemented using the concept of the prestressing system described earlier.

[0113] Specifically, the method for applying prestress in this embodiment includes:

[0114] S1, construct a horizontal support 41 near the bottom of the pit at the construction location of the foundation pit.

[0115] It should be noted that the near-bottom horizontal support 41 is constructed based on the pull-out device 5 pre-built in the foundation pit.

[0116] The constructed near-bottom horizontal support 41 is as described above and will not be repeated here.

[0117] S2, after the construction of the near-bottom horizontal support 41 is completed in step S1, the prestressing system is immediately installed based on the near-bottom horizontal support 41, and the installation of the prestressing system is completed before the subsequent excavation work of the next layer.

[0118] The specific installation structure of the prestressing system is as described above and will not be repeated here.

[0119] It should be noted that when installing the prestressing system, it is necessary to first excavate the soil near the bottom of the pit and remove the soil near the bottom of the pit. The purpose of this is to provide operating space for "the elevation adjustment device to move the support seat 22 downward to the bottom of the pit, the top support telescopic arm 12 of the top support device 1 to swing downward toward the bearing surface of the support seat 22, and then make the top support output end of the top support telescopic arm 12 abut against the bearing surface of the support seat 22".

[0120] It should be noted that "excavating soil near the bottom of the pit" here does not fall under the category of "lower-level excavation work".

[0121] S3, apply top support prestress to the near-bottom area of ​​the retaining wall using a prestressing system.

[0122] Specifically

[0123] Determine the target elevation for prestressing application near the bottom of the pit in the retaining wall;

[0124] Control the elevation adjustment device to move the bearing seat 22 to the target elevation position for prestressing application;

[0125] The support telescopic arm 12 of the control support device 1 extends obliquely downward toward the bottom of the pit in the retaining structure. In particular, the support output end of the support telescopic arm 12 should be directed toward the bearing seat 22 at the target elevation position for prestressing. The control support device 1 should be adjusted so that the support end 13 on the support output end of the support telescopic arm 12 abuts against the bearing surface 221 of the bearing seat 22. The support force applied by the support telescopic arm 12 of the control support device 1 is then applied to the target elevation position for prestressing near the bottom of the pit in the retaining structure through the bearing seat 22.

[0126] The aforementioned inclinometer device is used to detect the deformation status (deformation data) of the retaining wall near the bottom of the pit. Based on the deformation status of the retaining wall near the bottom of the pit and in accordance with the design standards, the top support device 1 is controlled to apply appropriate top support prestress to the retaining wall near the bottom of the pit so that the deformation status of the retaining wall near the bottom of the pit meets the design standards.

[0127] Thus, the prestressing method of this embodiment achieves the effect of "precisely applying top support prestress at the target elevation position of prestressing application near the bottom of the pit in the retaining structure".

[0128] It should be noted that for the entire control process of step S3, a pre-designed software control program is set in the prestressed control computer. The entire control process of step S3 is essentially controlled and implemented by the prestressed control computer according to the pre-designed software control program.

[0129] Once the prestressing method is completed, the excavation work for the next layer can begin.

[0130] It should be noted that, in this embodiment, the top support device 1 is assembled at the connection between the horizontal support structure 4 and the pull-out resisting device 5. The top support base 11 of the top support device 1 can be assembled and connected to the pull-out resisting device 5 through pins or pre-embedded steel components. In this way, the top support device 1 can obtain strong vertical support when the top support prestress is applied, and the horizontal support structure 4 will not deform due to the reaction force caused by the top support prestress applied by the top support device 1.

[0131] It should be noted that in other embodiments, the elevation adjustment device is not necessary. In other embodiments, if the enclosure structure 6 is a continuous wall enclosure structure, the elevation adjustment device may not be provided, and the top support output end of the top support telescopic arm 12 of the top support device 1 can directly abut against the enclosure structure 6.

[0132] It should be noted that the load-bearing seat 22 can be made of concrete or precast steel.

[0133] It should be noted that the prestressing system can be applied to the entire enclosure structure or to a portion of the enclosure structure.

[0134] It should be noted that the prestressing system and prestressing method of this embodiment can be implemented not only for a single-layer horizontal support structure 4, but also for multiple-layer horizontal support structures 4.

[0135] The main advantages of the prestressing system and prestressing method of this embodiment are:

[0136] 1) After the construction of the near-bottom horizontal support 41 is completed, the prestressing system shall be installed immediately based on the near-bottom horizontal support 41 and the installation of the prestressing system shall be completed before the subsequent excavation of the next layer.

[0137] The top support device 1 in the prestressing system has a top support telescopic arm 12. The top support output end of the top support telescopic arm 12 can extend obliquely downward toward the bottom of the enclosure and apply top support prestress to the bottom of the enclosure.

[0138] In this way, the retaining wall near the bottom of the pit can be subjected to top support prestress in the first instance, so that the displacement and deformation of the retaining wall near the bottom of the pit can be corrected in a timely manner, thereby improving the overall engineering quality of the foundation pit project.

[0139] Furthermore, the prestressing system and prestressing method of this embodiment have the following advantages:

[0140] 2) No pre-embedded parts are required in the early stage, and installation can be carried out at any time. The installation is flexible and does not require any special structural settings beforehand.

[0141] 3) The prestressing application system can intelligently determine the target elevation position of prestressing application on the near bottom of the pit based on the inclination measurement data of the inclination measuring device. This allows for more precise control of the force and direction of the prestressing applied by the top support device 1 during construction.

[0142] 4) The prestressing system and prestressing method described above can effectively apply top support prestress to the retaining wall near the bottom of the pit, thereby effectively controlling the deformation of the retaining wall near the bottom of the pit and improving the safety and reliability of the foundation pit construction.

[0143] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A prestressing system for applying prestress to the retaining wall within a foundation pit, characterized in that: The prestressing system includes a top support device (1); The top support device (1) includes a top support base (11) and a top support telescopic arm (12); One end of the top support telescopic arm (12) serves as the assembly end, and the other end of the top support telescopic arm (12) serves as the top support output end; The assembly end of the top support telescopic arm (12) is assembled and connected to the top support base (11). An angle adjustment mechanism is provided for the top support telescopic arm (12), which is used to drive the top support telescopic arm (12) to swing up and down. The top support base (11) of the top support device (1) is mounted on the horizontal support (41) near the bottom of the pit, and the top support output end of the top support telescopic arm (12) can extend toward the bottom of the pit and apply top support prestress to the bottom of the pit. The prestressing system also includes an elevation adjustment device; The elevation adjustment device includes a support base (22) and an elevation adjustment winch (23). The bearing seat (22) is placed against the bottom of the enclosure near the pit, and the height adjustment winch (23) is used to drive the bearing seat (22) to move up and down against the bottom of the enclosure near the pit. The top support output end of the top support telescopic arm (12) applies top support prestress to the bottom of the enclosure near the pit through the bearing seat (22); The angle adjustment mechanism is specifically implemented as follows: an angle adjustment winch (24) is configured for the top support telescopic arm (12). The angle adjustment winch (24) is installed on the horizontal support (41) near the bottom of the pit. The winch rope of the angle adjustment winch (24) is connected to the top support output end of the top support telescopic arm (12). The winch lifting action of the angle adjustment winch (24) can drive the top support telescopic arm (12) to swing up and down.

2. The prestressing system for applying prestress to the retaining wall within the foundation pit according to claim 1, characterized in that: The height adjustment winch (23) is installed on the horizontal support (41) near the bottom of the pit.

3. The prestressing system for applying prestress to the retaining wall within the foundation pit according to claim 1, characterized in that: The bearing seat (22) has a bearing surface (221), which is inclined upward and faces the top support base (11) of the top support device (1).

4. The prestressing system for the retaining wall within the foundation pit according to claim 3, characterized in that: The top support output end of the top support telescopic arm (12) is provided with a top support head (13), which is assembled on the top support output end of the top support telescopic arm (12) through a shaft pin mechanism.

5. The prestressing system for the retaining wall within the foundation pit according to claim 1, characterized in that: An inclination measuring device is installed for the retaining structure (6), and an axial force monitoring device (43) is installed for the horizontal support (41) near the bottom of the pit; The prestressing system also includes a prestressing control computer. The top support device (1) and the elevation adjustment device are both controlled by the prestressing control computer. The inclination measuring device and the axial force monitoring device (43) are connected to the prestressing control computer via signal. The prestress control computer can control the top support device (1) and the elevation adjustment device to apply top support prestress to the bottom of the retaining wall based on the detection data of the inclinometer and axial force monitoring device (43).

6. The prestressing system for the retaining wall within the foundation pit according to claim 1, characterized in that: The top support base (11) is assembled at the connection between the horizontal support (41) near the bottom of the pit and the pull-out device (5).

7. The prestressing system for applying prestress to the retaining wall within the foundation pit according to claim 1, characterized in that: The number of top support devices (1) is two. The top support bases (11) of the two top support devices (1) are respectively placed on both sides of the horizontal support (41) near the bottom of the pit. The top support bases (11) of the two top support devices (1) are connected together by fasteners. The top support bases (11) of the two top support devices (1) hug each other to the horizontal support (41) near the bottom of the pit, thereby realizing the installation of the top support bases (11) on the horizontal support (41) near the bottom of the pit.

8. The prestressing system for the retaining wall within the foundation pit according to claim 1, characterized in that: The angle-adjusting winch (24) and the height-adjusting winch (23) are the same winch.

9. A method for applying prestress to the retaining wall within a foundation pit, characterized in that: The method for applying prestress includes: S1, construct a horizontal support near the bottom of the pit (41); S2, based on the horizontal support (41) near the bottom of the pit, install a prestressing system for the retaining wall in the pit as described in any one of claims 1 to 8, and complete the installation of the prestressing system before the subsequent excavation of the next lower level. S3, apply top support prestress to the retaining structure near the bottom of the pit using a prestressing system; The top support output end of the top support telescopic arm (12) of the control top support device (1) extends toward the bottom of the enclosure and applies top support prestress to the bottom of the enclosure.

10. The method for applying prestress to the retaining wall within the foundation pit according to claim 9, characterized in that: Before applying prestress to the top support near the bottom of the pit, control the elevation adjustment device to move the bearing seat (22) to the target elevation position for prestress application. Then, control the top support device (1) so that the top support output end of the top support telescopic arm (12) abuts against the support seat (22). The top support output end of the top support telescopic arm (12) of the control top support device (1) applies top support prestress to the bottom of the enclosure near the pit through the bearing seat (22).

11. The method for applying prestress to the retaining wall within the foundation pit according to claim 9, characterized in that: When applying the top support prestress to the bottom of the retaining wall near the pit, the deformation of the bottom of the retaining wall near the pit is detected. Based on the deformation of the bottom of the retaining wall near the pit, the top support device (1) is controlled to apply appropriate top support prestress to the bottom of the retaining wall near the pit so that the deformation of the bottom of the retaining wall near the pit meets the design standards.

12. The method for applying prestress to the retaining wall within the foundation pit according to claim 9, characterized in that: When installing the prestressing system, first excavate the soil near the bottom of the pit to remove the soil near the bottom of the pit.

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