CN216551960U

CN216551960U - Supporting structure of foundation pit adjacent to existing building

Info

Publication number: CN216551960U
Application number: CN202123086421.5U
Authority: CN
Inventors: 李建旺; 伍天华; 郭建伟; 王涛; 孙浩; 牛俊涛; 高永涛; 杨璐; 张之耀; 李军; 兀益哲
Original assignee: University of Science and Technology Beijing USTB; Urban Rail Transit Engineering Co Ltd of China Railway 15th Bureau Group Co Ltd
Current assignee: University of Science and Technology Beijing USTB; Urban Rail Transit Engineering Co Ltd of China Railway 15th Bureau Group Co Ltd
Priority date: 2021-12-09
Filing date: 2021-12-09
Publication date: 2022-05-17
Anticipated expiration: 2031-12-09

Abstract

The utility model provides a supporting construction of neighbouring foundation ditch of existing building, wherein, the foundation ditch includes the first sub foundation ditch that is close to existing building and keeps away from the second sub foundation ditch of existing building, and supporting construction of foundation ditch includes: the underground continuous wall is arranged around the side wall of the foundation pit; the supporting component is arranged in the foundation pit and used for supporting the foundation pit; and the temporary covering layer covers the top of the first sub-foundation pit. The foundation pit supporting structure adjacent to the existing building can strictly control the deformation of the adjacent existing building or structure, particularly the historic building group protected by the historic building, and control the deformation of the foundation pit.

Description

Supporting structure of foundation pit adjacent to existing building

Technical Field

The utility model relates to a civil construction engineering technical field especially relates to a supporting construction of foundation ditch of neighbouring existing building.

Background

In recent years, urban rail transit construction has been developed vigorously, which has become one of effective measures for coping with urban traffic congestion. Accordingly, the construction of deep and large foundation pits of rail transit stations is also becoming more and more common. However, the construction position of the foundation pit of the rail transit station or the tunnel is often difficult to avoid adjacent surrounding existing buildings/structures, and disturbance is inevitably generated on surrounding soil bodies and the buildings/structures in the process of excavation unloading of the foundation pit, so that the safety and stability of the existing buildings/structures are influenced. Particularly, when the deep foundation pit of the station is excavated and constructed on the ancient buildings in the protection areas adjacent to the key cultural relics, the ancient buildings and the cultural relics in the conservation areas have special and important scientific research values, compared with common buildings, the protection level and the deformation control standard of the ancient buildings are higher, and higher requirements and challenges are undoubtedly provided for the deformation control of the deep foundation pit construction.

SUMMERY OF THE UTILITY MODEL

Some embodiments of the present disclosure provide a supporting structure adjacent to a foundation pit of an existing building, which can achieve strict control of deformation of the adjacent existing building or structure, particularly, a historic building group for cultural relics protection, and control of deformation of the foundation pit itself.

The utility model provides a foundation ditch supporting construction is applicable to the foundation ditch of neighbouring existing building, and the foundation ditch includes the first sub-foundation ditch that is close to existing building and keeps away from the sub-foundation ditch of second of existing building, and foundation ditch supporting construction includes: the underground continuous wall is arranged around the side wall of the foundation pit; the supporting component is arranged in the foundation pit and used for supporting the foundation pit; and the temporary covering layer covers the top of the first sub-foundation pit. For the existing buildings located in the reinforcing range, a soil body reinforcing structure is arranged below the existing buildings; the reinforcement range comprises a range which is located outside the side wall of the foundation pit and has a horizontal distance with the side wall of the foundation pit smaller than or equal to 0.7H, wherein H is the average excavation depth of the foundation pit.

In at least one embodiment of the present disclosure, the underground diaphragm wall comprises a plurality of trough sections, each trough section comprising a plurality of wall panels; the supporting construction of foundation ditch still includes: the high-pressure rotary spraying construction method comprises a plurality of high-pressure rotary spraying construction method piles, wherein the high-pressure rotary spraying construction method piles are arranged at an underground continuous wall with the shortest distance of less than 10-12 m to an existing building, and one high-pressure rotary spraying construction method pile is correspondingly arranged at the joint between every two adjacent wall panels.

In at least one embodiment of the present disclosure, the soil reinforcing structure is located 2m to 3m vertically below the foundation of the existing building.

In at least one embodiment of the present disclosure, a support assembly includes: and multiple supports are arranged at intervals along the depth direction of the foundation pit. Wherein, the first support near the top of the foundation pit is a concrete support; the second support to the Nth support are sequentially arranged below the first support at intervals, and the second support to the Nth support are all servo steel supports; wherein N is a positive integer greater than or equal to 2.

In at least one embodiment of the present disclosure, the foundation pit supporting structure further includes: and the supporting shaft force servo compensation system is connected with the second to the Nth supports. The support axis force servo compensation system is configured to: applying pre-applied axial force to the second support to the Nth support respectively; and applying axial force to the second support to the Nth support in a grading manner according to the construction progress, and/or applying axial force to the second support to the Nth support according to the deformation condition of the foundation pit and/or the existing building.

In at least one embodiment of the present disclosure, the foundation pit supporting structure further includes: and the monitoring system is connected with the supporting shaft force servo compensation system. The monitoring system is configured to monitor deformation conditions of the foundation pit and deformation conditions of the existing building and transmit the monitored data to the support shaft force servo compensation system. Wherein, the deformation condition of existing building includes: at least one of a settlement condition, an inclination condition, a vibration condition, a horizontal displacement condition, and a crack condition of the existing building.

In at least one embodiment of the present disclosure, along a direction in which a center of the foundation pit points to a boundary of the foundation pit, a region outside the foundation pit is sequentially divided into a first affected zone, a second affected zone, and a third affected zone. The shortest distance between the soil body at any position in the first affected area and the foundation pit meets the condition that L is less than or equal to M; the shortest distance between the soil body at any position in the second affected area and the foundation pit meets the condition that M is larger than L and is smaller than or equal to 2M; the shortest distance between the soil body at any position in the third affected area and the foundation pit meets the condition that L is more than 2M; wherein L is the shortest distance between the soil outside the foundation pit and the foundation pit; m is the influence range critical value of foundation ditch excavation, and M is 3H, and H is the average depth of foundation ditch. The monitoring system comprises a plurality of monitoring components, and the monitoring components are arranged in the first influence area, the second influence area, the third influence area and the outer edge of the foundation pit; wherein, in the first influence district, the second influence district and the third influence district, the density of setting of monitoring subassembly reduces in proper order.

In at least one embodiment of the present disclosure, the foundation pit supporting structure further includes: the foundation pit structure comprises a plurality of upright posts arranged in the foundation pit and a plurality of latticed columns which are inserted into the upright posts in a one-to-one correspondence mode.

In at least one embodiment of the present disclosure, the foundation pit support structure further comprises a plurality of dewatering wells; the plurality of dewatering wells include: at least one pit inner drainage well and at least one pit inner depressurization well which are arranged in the foundation pit; and at least one pit water level observation well and recharge well which are arranged on the outer side of the underground continuous wall.

In at least one embodiment of the present disclosure, the foundation pit supporting structure further includes a crown beam disposed at a top surface of the foundation pit.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.

Fig. 1 is a schematic illustration of an excavation supporting structure according to some embodiments;

FIG. 2 is a right side view of the embodiment shown in FIG. 1;

FIG. 3 is a top view of the embodiment shown in FIG. 1;

FIG. 4 is a cross-sectional view taken perpendicular to the X-direction of the embodiment of FIG. 1;

fig. 5 is a schematic view of an underground diaphragm wall of an excavation supporting structure according to some embodiments;

figure 6 is a schematic view of a high pressure jet grouting method pile structure of a foundation pit support structure according to some embodiments;

figure 7 is a schematic illustration of a monitoring system of an excavation supporting structure coupled to a support axial force servo compensation system, in accordance with some embodiments;

FIG. 8 is a flow chart of a method of constructing a foundation pit according to some embodiments;

FIG. 9 is a schematic view of an underground diaphragm wall "three-by-one" construction method according to one method of foundation pit construction in accordance with some embodiments;

FIG. 10 is a plan view of a poor political station pit and a cultural relic protection building group relative to each other for a method of constructing the pit, according to some embodiments;

FIG. 11 is a cross-sectional view of the construction effect of a foundation pit excavated to the substrate according to one method of foundation pit construction according to some embodiments;

fig. 12-18 are process diagrams of the construction of a station body structure within a foundation pit according to some embodiments;

FIG. 19 is a graph comparing displacement of a diaphragm wall at a first monitoring point of a method of constructing a foundation pit, according to some embodiments;

fig. 20 is a graph comparing vertical displacement of the monument security building at the second monitoring point of a method of constructing a foundation pit, according to some embodiments.

Reference numerals:

100-existing building, 110-suzhou museum, 120-clumsiness garden, 200-foundation pit, 201-first sub-foundation pit, 202-second sub-foundation pit, 203-foundation pit bottom, 210-clumsiness garden station foundation pit, 310-underground continuous wall, 311-first sub-underground continuous wall, 312-second sub-underground continuous wall, 313-groove section, 314-wall width, 320-high-pressure jet grouting construction pile, 330-temporary covering layer, 341-upright post pile, 342-lattice column, 350-crown beam, 351-first sub-crown beam, 352-second sub-crown beam, 360-soil body reinforced structure, 370-support axial force servo compensation system, 371-support head assembly, 372-numerical control pump station, 373-host, 381-first concrete support, 382-second servo steel support, 383-a third servo steel support, 384-a fourth servo steel support, 385-a fifth servo steel support, 390-a monitoring system, 391-a cloud service platform, 392-a monitoring component, 393-a settlement monitoring point, 394-a crack monitoring point, 395-a foundation pit deformation monitoring point, 396-a first monitoring point, 397-a second monitoring point, 400-a sleeve valve grouting pipe, 500-a top compression beam and 600-a confined aquifer.

Detailed Description

The present disclosure will be described in further detail with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not to be construed as limitations of the present disclosure. It should be further noted that, for the convenience of description, only the portions relevant to the present disclosure are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.

It should be noted that, the step numbers in the text are only for convenience of explanation of the specific embodiments, and do not serve to limit the execution sequence of the steps.

As described in the background art, the excavation of the foundation pit may have a certain influence on the existing buildings or structures around the foundation pit, and the influence range is large, and corresponding control measures need to be made and taken in the design and construction stages of the foundation pit structure. Particularly, for key historical relic and ancient buildings with extremely high requirements on protection level, the traditional foundation pit construction control method is difficult to achieve the protection effect on the adjacent ancient buildings. According to the classification standard of civil building protection classes, the protection grade of historic building protection belongs to I grade (the protection grade is high and important protection is needed), and most common buildings belong to II/III/IV protection grade. The maximum inclination value of the building protected by the I level is required to be less than 3mm, the horizontal deformation value of the building protected by the I level is required to be less than 2mm, and the curvature of the building protected by the I level is required to be less than 0.2. For the same construction engineering disturbance, the maximum deformation value allowed by the civil insurance building is far smaller than that of buildings with other protection grades.

Based on this, some embodiments of the present disclosure provide a supporting structure of a foundation pit adjacent to an existing building and a foundation pit construction method, so as to realize strict control of deformation of the adjacent existing building or structure, especially a historical relic protection ancient building group, and control of deformation of the foundation pit itself.

In the following embodiments, repeated descriptions are not avoided, and some technical features and advantages of the foundation pit supporting structure and corresponding technical features and advantages of the foundation pit supporting structure in the foundation pit construction method may be referred to each other.

In the present specification, an existing building or structure is referred to as an "existing building".

In some embodiments of the present disclosure, the foundation pit to be excavated may be a foundation pit of a station of rail transit (e.g., a subway, etc.), or may be a foundation pit of a tunnel with a shallow buried depth, and the shallow tunnel is excavated by open excavation. The disclosure is described below by taking the foundation pit to be excavated as a subway station foundation pit as an example.

Reference to "adjacent" in some embodiments of the present disclosure means that the shortest horizontal distance between the excavation to be made and the existing building is less than or equal to 3.0H, where H is the average depth of the excavation. In the construction process of the foundation pit to be excavated, corresponding measures are required to be taken for controlling the deformation of the building within the range of 3.0H.

In addition, in some embodiments of the present disclosure, for the newly created pit, the length direction refers to the X direction indicated in the drawing, the width direction refers to the Y direction indicated in the drawing, and the vertical direction, or the depth direction refers to the Z direction indicated in the drawing.

As shown in fig. 1 to 4, some embodiments of the present disclosure provide an excavation supporting structure adapted to an excavation adjacent to an existing building. The foundation pit 200 includes a first sub-foundation pit 201 adjacent to the existing building 100 and a second sub-foundation pit 202 distant from the existing building 100. The foundation ditch supporting construction includes: an underground continuous wall 310 disposed around a sidewall of the foundation pit 200; a support member disposed in the foundation pit 200 and configured to support the foundation pit 200; and a temporary capping layer 330 covering the top of the first sub-foundation pit 201.

According to the foundation pit supporting structure provided by some embodiments of the present disclosure, the temporary covering layer 330 is arranged at the top of the first sub-foundation pit 201 close to the existing building 100, firstly, a temporary road surface can be formed in the construction process of the foundation pit 200, so that the traffic pressure is relieved, and the smooth traffic near the existing building 100 can be ensured while the requirement of traffic fluffing is met. Secondly, the temporary covering layer 330 is applied to make the excavation of the foundation pit 200 be carried out in a construction mode of local (semi) cover excavation, the excavation clearance height of the semi-cover excavation construction method is high, the arrangement of supports (such as steel supports, servo steel supports and the like) in the foundation pit 200 and the arrangement of excavation procedures are simple, the operation is convenient, the construction progress is fast, and the total construction period is greatly shortened. In addition, in the construction mode of local (semi) cover excavation, after the construction of the temporary pavement is completed, the supporting structure in the foundation pit can be formed in sequence according to the design requirement, the construction is convenient, the integrity is good, the generated secondary stress is small, and the disturbance and the influence on the existing building 100 are also greatly reduced.

As shown in fig. 5, in some embodiments of the present disclosure, underground diaphragm wall 310 includes a plurality of trough segments 313, each trough segment 313 including a plurality of wall panels 314.

For the underground continuous wall 310 of the foundation pit 200 near one side of the existing building 100, the high pressure jet grouting method pile 320 may be used for stopping water. Illustratively, as shown in fig. 6, the supporting structure of the foundation pit further includes: the high-pressure rotary spraying method pile 320 is characterized in that the high-pressure rotary spraying method pile 320 is arranged at an underground continuous wall 310 with the shortest distance to the existing building 100 being less than 10 m-12 m, and one high-pressure rotary spraying method pile 320 is correspondingly arranged at the joint between every two adjacent wall panels 314. The high-pressure jet grouting method is adopted for stopping water at the joint of the underground continuous wall 310 through the piles 320, so that deformation of surrounding soil layers and influence on the surrounding existing buildings 100 can be reduced, and safety of surface water levels of the existing buildings 100 can be guaranteed.

In some embodiments of the present disclosure, for an existing building 100 located within a reinforcement range, a soil reinforcement structure 360 is disposed below the existing building 100, and the soil reinforcement structure 360 is located 2m to 3m below a foundation of the existing building 100; the reinforcement range includes a range in which a horizontal distance from the sidewall of the foundation pit 200 outside the sidewall of the foundation pit 200 is less than or equal to 0.7H, where H is an average excavation depth of the foundation pit 200.

Illustratively, the soil reinforcing structure 360 may be implemented by grouting, for example, deep-hole grouting, sleeve valve pipe grouting, or grouting in situ in combination with other grouting methods, so as to reinforce the existing building 100 by grouting and reduce disturbance of foundation pit construction to the existing building.

Taking sleeve valve pipe grouting as an example, before the excavation of the foundation pit 200, for the existing building 100 located within the reinforcement range, a plurality of inclined grouting holes may be drilled at one side or a plurality of sides of the existing building 100, and a plurality of sleeve valve grouting pipes 400 may be pre-buried in the plurality of grouting holes in a one-to-one correspondence manner. Because the foundation forms adopted by different buildings are different, some are pile foundations, some are strip foundations, and the depth of the pile foundations is generally larger than that of the strip foundations. When the existing building 100 is a deep foundation (the foundation burial depth is more than 5m or more than the width of the foundation) structure (such as a pile foundation), the inclination angle of the pre-embedded sleeve valve pipe can be set to be 60-75 degrees; when the building is in a shallow foundation (the foundation burial depth is 3-5 m, or the foundation burial depth is less than the width of the foundation) structure (such as a strip foundation), the inclination angle of the grouting pipe of the embedded sleeve valve can be set to be 40-45 degrees. The end of the sleeve valve grouting pipe 400 may be inserted 2m, 2.3m, 2.5m, 2.7m, or 3m below the bottom surface of the foundation of the existing building 100.

For the construction of the soil body reinforcing structure 360, the partial pre-grouting can be performed on the lower part of the existing building by using the sleeve valve grouting pipe before the excavation of the foundation pit, and the tracking grouting can be performed on the lower part of the existing building by using the sleeve valve grouting pipe after the excavation of the foundation pit to form the soil body reinforcing structure 360.

For example, the local pre-grouting may specifically be performed before excavation, by analyzing a larger risk area that may exist in the excavation process of the foundation pit according to relevant information of the civil insurance building (for example, the boundary of the civil insurance building is only 1-2 m away from the foundation pit to be excavated, or even smaller, or the civil insurance building itself has some obvious cracks due to long time, and may be damaged in a large area due to slight disturbance). And/or before the foundation pit is excavated, adopting finite element software (such as ABAQUS/ANSYS) to simulate potential mechanical behavior characteristics of a building in the process of excavating the foundation pit according to actual working conditions on site by establishing a three-dimensional refined numerical model containing the foundation pit and the existing building. And analyzing the numerical simulation result, and carrying out local grouting reinforcement before excavation on places with large deformation displacement, concentrated stress and obvious plastic region distribution of the building. The grouting amount of the local pre-grouting is, for example, 0.5 to 0.7m³And m, the final grouting pressure is 0.7-0.9 MPa, and grouting can be stopped after the grouting pressure reaches the designed final grouting pressure for 5-6 min. The local pre-grouting before excavation can further reduce the construction risk level in the excavation process of the foundation pit, and the deformation of the existing building is strictly controlled. The follow-up grouting may be, for example, performed during excavation of the foundation pit 200,and (3) reinforcing the soil layer by adopting a tracking grouting mode according to the deformation conditions of the existing building 100 and the foundation pit 200 by monitoring the deformation data of the existing building 100 and the foundation pit 200 in real time. For example, the preset control value of the settlement and horizontal deformation of the existing building 100 is 5mm, and the preset control value of the inclined deformation is 3 ‰. When the settlement deformation, the horizontal displacement, the inclination amount and the like of the existing building 100 reach 60% of the preset control values, the excavation construction of the foundation pit 200 is firstly suspended, the structural support axial force of the foundation pit 200 is improved, and the tracking compensation grouting operation is carried out. The grouting amount is 0.8-1.0m³The grouting pressure is 1.50-2.0MPa, and the grouting speed is 10-35L/min. And stopping grouting when the deformation value of the deformation index tends to be stable (the deformation value does not change any more) and is within a controllable range. For the civil insurance building group, the civil insurance building group has extremely high control requirement on deformation, so that grouting operation can be performed in advance through early warning of deformation. According to the real-time monitoring feedback of the deformation of the building, grouting parameters are strictly controlled and adjusted, and the deformation of the civil insurance building can be reduced to the greatest extent.

When the disturbance of excavation of foundation pit 200 to surrounding building crowd is too big, form soil body reinforced structure 360 through carrying out the slip casting to the soil body, can further consolidate the foundation soil layer, reduce or restrict the deformation of the soil body and subside. The tracking grouting can play a role in reinforcing and reinforcing stratum disturbance caused by excavation of the foundation pit 200, the tracking grouting can fill holes in a foundation soil layer and play a certain lifting role, and slight lifting of the building is realized through grouting of the inclined grouting holes so as to make up for differential settlement caused by excavation of the foundation pit 200, so that deformation and settlement of the existing building 100, particularly the civil insurance building group, are strictly controlled.

Compared with the prior art that a vertical curtain wall is formed between a building and a foundation pit through grouting to prevent the influence of unloading of soil layer excavation on the building in the process of foundation pit excavation, the grouting reinforcement method has the advantages that the grouting reinforcement is carried out on the lower portion of the existing building through the inclined grouting holes, and the grouting plan can be adjusted in real time according to deformation monitoring data of the foundation pit and the existing building by combining with the monitoring system to control deformation of the existing building and the foundation pit.

In some embodiments of the present disclosure, the support assembly comprises: and a plurality of supports arranged at intervals in the depth direction of the foundation pit 200. Wherein, the first support near the top of the foundation pit 200 is a concrete support; the second support to the Nth support are sequentially arranged below the first support at intervals, and the second support to the Nth support are all servo steel supports; wherein N is a positive integer greater than or equal to 2.

Compare with the local section of foundation ditch 200 adoption servo steel support, the foundation ditch supporting construction that this some embodiments of this disclosure provided adopts global servo's supporting component, namely, at the whole section of foundation ditch 200, except that first concrete supports 381, other supports all adopt servo steel support, can be in real time, accurate, adjust foundation ditch 200's support axial force intelligently, provide better, more stable support for foundation ditch 200 to realize the deformation of existing buildings 100 such as control ancient building crowd.

In some embodiments of the present disclosure, the foundation pit supporting structure further comprises: and a support axis force servo compensation system 370 connected to the second track support to the nth track support. The support axis force servo compensation system 370 is configured to: applying pre-applied axial force to the second support to the Nth support respectively; and (3) applying axial force to the second to Nth supports in a grading manner according to the construction progress, and/or applying axial force to the second to Nth supports according to the deformation condition of the foundation pit 200 and/or the existing building 100.

The support axial force servo compensation system 370 is a set of intelligent foundation pit 200 displacement control system composed of hardware equipment and software programs, is suitable for engineering projects with strict control requirements on deformation of a foundation pit supporting structure in the excavation process of the foundation pit 200, can perform real-time monitoring for 24 hours, automatically performs low-pressure servo and high-pressure automatic alarm, and provides comprehensive multiple safety guarantee for the foundation pit 200. Illustratively, the support axial force servo compensation system 370 may include a host 373, a numerically controlled pump station 372, and a plurality of support head assemblies 371, the plurality of support head assemblies 371 being disposed at one end of the plurality of servo steel supports in a one-to-one correspondence to control axial force application to the servo steel supports.

The host 373 is composed of a program control host and a display, and can perform data transmission with the field numerical control pump station 372, control the adjustment of the axial force value and generate a monitoring report. The numerical control pump station 372 is also called a control cabinet and comprises a series of mechanical and electronic components, and the core of the work of the numerical control pump station 372 comprises a PLC (programmable logic controller), a variable frequency motor, a hydraulic pump, a wireless communication module, a hydraulic valve component, a power supply component, an alternating current contactor, a cable, an oil pipe interface and the like. The data pump station is used as a middle link to connect the program control host with the support head assembly 371, and information is transmitted between the program control host and the support head assembly to realize measurement and control of the steel support axial force. And the support head assembly 371 is connected with the steel support and is arranged at a design designated position of a foundation pit supporting structure. It is connected with the numerical control pump station 372 through oil pipes and cables to work. The support head assembly 371 includes a jack therein for applying an axial force to the steel support.

The supporting axial force servo compensation system 370 can be connected with the monitoring system 390, and when the deformation condition of the existing building 100 or the foundation pit 200 is monitored to exceed the early warning value, the supporting axial force servo compensation system 370 can be adopted to intelligently adjust the output of the supporting axial force of the servo steel in real time so as to form good support for the foundation pit 200, reduce deformation and reduce the influence on the existing building 100.

A supporting axial force servo compensation system 370 is arranged in the whole range of the foundation pit, and can also be called as a construction global servo steel support, and the effect of the system on the safety control of the existing building or the foundation pit is obvious. Although the cost of the early investment of the global servo steel support is higher than that of the common steel support/local servo steel support, the hidden benefit generated by the global servo steel support is huge under the condition of ensuring the self safety of buildings and foundation pits. The foundation pit is globally servo-actuated, and the method has the advantages of strong operability, good deformation control effect, intelligent axial force adjustment, high automation degree and good integral stress of the underground continuous walls around the foundation pit, has small disturbance to surrounding buildings and can effectively control the deformation of the existing buildings and the foundation pit.

In some embodiments of the present disclosure, the foundation pit supporting structure further comprises: a monitoring system 390 coupled to the support shaft force servo compensation system 370. The monitoring system 390 is configured to monitor the deformation of the excavation 200 and the deformation of the existing structure 100 and transmit the monitored data to the support axis force servo compensation system 370. Wherein, the deformation condition of the existing building 100 includes: at least one of a subsidence condition, an inclination condition, a vibration condition, a horizontal displacement condition, and a crack condition of the existing building 100.

Illustratively, for existing buildings such as the civil insurance building group, the preset control values of settlement and horizontal deformation are 5mm, the preset control values of inclined deformation are 3 ‰, the preset value of vibration is 0.1mm/s, and the preset control value of cracks is 0.25 mm. The preset control value can better meet the strict requirements of the existing buildings such as the civil insurance building group and the like on construction disturbance. The deformation condition of the existing building 100 is monitored, and the deformation preset control value can be strictly controlled by combining the foundation pit supporting structure and the foundation pit construction method mentioned in some embodiments of the present disclosure, so that construction disturbance is reduced, and the safety and stability of the civil security building group are ensured.

In some embodiments of the present disclosure, along a direction in which the center of the foundation pit 200 points to the boundary of the foundation pit 200, the region outside the foundation pit 200 is sequentially divided into a first affected zone, a second affected zone, and a third affected zone. The shortest distance between the soil body at any position in the first affected area and the foundation pit 200 meets the condition that L is less than or equal to M; the shortest distance between the soil body at any position in the second affected area and the foundation pit 200 meets the condition that M is more than L and less than or equal to 2M; the shortest distance between the soil body at any position in the third affected area and the foundation pit 200 meets the condition that L is more than 2M; wherein L is the shortest distance between the soil outside the foundation pit 200 and the foundation pit 200; m is an influence range critical value of excavation of the foundation pit 200, M is 3H, and H is an average depth of the foundation pit 200. The monitoring system 390 includes a plurality of monitoring elements 392, the plurality of monitoring elements 392 disposed at the first, second, third, and outer edges of the foundation pit 200; wherein the arrangement density of the monitoring elements 392 decreases in the first, second and third influence zones in sequence.

For example, as shown in fig. 7, the monitoring system 390 may include a cloud service platform 391 as a controller, and monitor deformation of the existing building 100 and deformation of the foundation pit 200 through a detection component disposed at a monitoring point, and upload the detection result to the cloud service platform 391. Meanwhile, the cloud service platform 391 is further in communication connection with the supporting axial force servo compensation system 370, monitored data can be transmitted to the supporting axial force servo compensation system 370, and the supporting axial force servo compensation system 370 adjusts the axial force output by the servo steel support accordingly.

Taking the existing building 100 as a civil insurance building group as an example, the monitoring components 392 arranged at the monitoring points can be arranged at the first influence area, the second influence area, the third influence area and the outer edge of the foundation pit 200, and the closer the positions to the foundation pit 200 are, the larger the disturbance is, the denser the arrangement of the monitoring points is; the farther away from the foundation pit 200, the smaller the disturbance, and the sparser the arrangement of the monitoring points. Thus, the first zone of influence is arranged with a greater number of monitoring points than the second zone of influence. For example, in the first influence area, monitoring points are arranged every 10m along the outer wall of the civil insurance building group, and in the second influence area, monitoring points are arranged every 20m along the outer wall of the civil insurance building group. The monitoring points can be arranged on the wall of the building, the civil insurance structure (such as rockeries and mountain stones) or underwater according to the requirements of monitoring projects, such as the settlement monitoring points 393 and the crack monitoring points 394, so as to monitor the settlement condition, the inclination condition, the vibration condition, the horizontal displacement condition, the crack condition and the like of the civil insurance structure group during the excavation of the foundation pit 200. Monitoring points may also be disposed at the outer edge of the excavation 200, such as excavation deformation monitoring points 395, to monitor the deformation of the excavation 200.

In the monitoring process, the monitoring component 392 can be used for automatic monitoring, the monitoring component 392 can also be used for manual monitoring, or the monitoring is carried out in a mode of combining manual monitoring and automatic monitoring. For example, the settlement, inclination, horizontal displacement or crack condition of civil insurance buildings and structures is monitored manually. Also for example, automated monitoring of settlement, tilt and vibration of buildings and structures, as well as water level changes within shelters, is employed. For another example, the settlement and the inclination of the civil insurance buildings and structures are monitored in a manner of combining manual monitoring and automatic monitoring, so that the reliability of the measurement result is improved.

The monitoring component 392 includes instruments for monitoring the corresponding items, signal transmission devices, and the like. The instruments monitoring the respective items are for example: the hydrostatic level that can realize subsiding automatic monitoring can realize the wireless tilt sensor of the automatic monitoring of slope, can realize the vibration sensor of the automatic monitoring of vibration, and the fluviograph of the formula of putting into that can realize the automatic monitoring of water level monitors etc.. The signal transmission device may be a wired or wireless communication device. Automated collection and transmission of numbers of instances of deformation of an existing structure 100 or foundation pit 200 can be accomplished via the monitoring assembly 392.

In some embodiments of the disclosure, the excavation supporting structure further comprises: a plurality of stud piles 341 disposed in the foundation pit 200, and a plurality of lattice columns 342 into which the plurality of stud piles 341 are inserted in one-to-one correspondence.

The lattice column 342 is used as a supporting point of the inner support of the foundation pit 200, so that the deflection deformation of the inner support can be reduced, the bending resistance of the inner support is improved, and the stability of the foundation pit 200 is ensured. Illustratively, the lattice column 342 is formed by welding angle steel/channel steel and steel plates, is arranged near the middle position of two adjacent servo steel supports, and is arranged at intervals of 6-8 m along the length and width directions of the foundation pit 200, and the specific number of the lattice columns can be set according to the actual size of the foundation pit 200.

The bored pile may be used as the upright pile 341, and the lattice columns 342 are inserted into the bored pile in one-to-one correspondence to be welded to the main ribs in the bored pile. The stud 341 may serve as a foundation for the lattice column 342 and may serve to resist the bulging deformation of the bottom of the foundation pit.

In some embodiments of the present disclosure, the foundation pit support structure further comprises a plurality of dewatering wells; the plurality of dewatering wells include: at least one pit inner drainage well and at least one pit inner depressurization well which are arranged in the foundation pit 200, and at least one pit outer water level observation well and a recharging well which are arranged outside the underground continuous wall 310.

The dewatering well in the foundation pit 200 mainly comprises a dewatering well in the pit and a depressurization well in the pit. The pit drainage well is mainly used for draining the submerged water and the micro-pressure bearing water in the excavation range. The depressurization well in the pit is mainly used for reducing the confined water below the bottom 203 of the foundation pit to a safe water level. The dewatering well in the pit is arranged near the first concrete support 381 and is perpendicular to the plane of the first concrete support 381. The distance between the dewatering well and the first concrete support 381 is 50-100 cm. The central distance between every two dewatering wells is 10-15 m, and the number is determined according to the length and the width of the actual foundation pit 200. For example, for a soil layer area with high water content, the dewatering wells may be arranged near the first concrete supports 381, perpendicular to the plane of the first concrete supports 381, at a distance of 50cm or 60cm from the first concrete supports 381, and at a central distance of 10m or 11 m. For the area with low water content in the soil layer, the dewatering wells can be arranged near the first concrete supports 381 and perpendicular to the plane of the first concrete supports 381, the distance between the dewatering wells and the first concrete supports 381 is 90cm or 100cm, and the central distance between the dewatering wells is 15 m.

When the pressure reduction well in the pit is constructed, the anti-surge checking calculation is required according to the actually measured water head. Illustratively, the anti-surge condition may be checked according to a magnitude relationship between a self-weight pressure of soil between the bottom plate of the foundation pit 200 to the top plate of the confined aquifer and a jacking force of the confined water at the top plate of the confined aquifer. When the self-weight pressure of the soil is smaller than the jacking force of the confined water at the top plate of the confined water aquifer, the pressure needs to be reduced, so that the numerical value of the self-weight pressure of the soil is larger than or equal to the numerical value of the jacking force of the confined water at the top plate of the confined water aquifer, and the safety is calculated (no surging occurs).

The out-pit diving observation well and the out-pit confined water observation well are collectively called as an out-pit water level observation well and also serve as a recharging well. The out-pit confined water observation well is used for observing the change condition of the out-pit confined water level. The water level observation well and the recharge well outside the pit can be arranged 2-2.5 m away from the outer side of the underground continuous wall 310. And guiding precipitation operation and excavation construction according to the observation result of the observation well, the deformation of the surrounding civil insurance building group, the water level change in the civil insurance building group and the change condition of the foundation pit 200. It should be noted that the pit-outside recharging well cannot be disposed in a high-risk area such as a joint of the underground diaphragm wall 310, which is prone to water leakage. If the recharging well is arranged at the joint, water leakage is more likely to occur, and the air tightness and the effect of recharging are affected. When the water level of the water area of the existing building 100 is suddenly reduced and the existing building 100 is obviously settled, the recharging well can be started to carry out recharging in stages.

In addition, in the precipitation process, the precipitation construction process needs to be adjusted in time according to the monitoring data of the surface water level of the area of the existing building 100, and the influence on the surface water level safety of the area of the existing building 100 is avoided. When the water level rises obviously, the dewatering well in the pit is started, and dewatering is carried out in a staged and gradual dewatering mode. And when the water level is obviously reduced, starting the recharging well outside the pit, and recharging by adopting a staged gradual recharging mode. In addition, the deformation support of the foundation pit 200 needs to be strengthened, and the change situation of the axial force of the servo steel support is paid attention to in time.

In some embodiments of the present disclosure, the foundation pit supporting structure further includes a crown beam 350 disposed on the top surface of the foundation pit 200.

Some embodiments of the present disclosure also provide a foundation pit construction method, which is suitable for a foundation pit adjacent to an existing building, and the foundation pit 200 includes a first sub-foundation pit 201 adjacent to the existing building 100 and a second sub-foundation pit 202 distant from the existing building 100. As shown in FIG. 8, the construction method includes steps S1 to S4.

S1, a first sub underground diaphragm wall 311 is constructed around the side wall of the first sub foundation pit 201 of the foundation pit 200 to be excavated.

S2, the top of the first sub-foundation pit 201 is covered with a temporary overlay layer 330.

And S3, constructing a second sub underground continuous wall 312 around the side wall of the second sub foundation pit 202 of the foundation pit 200 to be excavated, wherein the first sub underground continuous wall 311 and the second sub underground continuous wall 312 enclose the underground continuous wall 310.

S4, a support member for supporting the foundation pit 200 is implemented in the foundation pit 200.

In some embodiments of the present disclosure, before the step S1, the construction method further includes S5: initial information collection is performed for the existing building 100 and the underground condition of the existing building 100.

The step S5 includes S51-S53.

And S51, according to the influence range of the excavation of the foundation pit 200, sequentially dividing the area outside the foundation pit 200 into a first influence area, a second influence area and a third influence area along the direction of pointing the center of the foundation pit 200 to the boundary of the foundation pit 200.

Wherein the shortest distance between the soil body at any position in the first affected area and the foundation pit 200 satisfies that L is less than or equal to M; the shortest distance between the soil body at any position in the second affected area and the foundation pit 200 meets the condition that M is more than L and less than or equal to 2M; the shortest distance between the soil body at any position in the third affected area and the foundation pit 200 meets the condition that L is more than 2M; l is the shortest distance between the soil outside the foundation pit 200 and the foundation pit 200; m is an influence range critical value of excavation of the foundation pit 200, M is 3H, and H is an average depth of the foundation pit 200.

And S52, detecting underground cavities and void disasters of the first and second affected areas. Wherein the first zone of influence is detected with a higher fineness than the second zone of influence.

S53, initial data of the existing building 100 is collected. The initial data includes: initial water level, initial elevation, initial damage condition, initial background vibration and initial crack.

Taking the existing building 100 as a civil insurance building group as an example, firstly, determining the critical value M of the excavation influence range of the foundation pit according to the excavation depth of the foundation pit 200 and a method of 3 times the excavation depth of the foundation pit 200. That is, M is 3H, and H is the average depth of the foundation pit 200. According to the critical value M of the excavation influence range, the area outside the foundation pit 200 is divided into a plurality of foundation pit 200 influence range partitions, and a detection partition and a monitoring partition of a file protection area are established, and specific description is shown in Table 1. Fine detection is carried out underground in the first influence area, common detection is carried out underground in the second influence area, and detection is not carried out in the third influence area. The equipment used for detection is, for example, a multi-frequency ground penetrating radar.

Illustratively, for fine detection, a plurality of measuring lines are arranged underground in a first influence area, for example, one measuring line is arranged at an interval of 0.5-1 m for encryption detection, the total length of the measuring lines is longer, the detection range is wider and more comprehensive, and the omission probability is low. And (3) commonly detecting an area which is convenient for arranging the measuring lines in the second affected area, such as a pavement of a sidewalk road, arranging 1 or 2 measuring lines, wherein the total length of the measuring lines is shorter and the coverage area is relatively smaller. Whether the detection is fine detection or common detection is to find out whether underground cavities and empty disasters exist in the affected area, namely whether underground disease bodies exist. The development of the detection work is completed before the excavation of the foundation pit 200.

And then, acquiring initial data of buildings and cultural relics in the cultural relic area by adopting three-dimensional scanning, building/structure identification and other modes and combining the detection data, and classifying objects and refining control indexes. The initial data collected mainly includes: initial water level, initial elevation, initial damage condition, initial background vibration, initial crack and the like.

According to the acquired data result, the cultural protection buildings and cultural relics with poor initial conditions or great damage are classified into one category, the cultural protection buildings and the cultural relics need to be encrypted and monitored in a key mode, and active prevention and control are needed before construction under necessary conditions. And the construction method also belongs to the category of the cultural relics and the cultural relics with better initial conditions, and is used for normal monitoring during construction.

The indexes monitored during construction are control indexes, and the method mainly comprises the following steps: inclination of the building, cracks, settlement, horizontal displacement, vibration, and changes in water level within the building.

TABLE 1

Region partitioning	Influence range of foundation pit excavation	Detecting a condition	Monitoring conditions
				First area of influence	L≤M	Encrypted detection	Enhanced monitoring
Second area of influence	M＜L≤2M	General detection	Routine monitoring
				Third zone of influence	L＞2M	Do not make detection	Local monitoring

In some embodiments of the present disclosure, before the step S1, the construction method further includes S6: a monitoring system 390 is provided to monitor the deformation of the foundation pit 200 and the existing structure 100 and transmit the monitored data to the support axis force servo compensation system 370. Wherein, the deformation condition of the existing building 100 includes: at least one of a subsidence condition, an inclination condition, a vibration condition, a horizontal displacement condition, and a crack condition of the existing building 100. The monitoring system 390 includes a plurality of monitoring elements 392, the plurality of monitoring elements 392 being disposed at the first, second, third, and outer edges of the foundation pit 200, wherein the density of the disposition of the monitoring elements 392 decreases in sequence in the first, second, and third areas of influence.

The monitoring system 390 may include a cloud service platform 391 as a controller, and monitor deformation of the existing building 100 and deformation of the foundation pit 200 through a detection component disposed at a monitoring point, and upload a detection result to the cloud service platform 391. Meanwhile, the cloud service platform 391 is also in communication connection with the supporting axial force servo compensation system 370, and can transmit monitored data to the supporting axial force servo compensation system 370, and the supporting axial force servo compensation system 370 adjusts the axial force output by the servo steel support accordingly.

Taking the existing building 100 as a civil insurance building group as an example, the monitoring components 392 arranged at the monitoring points can be arranged at the first influence area, the second influence area, the third influence area and the outer edge of the foundation pit 200, and the closer the positions to the foundation pit 200 are, the larger the disturbance is, the denser the arrangement of the monitoring points is; the farther away from the foundation pit 200, the smaller the disturbance, and the sparser the arrangement of the monitoring points. Thus, the first zone of influence is arranged with a greater number of monitoring points than the second zone of influence. For example, in the first influence area, monitoring points are arranged every 10m along the outer wall of the civil insurance building group, and in the second influence area, monitoring points are arranged every 20m along the outer wall of the civil insurance building group. The monitoring points can be arranged on the wall of a building, a civil insurance structure (such as rockery and peak stone) or underwater according to the requirements of monitoring projects, so as to monitor the settlement condition, the inclination condition, the vibration condition, the horizontal displacement condition, the crack condition and the like of the civil insurance building group during the excavation of the foundation pit 200. The monitoring points may also be arranged at the outer edge of the foundation pit 200 to monitor the deformation of the foundation pit 200.

In some embodiments of the present disclosure, before the step S1, the construction method further includes S7: for the existing building 100 within the reinforcing range, embedding sleeve valve grouting pipes 400 2 m-3 m below the foundation of the existing building 100; the reinforcement range comprises a range which is located outside the side wall of the foundation pit and has a horizontal distance with the side wall of the foundation pit smaller than or equal to 0.7H, wherein H is the average excavation depth of the foundation pit. After step S2, the construction method further includes S8: according to the deformation condition of the existing building 100, the stratum under the existing building 100 is subjected to tracking grouting by using the sleeve valve grouting pipe 400.

The sleeve valve grouting pipe 400 is pre-embedded 2 m-3 m below the foundation of the existing building 100, specifically, a plurality of inclined grouting holes are drilled at one side or multiple sides of the existing building 100, one end of each grouting hole is located on the ground, the other end of each grouting hole is located underground, and the grouting holes are located 2 m-3 m below the foundation of the existing building 100. And sleeve valve grouting pipes 400 are arranged in the inclined grouting holes to realize grouting at 2-3 m below the foundation of the existing building 100 to form a soil body reinforcing structure 360.

In some embodiments of the present disclosure, before the step S1, the construction method further includes S9: and (3) changing pipelines influencing the construction of the underground continuous wall 310, completing enclosure sealing and breaking the ground or the road surface.

For example, during the construction process of breaking the ground or the road surface, a non-impact crusher such as a road milling machine or a hydraulic pick may be used for crushing, and the influence of the construction vibration on the surrounding existing building 100 may be reduced from the source in cooperation with the manual dismantling manner.

In some embodiments of the present disclosure, after the step S1, the construction method further includes S10 to S11.

S10, a first sub-crown beam 351 is formed on the top surface of the first sub-foundation pit 201.

S11, a plurality of vertical piles 341 are formed in the foundation pit 200, and a plurality of lattice columns 342 into which the plurality of vertical piles 341 are inserted in a one-to-one correspondence.

After step S3, the construction method further includes S12: and a second sub-crown beam 352 is formed on the top surface of the second sub-foundation pit 202.

Since the half-covered and excavated temporary covering layer 330 on the first sub-foundation pit 201 is first applied to relieve traffic pressure, the first sub-underground continuous wall 311 and the first sub-crown beam 351 may be first applied, and the second sub-crown beam 352 may be applied after the application of the temporary covering layer 330 is completed.

In some embodiments of the present disclosure, the underground continuous wall 310 comprises a plurality of trough sections 313, wherein each trough section 313 comprises a plurality of wall webs 314, and the plurality of wall webs 314 in any trough section 313 are implemented in a "three-by-one" trough-forming sequence.

The grooving sequence of three-step and one-step separation is shown in fig. 9, and fig. 9 shows the excavating sequence of one groove section 313, that is, each groove section 313 is excavated in four steps of I sequence, II sequence, III sequence and IV sequence, the wall width of the I sequence is excavated first, then the wall width of the II sequence is excavated by skipping the wall width of the III sequence, then the wall width of the III sequence is excavated, and finally the wall width of the IV sequence is excavated. In the excavation process of the foundation pit 200, a grab bucket type grooving process can be adopted, and the length of each groove section 313 is not more than 6 m.

In the construction process of the underground continuous wall 310, the grooving sequence of three-by-one is adopted for construction, so that the disturbance on the surrounding soil body when the underground continuous wall 310 is grooved can be reduced, and particularly for the construction of the first sub-continuous wall, the grooving sequence of three-by-one can be adopted, so that the excavation disturbance and the construction vibration of the unit groove section 313 can be controlled more strictly.

In some embodiments of the present disclosure, for the underground continuous wall 310 having the shortest distance from the existing building 100 of less than 10m to 12m, the high pressure jet grouting method pile 320 is applied at the joint between each adjacent two wall panels 314.

In some embodiments of the present disclosure, step S4 includes S41-S42.

And S41, constructing a first support at a position close to the top of the foundation pit 200. The first support is a concrete support.

And S42, sequentially constructing a second support to an Nth support from top to bottom along the depth direction of the foundation pit 200. The second support to the Nth support are all servo steel supports, and N is a positive integer greater than or equal to 2.

In some embodiments of the present disclosure, step S42 includes implementing the second servo steel support 382 through the nth servo steel support. The method specifically comprises the following steps: s421 to S422.

S421, excavating the foundation pit 200 by adopting a construction mode of subsection, layering and substep, and installing the servo steel support when the foundation pit is excavated to the erection elevation of any one of the second servo steel support to the Nth servo steel support.

In the process of subsection layering step-by-step excavation, the length of each subsection can be 15-20 m, the layering thickness can be 2.5-3 m, the length of each step can be 5-6 m, and the longitudinal gradient ratio in the foundation pit 200 is smaller than 1: 2.5.

S422, the support axial force servo compensation system 370 connected with the second to Nth servo steel supports is adopted to apply pre-applied axial force to the second to Nth servo steel supports respectively, and axial force is applied to the second to Nth supports according to the deformation condition of the foundation pit 200 and/or the existing building 100.

In some embodiments of the present disclosure, for the p-th track servo steel support and the q-th track servo steel support of the second track servo steel support to the N-th track servo steel support:

the pre-applied axial force applied to the p-th servo steel support is 100-10 x (N-p) ]%, which is the designed axial force value;

the pre-applied axial force applied to the q-th servo steel support is [100-10 x (N-q) ] percent of the designed axial force value;

and (3) applying axial force to the second to the Nth servo steel supports in a grading manner, wherein the axial force comprises the following steps: when the distance between the support frame and the qth servo steel support is excavated, or the distance between the support frame and the qth servo steel support is excavated between the qth servo steel support and the qth servo steel support, the deformation rate of the foundation pit 200 and/or the existing building 100 reaches 75-80% of the preset control rate, and then axial forces with the designed axial force value of 10% -15% are respectively applied to the qth servo steel support until the axial force value of each servo steel support is added to the designed axial force value;

wherein p is more than or equal to 2 and q is more than or equal to q and less than 10, and both p and q are positive integers.

Each servo steel support comprises a plurality of servo steel supports, one end of each servo steel support is a fixed end, the other end of each servo steel support is a servo end, and the servo end is connected with a support head assembly 371 supporting the axial force servo compensation system 370. Illustratively, each servo steel support is paved with 20 servo steel supports, including 12 servo straight steel supports and 8 servo inclined steel supports. Servo oblique steel shotcrete all sets up the corner at foundation ditch 200, and the underground continuous wall 310 of corner takes place stress concentration easily, and in the foundation ditch 200 excavation process, the underground continuous wall 310 of corner takes place deformation fracture easily, influences foundation ditch 200 stability and security. The construction control difficulty is large at the position, so servo oblique steel supports can be arranged at the corners to increase the stability of the foundation pit 200. In addition, a steel plate corner brace can be arranged at the corner to assist in supporting the corner, and the stability of the foundation pit 200 is further improved.

After each servo steel support frame is erected, pre-applied axial force needs to be applied in time, and the axial force is applied to a designed axial force value in a grading mode along with excavation. Illustratively, seven supports are erected in the foundation pit 200, wherein the first support is a concrete support, and the second support to the seventh support are servo steel supports. And (5) waiting for excavating to the erection elevation of the servo steel support, and timely installing a second servo steel support to a seventh servo steel support based on the support shaft force servo compensation system 370. In the construction process, when a second servo steel support is erected, applying a pre-applied axial force to the second servo steel support which is 50% of a designed axial force value; when the height of the third servo steel support is excavated or the height between the second servo steel support and the third servo steel support is excavated and the deformation rate of the foundation pit 200 and/or the existing building 100 reaches 75-80% of the preset control rate, applying an axial force with a designed axial force value of 15% to the second servo steel support; after the third servo steel support is erected, applying pre-applied axial force to the third servo steel support to be 60% of the designed axial force value; when the height of the fourth servo steel support is excavated or the height between the third servo steel support and the fourth servo steel support is excavated and the deformation rate of the foundation pit 200 and/or the existing building 100 reaches 75-80% of the preset control rate, applying an axial force with a designed axial force value of 15% to the second servo steel support and applying an axial force with a designed axial force value of 15% to the third servo steel support; after the fourth servo steel support is erected, applying pre-applied axial force to the fourth servo steel support to be 70% of the designed axial force; when the height of the fifth servo steel support is excavated or the height between the fourth servo steel support and the fifth servo steel support is excavated and the deformation rate of the foundation pit 200 and/or the existing building 100 reaches 75-80% of the preset control rate, applying an axial force with a designed axial force value of 15% to the second servo steel support, applying an axial force with a designed axial force value of 15% to the third servo steel support and applying an axial force with a designed axial force value of 15% to the fourth servo steel support; after the fifth servo steel support is erected, applying a pre-applied axial force to the fifth servo steel support to be 80% of the designed axial force value; when the height of the sixth servo steel support is excavated or the height between the fifth servo steel support and the sixth servo steel support is excavated, and the deformation rate of the foundation pit 200 and/or the existing building 100 reaches 75-80% of the preset control rate, the axial force of the second servo steel support is fully added to the designed axial force value, the axial force with the designed axial force value of 15% is applied to the third servo steel support, the axial force of the fourth servo steel support is fully added to the designed axial force value, and the axial force with the designed axial force value of 15% is applied to the fifth servo steel support; after the sixth servo steel support is erected, applying a pre-applied axial force to the sixth servo steel support which is 90% of the designed axial force value; when the height of the seventh servo steel support is excavated or the height between the sixth servo steel support and the seventh servo steel support is excavated and the deformation rate of the foundation pit 200 and/or the existing building 100 reaches 75-80% of the preset control rate, the axial force of the third servo steel support is fully added to the designed axial force value and the axial force of the fifth servo steel support is fully added to the designed axial force value; after the seventh steel support is erected, the axial force of the seventh servo steel support is directly added to the designed axial force value (100%).

In some embodiments of the present disclosure, after the support assembly for supporting the foundation pit 200 is implemented within the foundation pit 200, the construction method further includes S12: and constructing the main structure in the foundation pit 200 in sections according to the sequence from bottom to top.

Taking the case of constructing a station to be built in the foundation pit 200 as an example, the foundation pit 200 to be built is excavated and constructed to the bottom of the pit, after a soil layer is leveled, a bottom plate cushion layer is sequentially poured from bottom to top, a waterproof layer and a fine aggregate concrete protective layer are laid, the main body structures of the station, such as a bottom plate, a lower side wall, an upper side wall, a top plate and the like of the underground station, are constructed, and the support system is sequentially removed while the main body structures are constructed according to the construction sequence.

Wherein, when the bottom plate structure is constructed, the dredging well needs to be blocked and the drain hole needs to be arranged. The weep hole is arranged at the bottom plate position of the foundation pit 200. After the foundation pit 200 is excavated to the bottom of the pit, when a bottom plate of a main structure of a subway station is constructed, a drain hole is arranged at a well point pipe (dewatering well). That is, the existing partial drainage wells in the pit are converted into the drainage holes of the bottom plate, and the radius of each drainage hole is 7-8 m. The weep hole keeps the operation, can guarantee foundation ditch 200 bottom plate structure's safety to improve the whole anti stability of floating of whole foundation ditch 200 structure.

Taking a subway station constructed in three layers as an example, the construction sequence is as follows: bottom plate cushion → bottom plate structure → sixth and seventh servo steel supports → negative three-layer side wall (lower side wall) and laminate structure → fourth and fifth servo steel supports → negative two-layer side wall (middle side wall) and laminate structure → second and third servo steel supports → negative one-layer side wall (upper side wall) and top plate structure → top plate waterproof layer is laid → capping beam 500 is poured → first concrete support 381, crown beam 350, temporary capping layer 330 and lattice column 342 are demolded → earth is backfilled to design ground elevation → secondary structure is constructed and the drain hole is closed.

The secondary structure is an auxiliary structure related to the station, such as a station platform plate, a partition wall, a lining wall and the like. In addition, the capping beam 500 arranged on the station roof can form an anti-floating structure with the underground continuous wall 310, and the underground continuous wall 310 at the position of the capping beam 500 needs to be embedded with a steel bar connector. The reinforcing steel bar connector is arranged on the underground continuous wall 310 at the position of the capping beam 500, so that the capping beam 500 is connected with the underground continuous wall 310 through the connector, and the capping beam 500 and the underground continuous wall 310 form an integral anti-floating structure to resist floating deformation of a station structure caused by subsequent water level change or other factors.

According to the supporting structure of the foundation pit 200 adjacent to the existing building 100 and the foundation pit construction method, aiming at the existing building 100 needing strict control of construction disturbance such as a cultural relic protection building group, construction is carried out by adopting a half-cover-excavation forward construction method, and a temporary covering layer 330 is constructed on the side of the adjacent existing building 100 to form local cover excavation, so that smooth traffic near the existing building 100 is ensured, the traffic problem is solved, disturbance and influence of excavation on the existing building 100 near the foundation pit 200 are reduced, and the construction period is greatly shortened.

Before the excavation construction of the foundation pit 200, initial information acquisition is carried out on the underground condition of the existing building 100 (such as an ancient building group in a literary and protective area), an intelligent monitoring system 390 is arranged inside and outside the foundation pit 200, and by combining the embedded sleeve valve grouting pipe 400 and the support axial force servo compensation system 370, real-time tracking grouting according to monitoring data can be realized, the foundation soil layer is reinforced in time, axial force is exerted on the foundation pit 200 in time through a servo steel support, and the deformation of the existing building 100 and the foundation pit 200 is controlled.

The joints of the underground continuous walls 310 are sealed by adopting the high-pressure jet grouting construction method piles 320, the surface water level change and the deformation of surrounding soil layers and the existing building 100 in the dewatering process of the foundation pit 200 are strictly monitored, and the surface water level safety of the area where the existing building 100 is located can be ensured by combining the construction of dewatering wells.

The supporting axial force servo compensation system 370 is adopted to apply axial force to the servo steel support in a grading manner, and the method has the advantages of time saving, labor saving, real-time feedback of the change of the axial force, timely adjustment of the magnitude of the axial force and the like, so that the deformation of the foundation pit 200 can be accurately controlled. The supporting axial force servo compensation system 370 has the advantages of high control precision, high automation degree, high safety coefficient, good overall control and the like, and can make up the defects of uneven stress and poor displacement control effect of the traditional servo method (a steel support servo system is erected locally in a foundation pit), so that the safety and stability of the foundation pit 200 and the surrounding existing building 100 are further ensured.

The foundation pit construction method of the present disclosure will be described in detail below by taking a suzhou rail transit 6 # line 5 marked clumsical garden station foundation pit 210 as an example.

A foundation pit 210 of a poor political station, as marked by the number 6 line 5 of the suzhou rail transit, of the drawing, excavates the suzhou museum 110, the poor political garden 120 and the tai-tian kingdom of the national key cultural relic protection unit. The length of the foundation pit 210 of the political garden station is 246.9m, the width is 20.7m, and the average excavation depth of the standard section is 17.1 m. The station is constructed by adopting a half-cover-digging method, is a subway station at two underground floors, has the minimum horizontal distance of about 4.22m from a Suzhou museum 110, about 10.6m from a political garden 120 and about 107m from the peace Tianguo kingdom, and has a relative position relationship plan as shown in FIG. 10. In view of the importance and the particularity of ancient building groups and cultural relics in the cultural relic protection area, in the construction process of the foundation pit 210 of the clumsiness and government station, the influences of construction vibration, excavation disturbance and underground water level change on the cultural and protection building groups need to be strictly controlled so as to ensure the safety of the cultural and protection building groups.

The method for constructing the foundation pit strictly controls the deformation of the adjacent cultural relic protection ancient building group, and comprises the following specific steps:

according to the fact that the average excavation depth of the standard section of the foundation pit 210 of the clumsiness garden station is 17.1M, and considering that the excavation depth of the end well of the foundation pit is larger than the average depth of the standard section by about 2M, in the project, 57.3M is rounded by (17.1+2) × 3 ═ 57.3M, and the critical value M of the excavation influence range of the foundation pit is determined to be 58M.

As can be seen from table 1 and the above description of relative positions, the suzhou museum 110 and the poor government 120 both belong to the first affected area, and the monitoring area is a strengthened monitoring area, i.e. the monitoring points in the area need to be encrypted; the peaceful Tianguo loyalty dynasty belongs to a second influence area, the monitoring subarea belongs to a conventional monitoring area, namely, monitoring points in the area do not need to be encrypted and can be monitored conventionally.

Before construction, survey all the initial states of ancient buildings, rockeries and the like in museums, clumsiness political parks 120 and loyalty mansion and acquire initial information, and the method mainly comprises the following steps: initial water level, initial elevation, initial damage condition, initial background vibration, initial crack and the like. And further refining key protection buildings according to the influence subareas and the initial survey results, and performing key monitoring and protection control.

For ancient buildings of the Suzhou museum 110 and the poor political garden 120 in the first influence area, the automatic monitoring is mainly used, and the manual monitoring is used as an auxiliary; the ancient buildings located in the second influence area and faithfully in the royal house are monitored manually or automatically according to the protection level of the ancient buildings. Wherein, the water level in the district is protected to whole literary composition and vibration monitoring all adopts automatic monitoring to go on, and the monitoring of subsiding, slope, horizontal displacement and crack adopts artifical and the mode that the automation combined together to go on.

According to the excavation depth of the foundation pit, the excavation depth of the foundation pit is 0.7 time, the excavation depth of the foundation pit is about 12.0m, the sleeve valve grouting pipe 400 is embedded below the historic building foundation of the document protection area within the range of 12.0m outside the foundation pit, and the inclination angle of the sleeve valve pipe is 65 degrees. Based on the above, sleeve valve grouting pipes 400 are pre-embedded under the foundations of some ancient buildings in the suzhou museum 110 and the clumsical garden 120 and are inserted into the foundations 3m below, the row pitch and the pitch of the grouting holes are both 1.5m, and the hole diameter is 100 mm. In the subsequent excavation process of the foundation pit, tracking grouting is carried out to reinforce the foundation soil layer of the ancient building based on the real-time monitoring data of the ancient building group in the civil insurance area.

And constructing surrounding barriers around the foundation pit 210 of the clumsiness garden station, and completing pipeline relocation operation around a construction area. In combination with the manual demolition method, the ground was broken using a non-impact XM200K type milling machine.

Underground continuous walls 310 near suzhou museum 110 and the poor political garden 120, that is, underground continuous walls 310 having a shortest distance of less than 10m from the civil engineering structure, are sealed by wall joints using high pressure jet grouting method piles 320(MJS), and an enlarged schematic view of the construction is shown in fig. 6. In total, 36 high-pressure rotary spraying method piles 320 are constructed on site, the diameter of the high-pressure rotary spraying method pile 320 is 2m, the range is 120 degrees, P42.5 common Portland cement is adopted, the cement mixing amount is 40 percent, and the water cement ratio is 1: 1. Then, a first sub-crown beam 351 and a 1000 cast-in-place pile are sequentially constructed as a column pile 341 (pile length 35m), a 550 × 550 steel lattice column 342 and a temporary paving layer 330 of the road surface in the first sub-foundation pit 201 near the side of the suzhou museum 110 and the clumsical garden 120, wherein the width of the temporary paving layer 330 is 6.3m, and the thickness of the temporary paving layer is 300 mm.

And (3) continuously constructing the residual underground continuous wall 310 around the foundation pit and pouring a second sub-crown beam 352, wherein the thickness of the underground continuous wall 310 of the end well is 1000mm, and the thickness of other underground continuous walls 310 is 800 mm. And then the construction of the first concrete support 381 of the whole foundation pit is completed.

A micro confined water layer exists in a foundation pit 210 of a clumsiness garden station, a confined water layer 600 exists in a stratum below the pit bottom, the micro confined water layer can be torn through during excavation of the foundation pit, and meanwhile, the underground continuous wall 310 made of concrete is applied to a waterproof curtain of the foundation pit to partition micro confined water. The lower part of the underground continuous wall 310 extends into and enters the impervious layer 3m below the pit bottom, so that the inside of the pit adopts a dewatering well to carry out precipitation on micro-pressure bearing water. According to the geological survey data, the minimum confined water head of a confined water layer below the pit bottom is 4.46m, so that the buried depth of the confined water head needs to be effectively controlled in the excavation process, and the inrush accident is prevented. The anti-inrush condition of the foundation pit bottom plate is checked before the site excavation, namely,

wherein Ps is the pressure of the soil covering from the pit bottom to the top of the aquifer, P_wBearing water jacking force for bearing the position of the top plate of the water-bearing layer, F_sFor safety factor, Fs was taken to be 1.1.

According to the method, the pressure reduction and precipitation are needed in the foundation pit to reduce the water level to the safe water level, and the change of the water level inside and outside the pit during the precipitation is monitored in real time according to the observation wells inside and outside the pit, so that the adverse effect of the precipitation on the surrounding ancient building groups is reduced.

The foundation pit 210 of the clumsiness garden station is constructed by a half-cover excavation sequential method, and is constructed in a segmented, layered and block-divided mode in order to fully consider the space-time effect of foundation pit excavation. The excavation of the foundation pit 210 of the clumsiness garden station is totally divided into 12 sections, the length of each section is about 20m, the length of each step in each section is 6m, and the thickness of each step in each step is 3 m. After excavation is carried out to the design height each time, the servo steel supports are erected in time in sequence, prestress is applied, the mechanical lock is locked, and the axial force is increased to the design value in a grading mode in sequence along with excavation.

For example, when the second servo steel support 382 is erected, the pre-applied axial force applied to the second servo steel support 382 is 70% of the designed axial force value; when the height of a third servo steel support 383 is excavated or the height between a second servo steel support 382 and the third servo steel support 383 is excavated and the deformation rate of a foundation pit and/or a civil engineering and insurance building group reaches 75-80% of a preset control rate, applying an axial force with a design axial force value of 15% to the second servo steel support 382; after the third servo steel support 383 is erected, applying a pre-applied axial force to the third servo steel support 383, wherein the pre-applied axial force is 80% of the designed axial force value; when the height of the fourth servo steel support 384 is excavated, or when the height between the third servo steel support 383 and the fourth servo steel support 384 is excavated and the deformation rate of a foundation pit and/or a civil engineering and insurance building group reaches 75-80% of a preset control rate, applying an axial force with a design axial force value of 15% to the second servo steel support 382 (at the moment, the axial force of the second servo steel support 382 is fully added to the design axial force value), and applying an axial force with a design axial force value of 15% to the third servo steel support 383; after the fourth servo steel support 384 is erected, applying a pre-applied axial force to the fourth servo steel support 384 to be 90% of the designed axial force value; when the height of the fifth servo steel support 385 is excavated, or the height between the fourth servo steel support 384 and the fifth servo steel support 385 is excavated and the deformation rate of the foundation pit and/or the civil engineering and insurance building group reaches 75-80% of the preset control rate, the axial force of the third servo steel support 383 is filled to the designed axial force value, and the axial force of the fourth servo steel support 384 is filled to the designed axial force value; after the fifth servo steel support 385 is erected, the design axial force value (100%) is directly added to the fifth servo steel support 385.

In the inner support system of the whole foundation pit, except for the first support, the other supports (the second support, the third support, the fourth support and the fifth support) are all servo steel supports, so that a foundation pit safety control system integrating 24h axial force real-time monitoring, automatic compensation and intelligent early warning all day is formed systematically, and the influence of foundation pit excavation on surrounding soil layers and cultural and ancient conservation building groups is controlled to the maximum extent. In addition, the supporting axial force servo compensation system 370 is combined with the monitoring system 390, and the two systems perform real-time information feedback mutually, so that the safety of the civil insurance building group is further ensured.

And (5) after the foundation pit is excavated to the substrate, leveling the bottom soil layer. The main construction effect profile when the foundation pit is excavated to the basement is shown in fig. 11. Then, a main structure of a clumsiness garden station is constructed, and a specific step sequence diagram of the construction is shown in fig. 12 to 18, and the specific steps are as follows:

constructing a bottom plate cushion layer, a waterproof layer and a protective layer, and constructing a bottom plate structure (figure 12);

removing the fourth servo steel support 384 and the fifth servo steel support 385 according to design requirements (FIG. 13);

side walls and a middle plate of a second layer of the station negative are upwards constructed to the bottom of a third servo steel support 383 (fig. 14);

the second servo steel support 382 and the third servo steel support 383 are removed according to the design requirement (figure 15);

side walls and a top plate (figure 16) are upwards constructed as a station negative layer;

laying a roof waterproof layer and pouring a capping beam 500 (fig. 17);

and (3) removing the first concrete support 381, the crown beam 350, the lattice column 342 and the temporary paving layer 330, and backfilling and covering soil to the designed ground elevation (figure 18).

And finally, constructing secondary structures of the station, such as a station bedplate, a partition wall, an inner lining wall and the like, and closing the drainage holes.

Figure 19 shows a graph comparing the displacement of the diaphragm wall at the first monitoring point 396 of the underground diaphragm wall of the excavation. Lines with different marks respectively show an underground diaphragm wall displacement simulation result of the foundation pit construction method of the embodiment of the clumsiness garden station, an underground diaphragm wall displacement actual measurement result of the foundation pit construction method of the embodiment of the clumsiness garden station, an underground diaphragm wall displacement simulation result based on the construction object of the disclosure and adopting only global servo support and half cover excavation, and an underground diaphragm wall displacement simulation result based on the construction object of the disclosure and adopting only global servo support, half cover excavation and tracking grouting.

As can be seen in fig. 19: the numerical simulation is basically consistent with the displacement of the underground continuous wall of the clumsiness garden station obtained by field monitoring, and the feasibility of the numerical simulation is verified. The maximum displacement obtained by numerical simulation is 9.6mm, and the maximum displacement obtained by field actual measurement is 11.0 mm. The maximum displacement obtained by the simulation result of the displacement of the underground diaphragm wall only adopting the global servo support based on the construction object disclosed by the disclosure is 29.65mm, the maximum displacement obtained by the simulation result of the displacement of the underground diaphragm wall only adopting the global servo support plus the half-covered excavation based on the construction object disclosed by the disclosure is 18.72mm, and the maximum displacement obtained by the displacement simulation result of the underground diaphragm wall only adopting the global servo support plus the half-covered excavation plus the tracking grouting based on the construction object disclosed by the disclosure is 14.81 mm.

Fig. 20 shows a vertical displacement comparison of the warranty building at the second monitoring point 397 of the warranty building. Lines with different marks respectively show a vertical displacement simulation result of the literary composition insurance building of the embodiment of the clumsiness garden station, a vertical displacement actual measurement result of the literary composition insurance building of the embodiment of the clumsiness garden station, a vertical displacement simulation result of the literary composition insurance building only adopting global servo support based on the construction object of the disclosure, a vertical displacement simulation result of the literary composition insurance building only adopting global servo support + half cover excavation based on the construction object of the disclosure, and a vertical displacement simulation result of the literary composition insurance building only adopting global servo support + half cover excavation + tracking grouting based on the construction object of the disclosure.

As can be seen in fig. 20: the vertical displacement of the civil insurance building obtained by numerical simulation and field monitoring is basically consistent, and the feasibility of the numerical simulation is verified. The maximum displacement obtained by numerical simulation is 3.92mm, the maximum displacement obtained by field actual measurement is 4.02mm, and both the maximum displacement and the field actual measurement are smaller than a preset control value of 5 mm. The maximum displacement obtained by the simulation result of the displacement of the underground diaphragm wall only adopting the global servo support based on the construction object disclosed by the disclosure is 14.70mm, the maximum displacement obtained by the simulation result of the displacement of the underground diaphragm wall only adopting the global servo support and the half cover excavation based on the construction object disclosed by the disclosure is 9.821mm, and the maximum displacement obtained by the simulation result of the displacement of the underground diaphragm wall only adopting the global servo support, the half cover excavation and the tracking grouting based on the construction object disclosed by the disclosure is 8.018 mm.

As can be seen from fig. 19 and 20, in the foundation pit construction method provided by the present disclosure, multiple measures are combined, and the synergistic effect between the measures can maintain the deformation of the foundation pit and the existing building within a very small range, and particularly, for the civil insurance building group, the deformation requirement is very strict, and the foundation pit construction method of the present disclosure can achieve the strict requirements that the preset control value of the settlement and the horizontal deformation is 5mm, the preset control value of the inclined deformation is 3 permillage, the preset value of the vibration is 0.1mm/s, and the preset control value of the crack is 0.25 mm.

In the description herein, reference to the description of the terms "one embodiment/mode," "some embodiments/modes," "example," "specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment/mode or example is included in at least one embodiment/mode or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to be the same embodiment/mode or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments/modes or examples. Furthermore, the various embodiments/aspects or examples and features of the various embodiments/aspects or examples described in this specification can be combined and combined by one skilled in the art without conflicting therewith.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present disclosure, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise. "and/or" is simply an association that describes an associated object, meaning three relationships, e.g., A and/or B, expressed as: a exists alone, A and B exist simultaneously, and B exists alone. The terms "upper", "lower", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present disclosure. Meanwhile, in the description of the present disclosure, unless otherwise explicitly specified or limited, the terms "connected" and "connected" should be interpreted broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; the connection can be mechanical connection or electrical connection; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the present disclosure can be understood as a specific case by a person of ordinary skill in the art.

It will be understood by those skilled in the art that the foregoing embodiments are merely for clarity of illustration of the disclosure and are not intended to limit the scope of the disclosure. Other variations or modifications may occur to those skilled in the art, based on the foregoing disclosure, and are still within the scope of the present disclosure.

Claims

1. The utility model provides a foundation ditch supporting construction, is applicable to the foundation ditch of neighbouring existing building, a serial communication port, the foundation ditch includes the first sub-foundation ditch that is close to existing building and keeps away from the second sub-foundation ditch of existing building, foundation ditch supporting construction includes:

the underground continuous wall is arranged around the side wall of the foundation pit;

the supporting component is arranged in the foundation pit and used for supporting the foundation pit; and the number of the first and second groups,

and the temporary paving layer covers the top of the first sub foundation pit.

2. The excavation supporting structure of claim 1, wherein the underground continuous wall comprises a plurality of trough sections, each trough section comprising a plurality of wall panels;

the foundation pit supporting structure further comprises: the high-pressure rotary spraying construction method comprises a plurality of high-pressure rotary spraying construction method piles, wherein the high-pressure rotary spraying construction method piles are arranged at an underground continuous wall with the shortest distance of 10-12 m to an existing building, and one high-pressure rotary spraying construction method pile is correspondingly arranged at a joint between every two adjacent wall panels.

3. A foundation pit supporting structure according to claim 1, wherein for an existing building within a reinforcing range, a soil reinforcing structure is provided below the existing building; the soil body reinforcing structure is positioned 2 m-3 m below the foundation of the existing building; the reinforcement range comprises a range which is located outside the side wall of the foundation pit and has a horizontal distance with the side wall of the foundation pit smaller than or equal to 0.7H, wherein H is the average excavation depth of the foundation pit.

4. The excavation supporting structure of claim 1, wherein the support assembly comprises: a plurality of supports are arranged at intervals along the depth direction of the foundation pit; wherein the content of the first and second substances,

the first support arranged close to the top of the foundation pit is a concrete support;

the second support to the Nth support are sequentially arranged below the first support at intervals, and the second support to the Nth support are all servo steel supports; wherein N is a positive integer greater than or equal to 2.

5. The excavation supporting structure of claim 4, further comprising: a support shaft force servo compensation system connected with the second support to the Nth support;

the support axis force servo compensation system is configured to: applying pre-applied axial force to the second support to the Nth support respectively; and applying axial force to the second support to the Nth support in a grading manner according to the construction progress, and/or applying axial force to the second support to the Nth support according to the deformation condition of the foundation pit and/or the existing building.

6. The excavation supporting structure of claim 5, further comprising: the monitoring system is connected with the supporting shaft force servo compensation system;

the monitoring system is configured to monitor the deformation condition of the foundation pit and the deformation condition of the existing building and transmit the monitored data to the supporting axial force servo compensation system; wherein the deformation condition of the existing building comprises: at least one of a subsidence condition, an inclination condition, a vibration condition, a horizontal displacement condition, and a crack condition of the existing building.

7. The foundation pit supporting structure according to claim 6, wherein along a direction in which the center of the foundation pit points to the boundary of the foundation pit, the area outside the foundation pit is divided into a first affected area, a second affected area, and a third affected area in this order; the shortest distance between the soil body at any position in the first affected area and the foundation pit meets the condition that L is less than or equal to M; the shortest distance between the soil body at any position in the second affected area and the foundation pit meets the condition that M is more than L and less than or equal to 2M; the shortest distance between the soil body at any position in the third affected area and the foundation pit meets the condition that L is more than 2M; wherein L is the shortest distance between the soil outside the foundation pit and the foundation pit; m is an influence range critical value of foundation pit excavation, M is 3H, and H is the average depth of the foundation pit;

the monitoring system comprises a plurality of monitoring components, and the monitoring components are arranged in the first influence area, the second influence area, the third influence area and the outer edge of the foundation pit;

wherein, in the first, second and third influence regions, the arrangement density of the monitoring components decreases in order.

8. The excavation supporting structure of claim 1, further comprising: the foundation pit structure comprises a plurality of upright posts arranged in the foundation pit and a plurality of latticed columns inserted into the upright posts in a one-to-one correspondence mode.

9. The foundation pit support structure of claim 1, wherein the foundation pit support structure further comprises a plurality of dewatering wells; the plurality of dewatering wells include:

at least one pit inner drainage well and at least one pit inner depressurization well which are arranged in the foundation pit;

and at least one pit water level observation well and recharge well which are arranged on the outer side of the underground continuous wall.

10. The excavation supporting structure of claim 1, further comprising a crown beam disposed at a top surface of the excavation, the crown beam being located below the temporary capping layer.