A method for evaluating stability of an underground brick and stone historical relic cave body near a building foundation pit

Abstract

This invention discloses a method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits, comprising the following steps: S1, pre-construction safety and stability assessment and setting of temporary reinforcement measures, including: establishing a discrete model of the brick and stone cultural relic cave, determining horizontal deformation displacement control indicators and vertical deformation displacement control indicators based on the displacement value corresponding to the staggered joint width reaching the preset staggered joint threshold and the displacement value corresponding to the sudden change in slope of the staggered joint width-displacement curve; S13, establishing a dynamic simulation model and determining the maximum allowable vibration velocity; S14, model calibration based on the theoretical calculation results of the support structure; S15, pre-assessment of static safety and stability and dynamic safety and stability; S16, setting of temporary reinforcement measures; S2, safety and stability assessment and adjustment of temporary reinforcement measures during construction; S3, simulation of the entire process of removing temporary reinforcement measures, monitoring and assessing the safety and stability of the brick and stone cultural relic cave during and after removal.

Description

Technical Field

[0001] This invention relates to the field of underground cultural relic building protection technology, specifically to a method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits. Background Technology

[0002] The underground cultural relics are diverse, including mausoleums, air-raid shelters, grotto temples, and underground ruins. These relics not only have historical value but also showcase the architectural wisdom of the ancients. With urban development, when the foundation pits of new buildings are located near underground cultural relic caves, excavation work can easily cause structural damage such as cracking and collapse of the brick and stone cultural relic caves.

[0003] In existing technologies, safety assessments of underground structures adjacent to foundation pits typically employ methods such as conventional finite element analysis, support structure displacement control, surface settlement control, or construction vibration control. While these methods can analyze the deformation and stress state of ordinary underground structures, they still have the following limitations when applied to underground brick and stone cultural relic caves: (1) Existing evaluation indicators are mostly based on overall displacement, stress, settlement or safety factor, which are difficult to reflect early damage characteristics such as misalignment of masonry blocks and local deformation of cave shoulders in brick and stone cultural relics.

[0004] (2) Existing methods often focus on static analysis before construction, lacking a systematic evaluation of dynamic effects such as vibration of construction machinery, vehicle vibration, and vibration of support pile construction, making it difficult to comprehensively judge the safety status of cultural relic caves under the coupling of static and dynamic effects.

[0005] (3) Existing methods usually complete a one-time assessment before construction, lacking a mechanism for dynamic calibration of the model and prediction of the next construction step by combining on-site measured data. When on-site geological conditions, construction procedures or vibration levels change, the assessment results may deviate from the actual situation.

[0006] (4) Existing protection methods focus on setting up temporary reinforcement measures during construction, but do not adequately consider the redistribution of stress and secondary disturbance of the tunnel body during the removal of temporary reinforcement measures, which may create new safety hazards during the removal stage. Summary of the Invention

[0007] The purpose of this invention is to provide a method for assessing the stability of underground brick and stone cultural relic caves near building foundation pits, in order to solve the problems mentioned in the background art, such as insufficient specificity of assessment indicators for underground brick and stone cultural relic caves, incomplete consideration of static and dynamic effects, insufficient dynamic calibration capability during construction, and lack of safety assessment during the temporary reinforcement and demolition stage.

[0008] To achieve the above objectives, the present invention provides a method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits, comprising the following steps: S1. Safety and stability assessment and temporary reinforcement measures before construction, including: S11. Obtain the shape parameters, material mechanical parameters, masonry wave velocity parameters, and geological parameters of the soil around the brick and stone cultural relic cave, and conduct theoretical analysis on the excavation and support scheme of the adjacent building foundation pit. S12. Based on the shape parameters and material mechanics parameters, establish a discrete model of the brick and stone cultural relic cave. According to different horizontal net distances L and different vertical distances H between the foundation pit and the brick and stone cultural relic cave, establish multiple static simulation models. Extract the width of the staggered joints, horizontal displacement and vertical displacement of the bricks at the top of the cave, the left shoulder and the right shoulder respectively. Based on the displacement value corresponding to the staggered joint width reaching the preset staggered joint threshold and the displacement value corresponding to the sudden change in slope of the staggered joint width-displacement curve, determine the horizontal deformation displacement control index S and the vertical deformation displacement control index V. S13. Based on the shape parameters, material mechanical parameters, masonry wave velocity parameters and soil geological parameters, establish a dynamic simulation model, apply the vibration acceleration time history obtained from on-site construction vibration test or similar engineering construction vibration test to the dynamic simulation model, and determine the maximum allowable vibration velocity. S14. Model calibration based on theoretical calculation results of support structure; S15. Pre-assessment of static and dynamic safety and stability; S16. Implement temporary reinforcement measures; S2. Safety and stability assessment and adjustment of temporary reinforcement measures during construction, including: S21. Determine the monitoring plan for the cultural relic cave; S22. Based on the current construction steps, perform model calibration, and based on the calibrated model, perform static and dynamic predictive analysis. S23. Adjust temporary reinforcement measures based on the prediction results; S3. Simulate the entire process of dismantling temporary reinforcement measures, and monitor and assess the safety and stability of the brick and stone cultural relic cave during and after the dismantling process.

[0009] In a preferred embodiment, step S11 involves obtaining the shape parameters, material mechanical parameters, masonry wave velocity parameters, and geological parameters of the surrounding soil of the brick and stone cultural relic cave, and conducting a theoretical analysis of the excavation and support scheme for the adjacent building foundation pit, including: Survey of the form of brick and stone cultural relic caves to obtain the form parameters of the brick and stone cultural relic caves: Use a ruler and total station to survey the cultural relic caves and obtain the overall dimensions of the caves, the dimensions of the bricks and the masonry methods, including staggered joints and header-and-header masonry. Material investigation of brick and stone cultural relic caves to obtain material mechanical parameters and masonry wave velocity parameters: The strength and elastic modulus of the cave materials were measured using a rebound hammer and a universal testing machine to obtain the maximum allowable static compressive stress suitable for static analysis. Maximum allowable static tensile stress Maximum allowable static pressure strain Maximum permissible static tensile strain static elastic modulus To obtain the maximum allowable dynamic stress of the cultural relic cave material suitable for dynamic analysis. Maximum allowable dynamic pressure strain Maximum permissible dynamic tensile strain and kinetic modulus The longitudinal wave velocity of the masonry was measured using a wave velocity meter. ; Geological survey of the soil around the brick and stone cultural relic cave to obtain the geological parameters of the soil around the cave: The soil around the brick and stone cultural relic cave was surveyed by drilling and sampling and ground-penetrating radar to obtain the mechanical properties and thickness of each soil layer around the brick and stone cultural relic cave. Theoretical analysis of the excavation and support scheme for the foundation pit of a nearby building is conducted: the construction is divided into several construction steps according to the construction sequence, and each construction step is numbered accordingly. m According to the conventional calculation method, the first... m The curve showing the change in displacement of the support structure with the height of the foundation pit during the excavation process. , m The value can be 1, 2, 3, ...

[0010] In a preferred embodiment, in step S12, a discrete model of the brick and stone cultural relic cave is established based on the shape parameters and material mechanical parameters. Multiple static simulation models are established according to different horizontal net distances L and vertical distances H between the foundation pit and the brick and stone cultural relic cave. The width of the staggered joints, horizontal displacement, and vertical displacement of the bricks at the cave top, left shoulder, and right shoulder are extracted respectively. Based on the displacement value corresponding to when the staggered joint width reaches a preset staggered joint threshold and the displacement value corresponding to when the slope of the staggered joint width-displacement curve changes abruptly, the horizontal deformation displacement control index S and the vertical deformation displacement control index V are determined, including: Based on the aforementioned shape parameters and material mechanical parameters, a discrete model of the brick and stone cultural relic cave was established in the finite element analysis software. The brick masonry form and material properties were consistent with the survey results. Based on the dimensions of the foundation pit and the support scheme, the range of the horizontal net distance L between the foundation pit and the masonry cave is determined to be a~b, where a is the minimum horizontal net distance and b is the maximum horizontal net distance. The range of the vertical distance H between the top of the foundation pit and the top of the masonry cave is determined to be c~d, where c is the minimum vertical distance and d is the maximum vertical distance. Multiple static simulation models are established by arranging and combining different horizontal clearances L and different vertical distances H. The horizontal clearances are a, 2a, 3a, 4a..., with the maximum value of the horizontal clearance L not exceeding b. The vertical distances H are c, 2c, 3c..., with the maximum value of the vertical distance not exceeding d. Each model is numbered i, where i takes the value 1, 2, 3... For the static simulation model, the excavation of the foundation pit was simulated. The calculation results of the brick and stone tunnel with different horizontal net distances L and different vertical distances H were extracted. The staggered joint width of the bricks at the top of the tunnel and the left and right shoulders of the tunnel were extracted as M(i)-E(j), the horizontal displacement of the bricks at the top of the tunnel and the left and right shoulders of the tunnel relative to the bottom of the tunnel was extracted as M(i)-F(j), and the vertical displacement of the bricks at the top of the tunnel and the left and right shoulders of the tunnel relative to the bottom of the tunnel was extracted as M(i)-G(j). Here, j takes the value of 1, 2, 3, which represent the top of the tunnel, the left shoulder of the tunnel, and the right shoulder of the tunnel, respectively. Establish a cross-sectional width-horizontal displacement curve with M(i)-F(j) as the horizontal coordinate axis and M(i)-E(j) as the vertical coordinate axis. Analyze and record the horizontal displacement value S1(i,j) corresponding to the cross-sectional width reaching the preset cross-sectional threshold in the graph, and analyze and record the horizontal displacement value S2(i,j) corresponding to the curve showing a sudden change in slope in the graph. Take the minimum value between S1(i,j) and S2(i,j) as the horizontal deformation displacement control index S. A curve graph of misalignment width versus vertical displacement is established with M(i)-G(j) as the horizontal coordinate axis and M(i)-E(j) as the vertical coordinate axis. The vertical displacement value V1(i,j) corresponding to the misalignment width reaching the preset misalignment threshold is analyzed and recorded. The vertical displacement value V2(i,j) corresponding to the curve with a sudden change in slope is also analyzed and recorded. The minimum value between V1(i,j) and V2(i,j) is taken as the vertical deformation displacement control index V.

[0011] In a preferred embodiment, in step S13, a dynamic simulation model is established based on the shape parameters, material mechanical parameters, masonry wave velocity parameters, and soil geological parameters. The vibration acceleration time history obtained from on-site construction vibration tests or similar engineering construction vibration tests is applied to the dynamic simulation model to determine the maximum allowable vibration velocity, including: A dynamic simulation model was established based on shape parameters, material mechanics parameters, masonry wave velocity parameters, and soil geological parameters. Before excavation of the foundation pit and construction of the support structure, on-site vibration testing was conducted, or on-site testing was performed in similar projects. Vibration acceleration time history data A during the construction of the on-site support piles was collected, with a peak acceleration of [missing value]. The collected vibration accelerations were applied to the dynamic simulation model of the brick and stone cultural relic cave according to the construction sequence. The time history of the horizontal vibration velocity of the cave ceiling was extracted, and the maximum horizontal velocity of the cave ceiling was analyzed. Extracting the dynamic compressive stress of masonry blocks Dynamic tensile stress Dynamic pressure strain Dynamic tensile strain ; Based on the protection level of the brick and stone cultural relic cave and the longitudinal wave velocity of the masonry Define dynamic safety and stability control indicators and determine the maximum allowable vibration velocity. ; In step S14, model calibration based on the theoretical calculation results of the support structure includes: establishing a numerical simulation analysis model according to the theoretical design scheme, conducting construction simulation analysis based on the support and foundation pit excavation steps, and predicting the construction of the brick and stone cultural relic cave in the first stage. m Displacement of the support structure during each construction step ,like If the numerical simulation analysis model results are consistent with the theoretical calculation results of the support structure, then the numerical simulation analysis model results are accurate. If the numerical simulation analysis results do not meet the above requirements, the model should be adjusted for the mesh size, elastic modulus of the support structure, and relevant soil parameters until the numerical simulation analysis results are consistent with the theoretical calculation results.

[0012] In a preferred embodiment, in step S15, the static safety and stability pre-assessment involves establishing a numerical simulation analysis model based on existing foundation pit excavation and support scheme theories and exploration results, conducting construction simulation analysis based on actual support and foundation pit excavation steps, and extracting the brick and stone cultural relic cave body in the first... m Static analysis of the tunnel's horizontal displacement during each construction step Static analysis of the vertical displacement of the tunnel body Static analysis of tunnel stress Static analysis of tunnel strain ,like If the current support design does not meet the requirements, the support design should be adjusted. If the support design still does not meet the requirements after adjustment, the excavation of the foundation pit has a significant impact on the safety and stability of the underground brick and stone cultural relic cave, and the result of the judgment of avoidance or adjustment of the construction plan is output. The dynamic safety and stability pre-assessment involves establishing a numerical simulation analysis model based on existing foundation pit and support theories and exploration results. Construction simulation analysis is then conducted based on the actual support and foundation pit excavation steps, extracting data from the brick and stone cultural relic cave structure at the [missing information - likely a specific location or stage]. m The maximum horizontal displacement of the tunnel during each construction step was analyzed. Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel stress Dynamic analysis of tunnel strain Dynamic analysis of tunnel velocity ,like or If the vibrations from the current construction machinery and vehicles are deemed to have a significant impact on the underground brick and stone cultural relic cave, the machinery and equipment and construction plan should be adjusted. If the requirements are still not met, a new site should be selected to avoid the impact.

[0013] In a preferred embodiment, in step S16, the temporary reinforcement measure is to enhance the compressive stiffness of the brick and stone cultural relic cave by setting internal supports inside the cave, and the measures are adjusted according to different degrees of influence. The influence coefficient of the excavation pit on the static safety and stability of the brick and stone cultural relic cave is: The impact coefficient of the foundation pit excavation on the dynamic safety and stability of the brick and stone cultural relic cave is: ;like If the excavation of the foundation pit has a minor impact on the brick and stone cultural relic cave, then temporary reinforcement measures are not required. If the impact of the foundation pit excavation on the brick and stone cultural relic cave is deemed moderate, then temporary reinforcement measures should be installed at intervals of 5 meters. If the excavation of the foundation pit has a significant impact on the brick and stone cultural relic cave, then the temporary reinforcement measures should be set at intervals of 2-5m. If the excavation of the foundation pit has a significant impact on the brick and stone cultural relic cave, then the spacing of the temporary reinforcement measures should not exceed 1m.

[0014] In a preferred embodiment, step S21, determining the monitoring scheme for the cultural relic cave, includes: setting displacement and velocity sensors inside the cave and at the support boundary according to the trend of the brick and stone cultural relic cave, and acquiring the horizontal displacement of the brick and stone cave during the excavation process of the foundation pit at each excavation step. Vertical displacement Horizontal speed Displacement and velocity sensors shall be installed on each cross section of each tunnel, at least at the tunnel top and on both sides of the tunnel shoulders, with a maximum spacing of 5m between each cross section.

[0015] In a preferred embodiment, step S22, model calibration based on the current construction step, is as follows: when the site is in the process of foundation pit excavation, when the construction site completes the first... m After the first construction step, the numerical simulation analysis of the first step is extracted. m Displacement of the support structure during each construction step ,like If the numerical simulation results match the theoretical calculations, the model's calculations are accurate. If the numerical simulation results do not meet these requirements, the model should be adjusted regarding the mesh size, elastic modulus of the support structure, and soil parameters until the simulation results match the theoretical calculations. The first step is to extract the first... m Static analysis of the tunnel's horizontal displacement during each construction step Static analysis of the vertical displacement of the tunnel body Dynamic analysis of the horizontal displacement of the tunnel body Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel velocity ,like , If the results are consistent, it means that the numerical simulation analysis model's calculation results of the cultural relic cave structure are consistent with the measured results, and the numerical simulation analysis model's calculation results are accurate. If the numerical simulation analysis calculation results do not meet the above requirements, the model should be adjusted for the mesh size, the elastic modulus of the cultural relic cave material structure, and the parameters of the soil adjacent to the cultural relic cave until the simulation analysis results of the cultural relic cave are consistent with the theoretical calculation results.

[0016] In a preferred embodiment, step S22, performing static and dynamic prediction analyses based on the calibration model, includes: extracting the brick and stone cultural relic cave body in the first... m+ The predicted horizontal displacement of the tunnel obtained from static analysis in one construction step Static analysis of the vertical displacement of the tunnel body Static analysis of tunnel stress Static analysis of tunnel strain , If the current support design does not meet the requirements for the subsequent protection of the brick and stone cultural relic cave, the support design should be adjusted; the brick and stone cultural relic cave should be extracted in the [missing information]. m + Predicted horizontal displacement of the tunnel obtained from dynamic analysis in one construction step Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel stress Dynamic analysis of tunnel strain Dynamic analysis of tunnel velocity ,like If the vibration of the current construction machinery and vehicles is determined to have a significant impact on the underground brick and stone cultural relic cave in the subsequent construction steps, the machinery and equipment, construction plan and support plan should be adjusted.

[0017] In a preferred embodiment, step S3 involves simulating the entire process of dismantling the temporary reinforcement measures, monitoring the brick and stone cultural relic cave and assessing its safety and stability during and after the dismantling process, including: S31. Safety and stability assessment of the cave structure during the removal of reinforcement measures: Simulation of the entire process of removing reinforcement measures, and extraction of brick and stone cultural relics from the cave structure in the [missing information]. k Horizontal displacement of the tunnel during each construction step Vertical displacement of the tunnel body Stress in the tunnel Strain of the tunnel ,in k The values ​​can be 1, 2, 3...; if If the current temporary reinforcement measures removal plan meets the requirements, it can be removed according to this plan. If it does not meet the above requirements, the temporary reinforcement measures removal plan should be adjusted and numerical simulation should be performed again. If it still does not meet the requirements, it is determined that the reinforcement measures are under too much stress and cannot be removed. S32. Monitoring after removal of temporary reinforcement measures: Continuous monitoring will be conducted after the removal of temporary reinforcement measures to obtain the horizontal displacement of the masonry tunnel during the excavation process of the foundation pit at each step of the removal of temporary reinforcement devices. and vertical displacement ; S33. Safety and stability assessment of the cave after demolition: If the temporary reinforcement measures are removed, the horizontal displacement of the brick and stone cultural relic cave will be continuously monitored during the subsequent period. And vertical displacement If the temporary reinforcement device is removed, the brick and stone cultural relic cave is determined to be in a safe and stable state, and the assessment is concluded.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses the width of the staggered joints of bricks in brick and stone cultural relic caves as a damage characterization quantity, and determines the horizontal deformation displacement control index and the vertical deformation displacement control index through the staggered joint width-horizontal displacement curve and the staggered joint width-vertical displacement curve, so that the safety evaluation index is more in line with the structural characteristics and damage mechanism of brick and stone cultural relic caves.

[0019] 2. This invention establishes static simulation models and dynamic simulation models respectively, which can simultaneously evaluate the static disturbances caused by foundation pit excavation and the dynamic disturbances caused by construction machinery, vehicles, and support pile construction, thereby improving the comprehensiveness of stability assessment.

[0020] 3. This invention can make dynamic predictions based on construction steps and adjust temporary reinforcement measures, support design schemes, construction machinery and equipment or construction schemes in a timely manner based on the prediction results, and has strong on-site adaptability and engineering operability.

[0021] 4. This invention incorporates the entire process of removing temporary reinforcement measures into a safety and stability assessment, which can prevent damage to the cultural relic cave due to stress redistribution or secondary disturbance during the reinforcement and removal stage, thereby improving the safety of the entire process of cultural relic protection.

[0022] 5. This invention forms a closed-loop assessment system that includes pre-construction assessment, in-construction monitoring, calibration and prediction, dynamic adjustment of temporary reinforcement, and safety confirmation after demolition. It is applicable to the protection of underground brick and stone cultural relic caves near building foundation pits. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the overall steps of the method of the present invention; Figure 2 A flowchart illustrating the steps for safety and stability assessment and temporary reinforcement measures before construction of this invention. Figure 3 This is a diagram showing the cross-sectional width versus horizontal displacement in an embodiment of the present invention. Figure 4 This is a curve showing the difference between the width of the staggered joint and the vertical displacement in an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of the present invention.

[0025] like Figures 1 to 4 As shown, this invention provides a method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits. These underground brick and stone cultural relic caves can be brick-arched caves, underground corridors, underground palace passages, air-raid shelters, underground archaeological chambers, or other underground cultural relic spaces formed using brick and stone masonry. The adjacent building foundation pit can be a basement foundation pit for a new building, an underground passage foundation pit, a pipe gallery foundation pit, or other foundation pit excavated near a cultural relic cave.

[0026] The method of the present invention includes the following steps: Step S1, Safety and Stability Assessment and Temporary Reinforcement Measures Before Construction, specifically includes: Step S11: Obtain the shape parameters, material mechanical parameters, masonry wave velocity parameters, and geological parameters of the soil surrounding the brick and stone cultural relic cave, and conduct theoretical analysis on the excavation and support scheme of the adjacent building foundation pit.

[0027] Specifically, the survey of the brick and stone cultural relic cave structure will obtain the structural parameters of the brick and stone cultural relic cave structure: the cave structure will be surveyed using a ruler and a total station to obtain the overall dimensions of the cave structure, the dimensions of the bricks and the masonry method, including staggered joints, header and header masonry or other traditional masonry forms.

[0028] Material investigation of brick and stone cultural relic caves to obtain material mechanical parameters and masonry wave velocity parameters: The strength and elastic modulus of the cave materials were measured using a rebound hammer and a universal testing machine to obtain the maximum allowable static compressive stress suitable for static analysis. Maximum allowable static tensile stress Maximum allowable static pressure strain Maximum permissible static tensile strain static elastic modulus To obtain the maximum allowable dynamic stress of the cultural relic cave material suitable for dynamic analysis. Maximum allowable dynamic pressure strain Maximum permissible dynamic tensile strain and kinetic modulus The longitudinal wave velocity of the masonry was measured using a wave velocity meter. ; Geological survey of the soil around the brick and stone cultural relic cave to obtain the geological parameters of the soil around the cave: The soil around the brick and stone cultural relic cave was surveyed by drilling and sampling and ground-penetrating radar to obtain the mechanical properties and thickness of each soil layer around the brick and stone cultural relic cave. Theoretical analysis of the excavation and support scheme for the foundation pit of a nearby building is conducted: the construction is divided into several construction steps according to the construction sequence, and each construction step is numbered accordingly. m According to the conventional calculation method, the first... m The curve showing the change in displacement of the support structure with the height of the foundation pit during the excavation process. , m The value can be 1, 2, 3, ...

[0029] Step S12: Based on the shape parameters and material mechanics parameters, establish a discrete model of the brick and stone cultural relic cave. Establish multiple static simulation models according to different horizontal net distances L and different vertical distances H between the foundation pit and the brick and stone cultural relic cave. Extract the width of the staggered joints, horizontal displacement and vertical displacement of the bricks at the top of the cave, the left shoulder and the right shoulder respectively. Determine the horizontal deformation displacement control index S and the vertical deformation displacement control index V according to the displacement value corresponding to the staggered joint width reaching the preset staggered joint threshold and the displacement value corresponding to the slope change of the staggered joint width-displacement curve.

[0030] Specifically, based on the aforementioned shape parameters and material mechanical parameters, a discrete model of the brick and stone cultural relic cave was established in the finite element analysis software, and the brick masonry form and material properties were consistent with the survey results. Based on the dimensions of the foundation pit and the support scheme, the range of the horizontal net distance L between the foundation pit and the masonry cave is determined to be a~b, where a is the minimum horizontal net distance and b is the maximum horizontal net distance. The range of the vertical distance H between the top of the foundation pit and the top of the masonry cave is determined to be c~d, where c is the minimum vertical distance and d is the maximum vertical distance. Multiple static simulation models are established by arranging and combining different horizontal clearances L and different vertical distances H. The horizontal clearances are a, 2a, 3a, 4a..., with the maximum value of the horizontal clearance L not exceeding b. The vertical distances H are c, 2c, 3c..., with the maximum value of the vertical distance not exceeding d. Each model is numbered i, where i takes the value 1, 2, 3... For the static simulation model, the excavation of the foundation pit was simulated. The calculation results of the brick and stone tunnel with different horizontal net distances L and different vertical distances H were extracted. The staggered joint width of the bricks at the top of the tunnel and the left and right shoulders of the tunnel were extracted as M(i)-E(j), the horizontal displacement of the bricks at the top of the tunnel and the left and right shoulders of the tunnel relative to the bottom of the tunnel was extracted as M(i)-F(j), and the vertical displacement of the bricks at the top of the tunnel and the left and right shoulders of the tunnel relative to the bottom of the tunnel was extracted as M(i)-G(j). Here, j takes the value of 1, 2, 3, which represent the top of the tunnel, the left shoulder of the tunnel, and the right shoulder of the tunnel, respectively. Establish a cross-sectional width-horizontal displacement curve with M(i)-F(j) as the horizontal coordinate axis and M(i)-E(j) as the vertical coordinate axis. Analyze and record the horizontal displacement value S1(i,j) corresponding to the cross-sectional width reaching the preset cross-sectional threshold in the graph, and analyze and record the horizontal displacement value S2(i,j) corresponding to the curve showing a sudden change in slope in the graph. Take the minimum value between S1(i,j) and S2(i,j) as the horizontal deformation displacement control index S. A curve graph of misalignment width versus vertical displacement is established with M(i)-G(j) as the horizontal coordinate axis and M(i)-E(j) as the vertical coordinate axis. The vertical displacement value V1(i,j) corresponding to the misalignment width reaching the preset misalignment threshold is analyzed and recorded. The vertical displacement value V2(i,j) corresponding to the curve with a sudden change in slope is also analyzed and recorded. The minimum value between V1(i,j) and V2(i,j) is taken as the vertical deformation displacement control index V.

[0031] Preferably, the preset staggered joint threshold is 10mm, but the preset staggered joint threshold can also be adjusted according to the cultural relic protection level, the preservation status of the cave, the size of the bricks, or the degree of existing damage.

[0032] Step S13: Based on the shape parameters, material mechanical parameters, masonry wave velocity parameters and soil geological parameters, establish a dynamic simulation model, apply the vibration acceleration time history obtained from on-site construction vibration test or similar engineering construction vibration test to the dynamic simulation model, and determine the maximum allowable vibration velocity.

[0033] Specifically, this includes: establishing a dynamic simulation model based on shape parameters, material mechanical parameters, masonry wave velocity parameters, and soil geological parameters; conducting on-site construction vibration tests or similar tests before foundation pit excavation and support structure construction; collecting vibration acceleration time history data A during on-site support pile construction, with a peak acceleration of... The collected vibration accelerations were applied to the dynamic simulation model of the brick and stone cultural relic cave according to the construction sequence. The time history of the horizontal vibration velocity of the cave ceiling was extracted, and the maximum horizontal velocity of the cave ceiling was analyzed. Extracting the dynamic compressive stress of masonry blocks Dynamic tensile stress Dynamic pressure strain Dynamic tensile strain ; Based on the protection level of the brick and stone cultural relic cave and the longitudinal wave velocity of the masonry Define dynamic safety and stability control indicators and determine the maximum allowable vibration velocity. If the vibration velocity, dynamic stress, or dynamic strain in the dynamic simulation results exceed the corresponding control indicators, it is determined that the construction vibration has an adverse effect on the brick and stone cultural relic cave.

[0034] In step S14, model calibration based on the theoretical calculation results of the support structure includes: establishing a numerical simulation analysis model according to the theoretical design scheme, conducting construction simulation analysis based on the support and foundation pit excavation steps, and predicting the construction of the brick and stone cultural relic cave in the first stage. m Displacement of the support structure during each construction step ,like If the numerical simulation analysis model results are consistent with the theoretical calculation results of the support structure, then the numerical simulation analysis model results are accurate. If the numerical simulation analysis results do not meet the above requirements, the model should be adjusted for the mesh size, elastic modulus of the support structure, and relevant soil parameters until the numerical simulation analysis results are consistent with the theoretical calculation results.

[0035] Step S15: Pre-assessment of static and dynamic safety and stability.

[0036] Specifically, the static safety and stability pre-assessment involves establishing a numerical simulation analysis model based on existing foundation pit excavation and support scheme theories and exploration results. Construction simulation analysis is then conducted based on the actual support and foundation pit excavation steps, extracting data from the brick and stone cultural relic cave structure at the [missing information - likely a specific location or stage]. m Static analysis of the tunnel's horizontal displacement during each construction step Static analysis of the vertical displacement of the tunnel body Static analysis of tunnel stress Static analysis of tunnel strain ,like If the current support design does not meet the requirements, the support design should be adjusted. If the support design still does not meet the requirements after adjustment, the excavation of the foundation pit has a significant impact on the safety and stability of the underground brick and stone cultural relic cave, and the result of the judgment of avoidance or adjustment of the construction plan is output. The dynamic safety and stability pre-assessment involves establishing a numerical simulation analysis model based on existing foundation pit and support theories and exploration results. Construction simulation analysis is then conducted based on the actual support and foundation pit excavation steps, extracting data from the brick and stone cultural relic cave structure at the [missing information - likely a specific location or stage]. m The maximum horizontal displacement of the tunnel during each construction step was analyzed. Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel stress Dynamic analysis of tunnel strain Dynamic analysis of tunnel velocity ,like or If the vibrations from the current construction machinery and vehicles are deemed to have a significant impact on the underground brick and stone cultural relic cave, the machinery and equipment and construction plan should be adjusted. If the requirements are still not met, a new site should be selected to avoid the impact.

[0037] Step S16: Set up temporary reinforcement measures.

[0038] Based on the preliminary assessment results of static and dynamic safety and stability, the static and dynamic safety and stability impact coefficients of the excavation of the foundation pit on the brick and stone cultural relic cave were determined. The static safety and stability impact coefficient of the foundation pit excavation on the brick and stone cultural relic cave is as follows: The impact coefficient of the foundation pit excavation on the dynamic safety and stability of the brick and stone cultural relic cave is: ;like If the excavation of the foundation pit has a minor impact on the brick and stone cultural relic cave, then temporary reinforcement measures are not required. If the impact of the foundation pit excavation on the brick and stone cultural relic cave is deemed moderate, then temporary reinforcement measures should be installed at intervals of 5 meters. If the excavation of the foundation pit has a significant impact on the brick and stone cultural relic cave, then the temporary reinforcement measures should be set at intervals of 2-5m. If the excavation of the foundation pit has a significant impact on the brick and stone cultural relic cave, then the spacing of the temporary reinforcement measures should not exceed 1m.

[0039] Temporary reinforcement measures can utilize internal support structures within the cave. These internal support structures can include steel supports, wooden supports, adjustable support frames, arched support frames, or other reversible support structures that do not damage the artifact itself. When implementing temporary reinforcement measures, drilling, cutting, chiseling, or other irreversible damage to the artifact should be avoided as much as possible.

[0040] Step S2, safety and stability assessment and adjustment of temporary reinforcement measures during construction, specifically includes: Step S21: Determine the monitoring plan for the cultural relic cave: This includes setting displacement and velocity sensors inside the cave and at the support boundary according to the trend of the brick and stone cultural relic cave, and acquiring the horizontal displacement of the brick and stone cave during the excavation process of the foundation pit at each excavation step. Vertical displacement Horizontal speed Displacement and velocity sensors should be installed at least at the top of the tunnel and on both sides of the tunnel shoulders on each cross-section within each tunnel, with a maximum spacing of 5 meters between each cross-section. For areas with severe damage, areas closest to the foundation pit, tunnel turning areas, or structurally weak areas, the number of monitoring cross-sections can be increased.

[0041] Step S22: Perform model calibration based on the current construction steps, and perform static and dynamic prediction analysis based on the calibrated model.

[0042] The model calibration based on the current construction steps is as follows: when the site is in the process of foundation pit excavation, when the construction site completes the first... m After the first construction step, the numerical simulation analysis of the first step is extracted. m Displacement of the support structure during each construction step ,like If the numerical simulation results match the theoretical calculations, the model's calculations are accurate. If the numerical simulation results do not meet these requirements, the model should be adjusted regarding the mesh size, elastic modulus of the support structure, and soil parameters until the simulation results match the theoretical calculations. The first step is to extract the first... m Static analysis of the tunnel's horizontal displacement during each construction step Static analysis of the vertical displacement of the tunnel body Dynamic analysis of the horizontal displacement of the tunnel body Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel velocity ,like , If the results are consistent, it means that the numerical simulation analysis model's calculation results of the cultural relic cave structure are consistent with the measured results, and the numerical simulation analysis model's calculation results are accurate. If the numerical simulation analysis calculation results do not meet the above requirements, the model should be adjusted for the mesh size, the elastic modulus of the cultural relic cave material structure, and the parameters of the soil adjacent to the cultural relic cave until the simulation analysis results of the cultural relic cave are consistent with the theoretical calculation results.

[0043] Static prediction analysis based on a calibration model includes: extracting the structural parameters of the brick and stone cultural relic cave in the first quarter. m+ The predicted horizontal displacement of the tunnel obtained from static analysis in one construction step Static analysis of the vertical displacement of the tunnel body Static analysis of tunnel stress Static analysis of tunnel strain , If the current support design does not meet the requirements for the protection of the brick and stone cultural relic cave, the support design should be adjusted.

[0044] Dynamic prediction analysis based on a calibration model includes: extracting the geological features of brick and stone cultural relics caves in the first quarter. m+ Predicted horizontal displacement of the tunnel obtained from dynamic analysis in one construction step Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel stress Dynamic analysis of tunnel strain Dynamic analysis of tunnel velocity ,like If the vibration of the current construction machinery and vehicles is determined to have a significant impact on the underground brick and stone cultural relic cave in the subsequent construction steps, the machinery and equipment, construction plan and support plan should be adjusted.

[0045] Step S23: Adjust temporary reinforcement measures based on the prediction results. According to the... m Based on the static and dynamic predictive analysis results of the +1 construction step, adjustments can be made to the temporary reinforcement measures. When the predicted results are close to but do not exceed the control targets, measures such as increasing monitoring frequency, reducing construction speed, restricting the approach of heavy machinery, and optimizing vehicle transportation routes can be taken. When the predicted results exceed the control targets, temporary reinforcement measures should be added, the spacing between temporary supports should be reduced, the stiffness of the supports should be increased, the excavation sequence of the foundation pit should be adjusted, or the support scheme should be modified. If the control target requirements still cannot be met after taking the above measures, the relevant construction steps should be suspended, and the construction plan should be re-evaluated or avoidance measures should be taken.

[0046] Step S3: Simulate the entire process of dismantling the temporary reinforcement measures, and monitor and assess the safety and stability of the brick and stone cultural relic cave during and after the dismantling process.

[0047] Step S31, Safety and Stability Assessment of the Cave During the Reinforcement Measures Removal Process: Simulate the entire process of removing the reinforcement measures and extract the brick and stone cultural relic cave body in the first step. k Horizontal displacement of the tunnel during each construction step Vertical displacement of the tunnel body Stress in the tunnel Strain of the tunnel ,in k The values ​​can be 1, 2, 3...; if If the current temporary reinforcement measures removal plan meets the requirements, it can be removed according to this plan. If it does not meet the above requirements, the temporary reinforcement measures removal plan should be adjusted and numerical simulation should be performed again. If it still does not meet the requirements, it is determined that the reinforcement measures are under too much stress and cannot be removed. S32. Monitoring after removal of temporary reinforcement measures: Continuous monitoring will be conducted after the removal of temporary reinforcement measures to obtain the horizontal displacement of the masonry tunnel during the excavation process of the foundation pit at each step of the removal of temporary reinforcement devices. and vertical displacement ; S33. Safety and stability assessment of the cave after demolition: If the temporary reinforcement measures are removed, the horizontal displacement of the brick and stone cultural relic cave will be continuously monitored during the subsequent period. And vertical displacement If the temporary reinforcement device is removed, the brick and stone cultural relic cave is deemed to be in a safe and stable state, and the assessment is concluded. If the monitoring data exceeds the control indicators after removal, or if new structural damage occurs, temporary supports should be reinstalled or other protective measures should be taken, and a new safety and stability assessment should be conducted.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for evaluating the stability of an underground masonry cultural relic cave body adjacent to a building foundation pit, characterized in that: Includes the following steps: S1. Safety and stability assessment and temporary reinforcement measures before construction, including: S11. Obtain the shape parameters, material mechanical parameters, masonry wave velocity parameters, and geological parameters of the soil around the brick and stone cultural relic cave, and conduct theoretical analysis on the excavation and support scheme of the adjacent building foundation pit. S12. Based on the shape parameters and material mechanics parameters, establish a discrete model of the brick and stone cultural relic cave. According to different horizontal net distances L and different vertical distances H between the foundation pit and the brick and stone cultural relic cave, establish multiple static simulation models. Extract the width of the staggered joints, horizontal displacement and vertical displacement of the bricks at the top of the cave, the left shoulder and the right shoulder respectively. Based on the displacement value corresponding to the staggered joint width reaching the preset staggered joint threshold and the displacement value corresponding to the sudden change in slope of the staggered joint width-displacement curve, determine the horizontal deformation displacement control index S and the vertical deformation displacement control index V. S13. Based on the shape parameters, material mechanical parameters, masonry wave velocity parameters and soil geological parameters, establish a dynamic simulation model, apply the vibration acceleration time history obtained from on-site construction vibration test or similar engineering construction vibration test to the dynamic simulation model, and determine the maximum allowable vibration velocity. S14. Model calibration based on theoretical calculation results of support structure; S15. Pre-assessment of static and dynamic safety and stability; S16. Implement temporary reinforcement measures; S2. Safety and stability assessment and adjustment of temporary reinforcement measures during construction, including: S21. Determine the monitoring plan for the cultural relic cave; S22. Based on the current construction steps, perform model calibration, and based on the calibrated model, perform static and dynamic predictive analysis. S23. Adjust temporary reinforcement measures based on the prediction results; S3. Simulate the entire process of dismantling temporary reinforcement measures, and monitor and assess the safety and stability of the brick and stone cultural relic cave during and after the dismantling process.

2. The method for evaluating the stability of underground masonry cultural heritage cavities adjacent to building foundation pits according to claim 1, characterized in that: In step S11, the shape parameters, material mechanical parameters, masonry wave velocity parameters, and geological parameters of the surrounding soil of the brick and stone cultural relic cave are obtained. A theoretical analysis is also conducted on the excavation and support scheme for the adjacent building foundation pit, including: Survey of the form of brick and stone cultural relic caves to obtain the form parameters of the brick and stone cultural relic caves: Use a ruler and total station to survey the cultural relic caves and obtain the overall dimensions of the caves, the dimensions of the bricks and the masonry methods, including staggered joints and header-and-header masonry. Material investigation of brick and stone cultural relic caves to obtain material mechanical parameters and masonry wave velocity parameters: The strength and elastic modulus of the cave materials were measured using a rebound hammer and a universal testing machine to obtain the maximum allowable static compressive stress suitable for static analysis. Maximum allowable static tensile stress Maximum allowable static pressure strain Maximum permissible static tensile strain static elastic modulus To obtain the maximum allowable dynamic stress of the cultural relic cave material suitable for dynamic analysis. Maximum allowable dynamic pressure strain Maximum permissible dynamic tensile strain and kinetic modulus The longitudinal wave velocity of the masonry was measured using a wave velocity meter. ; Geological survey of the soil around the brick and stone cultural relic cave to obtain the geological parameters of the soil around the cave: The soil around the brick and stone cultural relic cave was surveyed by drilling and sampling and ground-penetrating radar to obtain the mechanical properties and thickness of each soil layer around the brick and stone cultural relic cave. Theoretical analysis of the excavation and support scheme for the foundation pit of a nearby building is conducted: the construction is divided into several construction steps according to the construction sequence, and each construction step is numbered accordingly. m According to the conventional calculation method, the first... m The curve showing the change in displacement of the support structure with the height of the foundation pit during the excavation process. , m The value can be 1, 2, 3, ...

3. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits as described in claim 1, characterized in that: In step S12, a discrete model of the brick and stone cultural relic cave is established based on the shape parameters and material mechanics parameters. Multiple static simulation models are established according to different horizontal net distances L and vertical distances H between the foundation pit and the brick and stone cultural relic cave. The width of the staggered joints, horizontal displacement, and vertical displacement of the bricks at the cave top, left shoulder, and right shoulder are extracted respectively. Based on the displacement value corresponding to when the staggered joint width reaches a preset staggered joint threshold and the displacement value corresponding to when the slope of the staggered joint width-displacement curve changes abruptly, the horizontal deformation displacement control index S and the vertical deformation displacement control index V are determined, including: Based on the aforementioned shape parameters and material mechanical parameters, a discrete model of the brick and stone cultural relic cave was established in the finite element analysis software. The brick masonry form and material properties were consistent with the survey results. Based on the dimensions of the foundation pit and the support scheme, the range of the horizontal net distance L between the foundation pit and the masonry cave is determined to be a~b, where a is the minimum horizontal net distance and b is the maximum horizontal net distance. The range of the vertical distance H between the top of the foundation pit and the top of the masonry cave is determined to be c~d, where c is the minimum vertical distance and d is the maximum vertical distance. Multiple static simulation models are established by arranging and combining different horizontal clearances L and different vertical distances H. The horizontal clearances are a, 2a, 3a, 4a..., with the maximum value of the horizontal clearance L not exceeding b. The vertical distances H are c, 2c, 3c..., with the maximum value of the vertical distance not exceeding d. Each model is numbered i, where i takes the value 1, 2, 3... For the static simulation model, the excavation of the foundation pit was simulated. The calculation results of the brick and stone tunnel with different horizontal net distances L and different vertical distances H were extracted. The staggered joint width of the bricks at the top of the tunnel and the left and right shoulders of the tunnel were extracted as M(i)-E(j), the horizontal displacement of the bricks at the top of the tunnel and the left and right shoulders of the tunnel relative to the bottom of the tunnel was extracted as M(i)-F(j), and the vertical displacement of the bricks at the top of the tunnel and the left and right shoulders of the tunnel relative to the bottom of the tunnel was extracted as M(i)-G(j). Here, j takes the value of 1, 2, 3, which represent the top of the tunnel, the left shoulder of the tunnel, and the right shoulder of the tunnel, respectively. Establish a cross-sectional width-horizontal displacement curve with M(i)-F(j) as the horizontal coordinate axis and M(i)-E(j) as the vertical coordinate axis. Analyze and record the horizontal displacement value S1(i,j) corresponding to the cross-sectional width reaching the preset cross-sectional threshold in the graph, and analyze and record the horizontal displacement value S2(i,j) corresponding to the curve showing a sudden change in slope in the graph. Take the minimum value between S1(i,j) and S2(i,j) as the horizontal deformation displacement control index S. A curve graph of misalignment width versus vertical displacement is established with M(i)-G(j) as the horizontal coordinate axis and M(i)-E(j) as the vertical coordinate axis. The vertical displacement value V1(i,j) corresponding to the misalignment width reaching the preset misalignment threshold is analyzed and recorded. The vertical displacement value V2(i,j) corresponding to the curve with a sudden change in slope is also analyzed and recorded. The minimum value between V1(i,j) and V2(i,j) is taken as the vertical deformation displacement control index V.

4. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits as described in claim 3, characterized in that: In step S13, a dynamic simulation model is established based on the shape parameters, material mechanical parameters, masonry wave velocity parameters, and soil geological parameters. The vibration acceleration time history obtained from on-site construction vibration tests or similar engineering construction vibration tests is applied to the dynamic simulation model to determine the maximum allowable vibration velocity, including: A dynamic simulation model is established based on the aforementioned shape parameters, material mechanical parameters, masonry wave velocity parameters, and soil geological parameters. Before excavation of the foundation pit and construction of the support structure, on-site vibration testing is conducted, or on-site testing is performed in similar projects. Vibration acceleration time history data A during the construction of the on-site support piles is collected, with a peak acceleration of [missing value]. The collected vibration accelerations were applied to the dynamic simulation model of the brick and stone cultural relic cave according to the construction sequence. The time history of the horizontal vibration velocity of the cave ceiling was extracted, and the maximum horizontal velocity of the cave ceiling was analyzed. Extracting the dynamic compressive stress of masonry blocks Dynamic tensile stress Dynamic pressure strain Dynamic tensile strain ; Based on the protection level of the brick and stone cultural relic cave and the longitudinal wave velocity of the masonry Define dynamic safety and stability control indicators and determine the maximum allowable vibration velocity. ; In step S14, model calibration based on the theoretical calculation results of the support structure includes: establishing a numerical simulation analysis model according to the theoretical design scheme, conducting construction simulation analysis based on the support and foundation pit excavation steps, and predicting the construction of the brick and stone cultural relic cave in the first stage. m Displacement of the support structure during each construction step ,like If the numerical simulation analysis model results are consistent with the theoretical calculation results of the support structure, then the numerical simulation analysis model results are accurate. If the numerical simulation analysis results do not meet the above requirements, the model should be adjusted for the mesh size, elastic modulus of the support structure, and relevant soil parameters until the numerical simulation analysis results are consistent with the theoretical calculation results.

5. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits as described in claim 1, characterized in that: In step S15, the static safety and stability pre-assessment involves establishing a numerical simulation analysis model based on existing foundation pit excavation and support scheme theories and exploration results. Construction simulation analysis is then conducted based on the actual support and foundation pit excavation steps, extracting data from the brick and stone cultural relic cave in the [missing information - likely a specific step or section]. m Static analysis of the tunnel's horizontal displacement during each construction step Static analysis of the vertical displacement of the tunnel body Static analysis of tunnel stress Static analysis of tunnel strain ,like If the current support design does not meet the requirements, the support design should be adjusted. If the support design still does not meet the requirements after adjustment, the excavation of the foundation pit has a significant impact on the safety and stability of the underground brick and stone cultural relic cave, and the result of the judgment of avoidance or adjustment of the construction plan is output. The dynamic safety and stability pre-assessment involves establishing a numerical simulation analysis model based on existing foundation pit and support theories and exploration results. Construction simulation analysis is then conducted based on the actual support and foundation pit excavation steps, extracting data from the brick and stone cultural relic cave structure at the [missing information - likely a specific location or stage]. m The maximum horizontal displacement of the tunnel during each construction step was analyzed. Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel stress Dynamic analysis of tunnel strain Dynamic analysis of tunnel velocity ,like or If the vibrations from the current construction machinery and vehicles are deemed to have a significant impact on the underground brick and stone cultural relic cave, the machinery and equipment and construction plan should be adjusted. If the requirements are still not met, a new site should be selected to avoid the impact.

6. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits according to claim 1, characterized in that: In step S16, temporary reinforcement measures are implemented by installing internal supports inside the brick and stone cultural relic cave to enhance its compressive stiffness. Adjustments are made based on different levels of impact. The impact coefficient of the excavation pit on the static safety and stability of the brick and stone cultural relic cave is: The impact coefficient of the foundation pit excavation on the dynamic safety and stability of the brick and stone cultural relic cave is: ;like If the excavation of the foundation pit has a minor impact on the brick and stone cultural relic cave, then temporary reinforcement measures are not required. If the impact of the foundation pit excavation on the brick and stone cultural relic cave is deemed moderate, then temporary reinforcement measures should be installed at intervals of 5 meters. If the excavation of the foundation pit has a significant impact on the brick and stone cultural relic cave, then the temporary reinforcement measures should be set at intervals of 2-5m. If the excavation of the foundation pit has a significant impact on the brick and stone cultural relic cave, then the spacing of the temporary reinforcement measures should not exceed 1m.

7. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits as described in claim 6, characterized in that: In step S21, the monitoring plan for the cultural relic cave is determined, including: setting displacement and velocity sensors inside the cave and at the support boundary according to the trend of the brick and stone cultural relic cave, and acquiring the horizontal displacement of the brick and stone cave during the excavation process of the foundation pit at each excavation step. Vertical displacement Horizontal speed Displacement and velocity sensors shall be installed on each cross section of each tunnel, at least at the tunnel top and on both sides of the tunnel shoulders, with a maximum spacing of 5m between each cross section.

8. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits as described in claim 7, characterized in that: In step S22, model calibration based on the current construction step is performed as follows: when the site is in the process of foundation pit excavation, when the construction site completes the first... m After the first construction step, the numerical simulation analysis of the first step is extracted. m Displacement of the support structure during each construction step ,like If the numerical simulation analysis model's calculation results for the support structure are consistent with the theoretical calculation results, then the numerical simulation analysis model's calculation results are accurate. If the numerical analysis calculation results do not meet the above requirements, then the model should be adjusted for the mesh size, the elastic modulus of the support structure, and the relevant soil parameters until the simulation analysis results are consistent with the theoretical calculation results. Extraction of the brick and stone cave body m Static analysis of the tunnel's horizontal displacement during each construction step Static analysis of the vertical displacement of the tunnel body Dynamic analysis of the horizontal displacement of the tunnel body Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel velocity ,like , If the results are consistent, it means that the numerical simulation analysis model's calculation results of the cultural relic cave structure are consistent with the measured results, and the numerical simulation analysis model's calculation results are accurate. If the numerical simulation analysis calculation results do not meet the above requirements, the model should be adjusted for the mesh size, the elastic modulus of the cultural relic cave material structure, and the parameters of the soil adjacent to the cultural relic cave until the simulation analysis results of the cultural relic cave are consistent with the theoretical calculation results.

9. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits as described in claim 8, characterized in that: In step S22, static and dynamic prediction analyses are performed based on the calibration model, including: extracting the brick and stone cultural relic cave body in the first... m+ The predicted horizontal displacement of the tunnel obtained from static analysis in one construction step Static analysis of the vertical displacement of the tunnel body Static analysis of tunnel stress Static analysis of tunnel strain , If the current support design does not meet the requirements for the subsequent protection of the brick and stone cultural relic cave, the support design should be adjusted; the brick and stone cultural relic cave should be extracted in the [missing information]. m+ Predicted horizontal displacement of the tunnel obtained from dynamic analysis in one construction step Dynamic analysis of the vertical displacement of the tunnel body Dynamic analysis of tunnel stress Dynamic analysis of tunnel strain Dynamic analysis of tunnel velocity ,like If the vibration of the current construction machinery and vehicles is determined to have a significant impact on the underground brick and stone cultural relic cave in the subsequent construction steps, the machinery and equipment, construction plan and support plan should be adjusted.

10. The method for assessing the stability of underground brick and stone cultural relic caves adjacent to building foundation pits according to claim 9, characterized in that: In step S3, the entire process of dismantling the temporary reinforcement measures is simulated. Monitoring and safety stability assessments of the brick and stone cultural relic cave are conducted during and after the dismantling process, including: S31. Safety and stability assessment of the cave structure during the removal of reinforcement measures: Simulation of the entire process of removing reinforcement measures, and extraction of brick and stone cultural relics from the cave structure in the [missing information]. k Horizontal displacement of the tunnel during each construction step Vertical displacement of the tunnel body Stress in the tunnel Strain of the tunnel ,in k The values ​​can be 1, 2, 3...; if If the current temporary reinforcement measures removal plan meets the requirements, it can be removed according to this plan. If it does not meet the above requirements, the temporary reinforcement measures removal plan should be adjusted and numerical simulation should be performed again. If it still does not meet the requirements, it is determined that the reinforcement measures are under too much stress and cannot be removed. S32. Monitoring after removal of temporary reinforcement measures: Continuous monitoring will be conducted after the removal of temporary reinforcement measures to obtain the horizontal displacement of the masonry tunnel during the excavation process of the foundation pit at each step of the removal of temporary reinforcement devices. and vertical displacement ; Safety and stability assessment of the cave after demolition: If temporary reinforcement measures are removed, the horizontal displacement of the brick and stone cultural relic cave will be continuously monitored during the subsequent period. And vertical displacement If the temporary reinforcement device is removed, the brick and stone cultural relic cave is determined to be in a safe and stable state, and the assessment is concluded.

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