A method and system for designing foundation pit retaining structure to prevent sudden water inrush risk

Abstract

The present invention discloses a design method and system for foundation pit retaining structure to prevent sudden water inrush, and relates to the field of foundation pit construction safety technology. Under complex geological conditions, the system can comprehensively obtain information on caves and fissures in karst strata through multi-scale comprehensive survey technology, generate an initial geological data set, and accurately divide the foundation pit area. Compared with traditional geophysical prospecting methods, the accuracy of geological forecasting is greatly improved. The system also accurately assesses underground risks by analyzing the degree of cave development, fissure filling conditions, soil bearing capacity, and groundwater level fluctuations, and monitors the deformation of the foundation pit in real time to promptly discover potential problems. In addition, the system grades the risk of sudden water inrush to generate different reinforced support retaining structures and densities, as well as drainage point settings, which can effectively deal with serious risks of sudden water inrush and prevent further damage to the foundation pit. In summary, the invention specifically and effectively reduces the probability of water inrush and collapse problems, thereby ensuring construction progress and safety.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation pit construction safety, and in particular to a design method and system for a foundation pit retaining structure to prevent sudden water inrush risks. Background Art

[0002] As the scale of subway construction continues to expand, the geological conditions encountered are becoming more and more complex, such as karst strata. The distribution area of ​​soluble rocks in China exceeds 3 million km, accounting for more than 1 / 3 of the country's land area, covering many provinces, autonomous regions, and municipalities directly under the central government. The karst strata in Yunnan, Guizhou, Guangxi, Sichuan, Hunan, and Hubei are particularly well developed. The construction of underground projects in karst areas has become an unavoidable problem in modern transportation construction.

[0003] Foundation pit construction is a key link in modern construction engineering, in which the design and management of retaining structures are crucial to the safety of foundation pit construction. Under complex geological conditions, especially in karst strata, foundation pit construction faces many challenges. At present, the engineering field mainly relies on safety management and advanced geological prediction (such as geophysical prospecting) to ensure the safety of subway station foundation pit and tunnel construction. However, due to the complex geological conditions in karst areas, traditional advanced geological prediction methods are often difficult to fully and accurately reveal the complex underground cave system and fracture network, and these methods have significant limitations in predicting water inrush risks. For example, although geophysical prospecting can provide preliminary information about underground structures, it is still difficult to obtain sufficient details about the specific development of caves. In addition, existing risk assessment and emergency response measures usually fail to respond to water inrush risks in a timely and comprehensive manner, resulting in serious problems such as sudden water inrush, collapse and structural instability in foundation pits, and it is impossible to take effective measures to deal with them quickly, thereby increasing construction safety risks. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method and system for designing a foundation pit retaining structure to prevent sudden water inrush risks, so as to solve the problems mentioned in the background technology.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a foundation pit retaining structure design system for preventing sudden water inrush risk, including a geological survey module, a real-time monitoring module, a data processing module, a dynamic design module, a cave reinforcement module and an emergency simulation control module;

[0006] The geological survey module is used to conduct geological surveys on the foundation pit area to be constructed, and obtain the cave distribution and fracture development information in the karst strata through multi-scale comprehensive survey technology, generate an initial geological data set, and divide the foundation pit area to be constructed into several sub-areas;

[0007] The real-time monitoring module is used to deploy monitoring points in several sub-areas during the simulation of foundation pit construction, and use the sensor network to monitor the groundwater level and the deformation parameters of the soil layer at the bottom of the foundation pit in real time to generate a monitoring data set;

[0008] The data processing module is used to screen, filter and denoise the initial geological data set and monitoring data set, and combine dimensionless processing technology to unify data units and establish a geological information database for karst stratum foundation pit construction;

[0009] The dynamic design module is used to extract relevant geological features based on the geological information database to calculate the cave development degree Fcd, soil bearing capacity Cz, crack filling condition Cxqk, groundwater level fluctuation value Sbz and construction pit deformation index Bxz, and obtain the cave risk coefficient Fx by associating the cave development degree Fcd with the crack filling condition Cxqk;

[0010] The groundwater level fluctuation value Sbz, soil bearing capacity Cz and construction pit deformation index Bxz are further correlated to obtain the water inrush risk index Tsq;

[0011] The cave reinforcement module is used to compare and analyze the cave risk factor Fx with the first risk threshold X1. If the cave risk factor Fx is higher than or equal to the first risk threshold X1, the area with caves or cracks in the foundation pit area is reinforced by high-strength grouting technology or self-healing material filling;

[0012] The emergency simulation control module is used to compare and analyze the water inrush risk index Tsq with the first water inrush risk threshold X11 and the second water inrush risk threshold X12, so as to simulate the automatic triggering of the emergency response mechanism when the water inrush risk occurs and provide corresponding emergency handling strategies.

[0013] Preferably, the method for obtaining the cave development degree Fcd comprises the following steps:

[0014] S11. Determine the key areas for geological exploration in the foundation pit area to be constructed and its surrounding areas, and arrange exploration points according to geological conditions and construction requirements;

[0015] S12. Detect and identify the location, shape and size of the caves in the key exploration area through geophysical exploration methods, including geological radar, seismic wave exploration, electrical exploration and drilling sampling. For the detected caves, record the volume V of the caves and the vertical depth d of the caves from the bottom of the foundation pit, and store them in the initial geological data set;

[0016] S13. Calculate the volume V of the jth cave by the following formula j :

[0017]

[0018] In the formula, r j is the equivalent radius of the jth cave;

[0019] And calculate the depth influence coefficient D of the jth cave j , the formula is as follows:

[0020]

[0021] Where, d j is the vertical distance from the top of the jth cave to the bottom of the foundation pit, and k is the depth attenuation coefficient;

[0022] The density sensor is used to collect the rock density ρ of the j-th cave, and the aspect ratio of the cave is obtained. The stability coefficient E of the j-th cave is calculated by the following formula: j , the formula is as follows:

[0023]

[0024] In the formula, ρ j is the rock density of the jth cave, Wd j is the width of the jth cave, Hd j is the height of the j-th cave, represents the aspect ratio of the cave, a1 and a2 are weight coefficients;

[0025] S14, the cave volume V of the jth cave j , Depth influence coefficient D j and stability factor E j After dimensionless processing, the cave development degree Fcd is calculated by the following formula:

[0026]

[0027] Where M is the total number of caves detected, A total is the total area of ​​the foundation pit area.

[0028] Preferably, the method for obtaining the soil bearing capacity Cz includes the following steps:

[0029] S21. In each sub-area, select multiple representative sampling points in the soil layer within the monitoring point, and use drilling sampling equipment to extract soil samples from different depths, and record the sampling depth and location;

[0030] S22, conducting laboratory tests on the extracted soil samples, determining the specific gravity γ of the soil layer and the internal friction angle φ of the soil body, and storing them in the initial geological data set;

[0031] S23. Calculate and obtain the soil bearing capacity Cz. The specific formula is:

[0032]

[0033] Cz=γ*D f *N q ;

[0034] Where N q is the soil bearing capacity coefficient, γ represents the weight of the soil layer, D f is the vertical distance between the bottom of the foundation and the ground surface, φ is the internal friction angle, 45° is a key angle in the foundation pressure distribution, 45° is used to deal with the shear failure surface of the soil. The change of angle makes the calculation more consistent with the actual stress distribution of the soil. Tanφ represents the tangent value of the internal friction angle of the soil, which determines the magnitude of the friction of the soil layer; Indicates the relationship between the principal stress direction and the fracture surface in the soil; e tan φ*π / 4 Amplify or weaken N through an exponential function q The value of depends on the internal friction angle φ and its purpose is to reflect how changes in soil strength affect the bearing capacity.

[0035] Preferably, the method for obtaining the fracture filling condition Cxqk comprises the following steps:

[0036] S31. Use high-precision geological radar or seismic exploration equipment to scan and record the location, direction and length of the fractures at the monitoring points in each sub-area;

[0037] S32. Extract samples from each crack by drilling or other sampling methods, measure and record the crack width Lfkd of the i-th crack i and the crack depth Lfsd of the i-th crack i ;

[0038] S33. The filling material sample extracted from the i-th crack is sent to the laboratory for analysis to determine the physical properties of the filling material, including: the compressive strength Kyqd of the i-th crack filling material i and the filling ratio Tcbl of the i-th crack filler i ;

[0039] S34, based on the data obtained in steps S32 and S33, the data are stored in the initial geological data set, and after dimensionless processing, the fracture filling condition Cxqk is calculated by the following formula:

[0040]

[0041] In the formula, m represents the number of cracks.

[0042] Preferably, the method for obtaining the groundwater level fluctuation value Sbz includes the following steps:

[0043] S41. During the simulated foundation pit construction process, groundwater level monitoring wells are set at the monitoring points in each sub-area, and water level monitoring is performed at a daily or hourly frequency, with an observation period of several days, weeks or the entire construction period;

[0044] S42. Use water level sensors in real time to regularly record the height of groundwater levels in underground water level monitoring wells. The water level height recorded in each observation is recorded as H i , and stored in the monitoring data set;

[0045] S43. After the observation period is over, all the collected water level data are processed and the average groundwater level H during the observation period is calculated using the following formula: avg :

[0046]

[0047] Where N is the total number of observations, H i represents the water level height of the i-th observation;

[0048] S44, each observation value H i The average groundwater level H avg The sum of squares of the deviations between the two is calculated, and the groundwater level fluctuation value Sbz in the form of standard deviation is calculated by the following formula:

[0049]

[0050] Where N is the total number of observations. The meaning of the formula is to judge the potential impact of groundwater level fluctuations on foundation pit safety based on the groundwater level fluctuation value Sbz.

[0051] Preferably, the construction pit deformation index Bxz is obtained as follows:

[0052] S51. During the simulation of foundation pit construction, a settlement meter, an inclinometer and a horizontal displacement sensor are installed at the monitoring point in each sub-area to record the foundation pit settlement data, inclination data and horizontal displacement data in real time and store them in a monitoring data set;

[0053] S52, processing all collected foundation pit settlement data, inclination data and horizontal displacement data, and calculating the average value of each monitoring point, as follows:

[0054] S521. Calculate the settlement CJ of each point at the bottom of the foundation pit i , and calculate the average settlement of all points

[0055]

[0056] Where t is the total number of settlement measurement points;

[0057] S522, calculate the inclination angle I of each point at the bottom of the foundation pit i , and find the average tilt angle of all points

[0058]

[0059] Where r is the total number of tilt measurement points;

[0060] S523. Calculate the horizontal displacement value D of each point at the bottom of the foundation pit h,i , and calculate the average horizontal displacement value of all points

[0061]

[0062] Where q is the total number of horizontal displacement measurement points;

[0063] S53, average settlement Average tilt angle and average horizontal displacement After dimensionless processing, the construction pit deformation index Bxz is calculated by the following related formula:

[0064]

[0065] Wherein, J1, J2 and J3 are weight coefficients.

[0066] Preferably, the dynamic design module includes a first associating unit and a second associating unit;

[0067] The first correlation unit is used to calculate the cave risk coefficient Fx by the following correlation formula after dimensionless processing of the cave development degree Fcd and the fracture filling condition Cxqk:

[0068]

[0069] In the formula, β1 and β2 represent the weight coefficients of cave development degree Fcd and fracture filling condition Cxqk, respectively, and R1 is the first correction constant;

[0070] The second correlation unit is used to calculate the water inrush risk index Tsq by non-dimensionalizing the groundwater level fluctuation value Sbz, the soil bearing capacity Cz and the construction pit deformation index Bxz through the following correlation formula:

[0071]

[0072] Where β3, β4 and β5 represent the weight coefficients of groundwater level fluctuation value Sbz, construction pit deformation index Bxz and soil bearing capacity Cz respectively, and R2 is the second correction constant.

[0073] Preferably, the cave reinforcement module includes a first evaluation unit and a first strategy unit;

[0074] The first assessment unit is used to preset a first risk threshold value X1, and compare and analyze the cave risk coefficient Fx with the first risk threshold value X1, and obtain a first assessment result including:

[0075] When the cave risk coefficient Fx ≥ the first risk threshold X1, it means that the cave risk in the sub-area is abnormal and there is a safety risk in the foundation pit construction. The first filling instruction is generated through the first strategy unit, including reinforcing the area with caves or cracks in the foundation pit area, filling the gaps and caves with self-healing polymers or grouting technology, and setting a support point every 8 meters in the sub-area. The depth of the enclosure structure in the support point is 1.1 times the depth of the foundation pit in the sub-area;

[0076] When the cave risk coefficient Fx is less than the first risk threshold X1, it means that the cave risk in the sub-area is normal and continuous monitoring is required.

[0077] Preferably, the emergency simulation control module further includes a second evaluation unit and a second strategy unit;

[0078] The second evaluation unit is used to preset a first water inrush risk threshold value X11 and a second water inrush risk threshold value X12, and the first water inrush risk threshold value X11 is less than the second water inrush risk threshold value X12;

[0079] The water inrush risk index Tsq is compared and analyzed with the first water inrush risk threshold X11 and the second water inrush risk threshold X12, and the second assessment results are obtained, including:

[0080] When the water inrush risk index Tsq is less than the first water inrush risk threshold X11, it means: there is no water inrush risk, and normal construction operations and continuous monitoring are continued;

[0081] When the first water inrush risk threshold X11≤water inrush risk index Tsq≤second water inrush risk threshold X12, it indicates that there is a first water inrush risk, and the second strategy unit generates a first drainage reinforcement instruction, including setting up a drainage system, setting at least two drainage points for every 100 square meters of foundation pit, starting the foundation drainage system, including vertical drainage wells and horizontal drainage pipes, draining water once every hour to reduce 30% of the current water level, and setting a support point every 5 meters in the sub-area, and the depth of the enclosure structure in the support point is 1.2 times the depth of the foundation pit in the sub-area;

[0082] When the water inrush risk index Tsq is greater than the second water inrush risk threshold X12, it means: there is a second water inrush risk, which is higher than the first risk level and has a high severity. The second strategy unit generates a second drainage reinforcement instruction: including: setting up a drainage system, with at least two drainage points for every 80 square meters of foundation pit, starting the drainage system, including backup drainage equipment and enhanced drainage facilities, draining water every 15-30 minutes to reduce the water level by 50% and carry out emergency reinforcement of the retaining structure, including compacting the soil wall with a vibrating compactor and mixing the soil with a binder to increase the soil wall density by 30%; and setting a support point every 3 meters in the sub-area, and the depth of the retaining structure at the support point is 1.3 times the depth of the sub-area foundation pit; and setting a 15-25% waterproof layer on the outside of the retaining structure.

[0083] A method for designing a foundation pit retaining structure to prevent sudden water inrush risk comprises the following steps:

[0084] Step 1: Conduct geological survey on the area to be constructed, and obtain information on cave distribution and fissure development in the karst strata through multi-scale comprehensive survey technology, generate an initial geological data set, and divide the area to be constructed into several sub-areas;

[0085] Step 2: During the simulated foundation pit construction process, monitoring points are arranged in several sub-areas, and the groundwater level and the deformation parameters of the soil layer at the bottom of the foundation pit are monitored in real time using a sensor network to generate a monitoring data set;

[0086] Step 3: Screen, filter and denoise the initial geological data set and monitoring data set, and combine dimensionless processing technology to unify data units and establish a geological information database for karst stratum foundation pit construction;

[0087] Step 4: Based on the geological information database, extract relevant geological features to calculate the cave development degree Fcd, soil bearing capacity Cz, crack filling condition Cxqk, groundwater level fluctuation value Sbz and construction pit deformation index Bxz, and obtain the cave risk coefficient Fx by correlating the cave development degree Fcd with the crack filling condition Cxqk;

[0088] The groundwater level fluctuation value Sbz, soil bearing capacity Cz and construction pit deformation index Bxz are further correlated to obtain the water inrush risk index Tsq;

[0089] Step 5: Compare and analyze the cave risk factor Fx with the first risk threshold X1. If the cave risk factor Fx is higher than or equal to the first risk threshold X1, reinforce the area with caves or cracks in the foundation pit area by using high-strength grouting technology or filling with self-healing materials.

[0090] Step six: compare and analyze the water inrush risk index Tsq with the first water inrush risk threshold X11 and the second water inrush risk threshold X12 respectively, so as to simulate the automatic triggering of the emergency response mechanism when the water inrush risk occurs and provide corresponding emergency handling strategies.

[0091] The present invention provides a method and system for designing a foundation pit retaining structure to prevent sudden water inrush risks. It has the following beneficial effects:

[0092] (1) This foundation pit retaining structure design system for preventing sudden water inrush has significantly improved the safety and management efficiency of foundation pit construction under complex geological conditions, overcoming many limitations of existing technologies. Through multi-scale comprehensive survey technology, it is possible to comprehensively obtain information on the development of caves and fissures in karst strata, generate initial geological data sets, and accurately divide the foundation pit area. Compared with traditional geophysical methods, this method can reveal the complex underground cave system and fracture network in more detail, improving the accuracy of geological forecasts.

[0093] (2) This system for designing foundation pit retaining structures to prevent sudden water inrush can accurately identify and assess the risks of underground caves and fissures through in-depth analysis of the degree of cave development Fcd and the filling status of fissures Cxqk. This comprehensive risk assessment helps to understand the complex underground conditions in advance and avoids the problem of insufficient understanding of underground structures in traditional methods. The calculation of the soil bearing capacity Cz provides detailed bearing capacity information of the foundation pit soil layer, which can effectively evaluate the stability of the soil layer and ensure that the soil will not deform or collapse due to insufficient bearing during construction. This detailed calculation helps to improve the safety and stability of the foundation pit design. The monitoring of the groundwater level fluctuation value Sbz can track the changes in the groundwater level in real time and promptly detect potential risks of sudden water inrush. This real-time data helps to quickly adjust construction measures and reduce safety hazards caused by sudden water inrush. The construction foundation pit deformation index Bxz can dynamically evaluate the deformation of the foundation pit during the construction process, promptly detect and deal with problems such as settlement, tilt and horizontal displacement, thereby effectively preventing the instability of the foundation pit structure.

[0094] (3) This method provides corresponding reinforcement and drainage measures for different risk thresholds through an automatically triggered emergency response strategy. Compared with traditional methods, this method can quickly respond to sudden water inrush and soil deformation problems, significantly reduce possible emergencies during construction, improve the safety and stability of foundation pit construction, and effectively prevent serious problems such as water inrush, collapse and structural instability. Through these measures, the construction team can more calmly deal with various risks under complex geological conditions and ensure construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 It is a schematic diagram of a flow chart of a system for designing a foundation pit retaining structure to prevent sudden water inrush risks according to the present invention;

[0096] Figure 2 The present invention is a schematic diagram of the steps of a method for designing a foundation pit retaining structure to prevent sudden water inrush risks. DETAILED DESCRIPTION

[0097] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0098] Example 1

[0099] See also Figure 1 , the present invention provides a foundation pit retaining structure design system for preventing sudden water inrush risks, including a geological survey module, a real-time monitoring module, a data processing module, a dynamic design module, a cave reinforcement module and an emergency simulation control module;

[0100] The geological survey module is used to conduct geological surveys in the area where the foundation pit is to be constructed. Through multi-scale comprehensive survey technology, it obtains information on the distribution of caves and fissure development in the karst strata, generates an initial geological data set, and divides the area where the foundation pit is to be constructed into several sub-areas. This process can provide a detailed understanding of the complex underground karst structure, which is helpful for subsequent design and monitoring work.

[0101] The real-time monitoring module is used to deploy monitoring points in several sub-areas during the simulation of foundation pit construction, and use the sensor network to monitor the groundwater level and the deformation parameters of the soil layer at the bottom of the foundation pit in real time to generate a monitoring data set; monitoring points are deployed in multiple sub-areas, and the sensor network is used to monitor the groundwater level and the deformation parameters of the soil layer at the bottom of the foundation pit in real time. The generated monitoring data set includes water level changes and soil deformation information, providing basic data for timely detection of potential risks.

[0102] The data processing module is used to screen, filter and denoise the initial geological data set and monitoring data set, and combine dimensionless processing technology to unify data units and establish a geological information database for karst stratum foundation pit construction; this process ensures the accuracy and availability of the data and provides reliable basic data for dynamic design.

[0103] The dynamic design module is used to extract relevant geological features based on the geological information database to calculate the cave development degree Fcd, soil bearing capacity Cz, crack filling condition Cxqk, groundwater level fluctuation value Sbz and construction pit deformation index Bxz, and obtain the cave risk coefficient Fx by associating the cave development degree Fcd with the crack filling condition Cxqk;

[0104] The groundwater level fluctuation value Sbz, soil bearing capacity Cz and construction pit deformation index Bxz are further correlated to obtain the water inrush risk index Tsq;

[0105] The cave reinforcement module is used to compare and analyze the cave risk factor Fx with the first risk threshold X1. If the cave risk factor Fx is higher than or equal to the first risk threshold X1, the area with caves or cracks in the foundation pit area is reinforced by high-strength grouting technology or self-healing material filling;

[0106] The emergency simulation control module is used to compare and analyze the water inrush risk index Tsq with the first water inrush risk threshold X11 and the second water inrush risk threshold X12, so as to simulate the automatic triggering of the emergency response mechanism when the water inrush risk occurs and provide corresponding emergency handling strategies.

[0107] In this embodiment, by integrating geological surveys and real-time monitoring data, the risk of water inrush is accurately assessed, potential hidden dangers are identified in advance, and effective reinforcement measures are formulated to significantly improve the safety of foundation pit construction. The dynamic design module is used for detailed risk analysis, which can accurately calculate the cave risk factor Fx and the water inrush risk index Tsq, providing a scientific basis for construction management and emergency response. The implementation of this system helps to provide all-round safety protection, improve construction efficiency, and effectively respond to the risk of sudden water inrush when carrying out subway foundation pit construction in karst areas.

[0108] Example 2

[0109] The method for obtaining the cave development degree Fcd includes the following steps:

[0110] S11. Determine the key areas for geological exploration in the foundation pit area to be constructed and its surrounding areas, and arrange exploration points according to geological conditions and construction requirements;

[0111] S12. Detect and identify the location, shape and size of the caves in the key exploration area through geophysical exploration methods, including geological radar, seismic wave exploration, electrical exploration and drilling sampling. For the detected caves, record the volume V of the caves and the vertical depth d of the caves from the bottom of the foundation pit, and store them in the initial geological data set;

[0112] S13. Calculate the volume V of the jth cave by the following formula j :

[0113]

[0114] In the formula, r j is the equivalent radius of the jth cave;

[0115] And calculate the depth influence coefficient D of the jth cave j , the formula is as follows:

[0116]

[0117] Where, d j is the vertical distance from the top of the jth cave to the bottom of the foundation pit, and k is the depth attenuation coefficient;

[0118] The density sensor is used to collect the rock density ρ of the j-th cave, and the aspect ratio of the cave is obtained. The stability coefficient E of the j-th cave is calculated by the following formula: j , the formula is as follows:

[0119]

[0120] In the formula, ρ j is the rock density of the jth cave, Wd j is the width of the jth cave, Hd j is the height of the j-th cave, Indicates the aspect ratio of the cave, a1 and a2 are weight coefficients; they are adjusted and set by the user, and the sum of the weight coefficients is 1, and the stability coefficient E j Taking into account factors such as rock density and aspect ratio, the structural stability of the cave can be fully evaluated, which helps to determine whether the cave needs reinforcement.

[0121] S14, the cave volume V of the jth cave j , Depth influence coefficient D j and stability factor E j After dimensionless processing, the cave development degree Fcd is calculated by the following formula:

[0122]

[0123] Where M is the total number of caves detected, A total is the total area of ​​the foundation pit area.

[0124] The cave development degree Fcd obtained by comprehensive calculation of various indicators can provide a dimensionless value that reflects the development of caves in the entire foundation pit area. This value helps to comprehensively evaluate the cave risks in the area and is used to guide foundation pit construction design and reinforcement measures, thereby effectively improving construction safety and stability.

[0125] Example 3

[0126] The method for obtaining the soil bearing capacity Cz includes the following steps:

[0127] S21. In each sub-area, select multiple representative sampling points in the soil layer within the monitoring point, and use drilling sampling equipment to extract soil samples from different depths, and record the sampling depth and location;

[0128] S22, conducting laboratory tests on the extracted soil samples, determining the specific gravity γ of the soil layer and the internal friction angle φ of the soil body, and storing them in the initial geological data set;

[0129] S23. Calculate and obtain the soil bearing capacity Cz. The specific formula is:

[0130]

[0131] Cz=γ*D f *N q ;

[0132] Where N q is the soil bearing capacity coefficient, γ represents the weight of the soil layer, D f is the vertical distance between the bottom of the foundation and the ground surface, φ is the internal friction angle, 45° is a key angle in the foundation pressure distribution, 45° is used to deal with the shear failure surface of the soil. The change of angle makes the calculation more consistent with the actual stress distribution of the soil. Tanφ represents the tangent value of the internal friction angle of the soil, which determines the magnitude of the friction of the soil layer; Indicates the relationship between the principal stress direction and the fracture surface in the soil; e tan φ*π / 4 Amplify or weaken N through an exponential function q The value of depends on the internal friction angle φ and its purpose is to reflect how changes in soil strength affect the bearing capacity.

[0133] In this embodiment, by comprehensively considering the gravity, vertical distance, internal friction angle and their influence on bearing capacity, the bearing capacity of the soil layer can be accurately evaluated. The soil layer bearing capacity Cz helps to design a safer foundation pit retaining structure and reduce the structural instability and safety hazards that may occur during the construction process. Through real-time monitoring and data updating, the bearing capacity calculation results can be dynamically adjusted to adapt to changes in the actual construction process, further improving the safety and reliability of the construction.

[0134] Example 4

[0135] The method for obtaining the fracture filling condition Cxqk includes the following steps:

[0136] S31. Use high-precision geological radar or seismic exploration equipment to scan and record the location, direction and length of the fractures at the monitoring points in each sub-area;

[0137] S32. Extract samples from each crack by drilling or other sampling methods, measure and record the crack width Lfkd of the i-th crack i and the crack depth Lfsd of the i-th crack i ;

[0138] S33. The filling material sample extracted from the i-th crack is sent to the laboratory for analysis to determine the physical properties of the filling material, including: the compressive strength Kyqd of the i-th crack filling material i and the filling ratio Tcbl of the i-th crack filler i ;

[0139] S34, based on the data obtained in steps S32 and S33, the data are stored in the initial geological data set, and after dimensionless processing, the fracture filling condition Cxqk is calculated by the following formula:

[0140]

[0141] In the formula, m represents the number of cracks.

[0142] In this embodiment, the spatial distribution of the cracks can be fully understood through high-precision equipment scanning. This helps to understand the distribution density and scale of the cracks and provide basic data for subsequent filling material analysis. Accurately recording the location and direction of the cracks can help identify potential risk areas. By comprehensively considering the filling ratio and compressive strength, calculating the crack filling condition Cxqk can comprehensively evaluate the performance of the filling material in the actual project. It can guide the selection of more suitable filling materials. This comprehensive evaluation can more accurately reflect the effectiveness and stability of the filling material.

[0143] Example 5

[0144] The method for obtaining the groundwater level fluctuation value Sbz includes the following steps:

[0145] S41. During the simulated foundation pit construction process, groundwater level monitoring wells are set at the monitoring points in each sub-area, and water level monitoring is performed at a daily or hourly frequency, with an observation period of several days, weeks or the entire construction period;

[0146] S42. Use water level sensors in real time to regularly record the height of groundwater levels in underground water level monitoring wells. The water level height recorded in each observation is recorded as H i , and stored in the monitoring data set;

[0147] S43. After the observation period is over, all the collected water level data are processed and the average groundwater level H during the observation period is calculated using the following formula: avg :

[0148]

[0149] Where N is the total number of observations, H i represents the water level height of the i-th observation;

[0150] S44, each observation value H iThe average groundwater level H avg The sum of squares of the deviations between the two is calculated, and the groundwater level fluctuation value Sbz in the form of standard deviation is calculated by the following formula:

[0151]

[0152] Where N is the total number of observations. The meaning of the formula is to judge the potential impact of groundwater level fluctuations on foundation pit safety based on the groundwater level fluctuation value Sbz.

[0153] In this embodiment, by calculating the standard deviation of the groundwater level, the fluctuation of the groundwater level can be accurately evaluated. This helps to understand the range of changes in the groundwater level and detect abnormal fluctuations in a timely manner, thereby predicting and preventing risks that may occur during foundation pit construction. The groundwater level fluctuation value Sbz in the form of standard deviation can reflect the severity of groundwater level fluctuations. Large fluctuation values ​​may indicate that the groundwater level fluctuates violently, increasing the risk of foundation pit construction. This information can be used to adjust the construction plan or take additional safety measures. Through real-time monitoring and analysis of groundwater level fluctuations, groundwater level changes that may affect the stability of the foundation pit can be identified in advance, helping engineers take appropriate countermeasures to ensure the safety of foundation pit construction.

[0154] Example 6

[0155] The method for obtaining the construction pit deformation index Bxz is as follows:

[0156] S51. During the simulation of foundation pit construction, a settlement meter, an inclinometer and a horizontal displacement sensor are installed at the monitoring point in each sub-area to record the foundation pit settlement data, inclination data and horizontal displacement data in real time and store them in a monitoring data set;

[0157] S52, processing all collected foundation pit settlement data, inclination data and horizontal displacement data, and calculating the average value of each monitoring point; the details are as follows:

[0158] S521. Calculate the settlement CJ of each point at the bottom of the foundation pit i , and calculate the average settlement of all points

[0159]

[0160] Where t is the total number of settlement measurement points;

[0161] S522, calculate the inclination angle I of each point at the bottom of the foundation pit i , and find the average tilt angle of all points

[0162]

[0163] Where r is the total number of tilt measurement points;

[0164] S523. Calculate the horizontal displacement value D of each point at the bottom of the foundation pit h,i , and calculate the average horizontal displacement value of all points

[0165]

[0166] Where q is the total number of horizontal displacement measurement points;

[0167] S53, average settlement Average tilt angle and average horizontal displacement After dimensionless processing, the construction pit deformation index Bxz is calculated by the following related formula:

[0168]

[0169] Wherein, J1, J2 and J3 are weight coefficients, which are adjusted and set by the user, and the sum of the weight coefficients is 1.

[0170] In this embodiment, by simulating the deformation of the foundation pit during the construction process and comprehensively considering the settlement, inclination angle and horizontal displacement, the deformation of the foundation pit can be comprehensively evaluated and the overall stability of the foundation pit during the construction process can be accurately reflected. According to the changing trend of the construction foundation pit deformation index Bxz, the construction plan and management measures can be adjusted to control and reduce the deformation of the foundation pit and improve the construction safety and engineering quality.

[0171] Example 7

[0172] Please refer to Figure 1 , the dynamic design module includes a first associated unit and a second associated unit;

[0173] The first correlation unit is used to calculate the cave risk coefficient Fx by the following correlation formula after dimensionless processing of the cave development degree Fcd and the fracture filling condition Cxqk:

[0174]

[0175] In the formula, β1 and β2 represent the weight coefficients of the cave development degree Fcd and the fracture filling condition Cxqk, respectively, which are adjusted and set by the user, and the sum of the weight coefficients is 1, and R1 is the first correction constant; the cave risk coefficient Fx comprehensively considers the cave development degree and the fracture filling condition, and ensures the uniformity of the data through dimensionless processing, making the risk assessment more accurate and objective. The calculated cave risk coefficient can provide a basis for the design of foundation pit retaining structure, help engineers optimize the design plan, and reduce potential safety hazards caused by cave risks.

[0176] The second correlation unit is used to calculate the water inrush risk index Tsq by non-dimensionalizing the groundwater level fluctuation value Sbz, the soil bearing capacity Cz and the construction pit deformation index Bxz through the following correlation formula:

[0177]

[0178] In the formula, β3, β4 and β5 represent the weight coefficients of groundwater level fluctuation value Sbz, construction foundation pit deformation index Bxz and soil bearing capacity Cz respectively, which are adjusted and set by the user, and the sum of the weight coefficients is 1, and R2 is the second correction constant. The water inrush risk index Tsq combines the factors of groundwater level fluctuation, soil bearing capacity and foundation pit deformation, providing a comprehensive water inrush risk assessment, which can more accurately reflect the water inrush risk that may be faced during the construction process. Through the water inrush risk index, high-risk areas can be effectively identified, emergency response plans can be optimized, and effective measures can be taken quickly when a water inrush event occurs to reduce the impact on construction progress and safety.

[0179] The cave reinforcement module includes a first assessment unit and a first strategy unit;

[0180] The first assessment unit is used to preset a first risk threshold value X1, and compare and analyze the cave risk coefficient Fx with the first risk threshold value X1, and obtain a first assessment result including:

[0181] When the cave risk coefficient Fx ≥ the first risk threshold X1, it means: the cave risk in the sub-area is abnormal, there is a safety risk in the foundation pit construction, and an alarm message is sent, and the first filling instruction is generated through the first strategy unit, including reinforcing the area with caves or cracks in the foundation pit area, using self-healing polymers or grouting technology to fill gaps and caves, and setting a support point every 8 meters in the sub-area, which can effectively enhance the structural stability of the foundation pit sub-area and reduce the impact of caves and cracks on construction. The depth of the enclosure structure in the support point is 1.1 times the depth of the foundation pit in the sub-area; ensuring the effectiveness and safety of the reinforcement measures. Clear reinforcement strategies and support point setting specifications can effectively reduce unexpected situations caused by caves and cracks during construction, thereby avoiding delays in construction progress and improving the overall progress and efficiency of the project.

[0182] When the cave risk coefficient Fx is less than the first risk threshold X1, it means that the cave risk in the sub-area is normal and continuous monitoring is required.

[0183] The first assessment unit can accurately identify sub-areas with abnormal risks by comparing the cave risk factor Fx with the preset first risk threshold X1, so as to take appropriate reinforcement measures in potential high-risk areas. Through comparative analysis, resources and equipment can be reasonably allocated, high-risk areas can be prioritized, resource waste can be avoided, and the efficiency of construction safety management can be improved.

[0184] The emergency simulation control module also includes a second evaluation unit and a second strategy unit;

[0185] The second evaluation unit is used to preset a first water inrush risk threshold value X11 and a second water inrush risk threshold value X12, and the first water inrush risk threshold value X11 is less than the second water inrush risk threshold value X12;

[0186] The water inrush risk index Tsq is compared and analyzed with the first water inrush risk threshold X11 and the second water inrush risk threshold X12, and the second assessment results are obtained, including:

[0187] When the water inrush risk index Tsq is less than the first water inrush risk threshold X11, it means: there is no water inrush risk, and normal construction operations and continuous monitoring are continued;

[0188] When the first water inrush risk threshold X11≤water inrush risk index Tsq≤second water inrush risk threshold X12, it indicates that there is a first water inrush risk, and the second strategy unit generates a first drainage reinforcement instruction, including setting up a drainage system, setting at least two drainage points for every 100 square meters of foundation pit, starting the foundation drainage system, including vertical drainage wells and horizontal drainage pipes, draining water once every hour to reduce 30% of the current water level, and setting a support point every 5 meters in the sub-area, and the depth of the enclosure structure in the support point is 1.2 times the depth of the foundation pit in the sub-area;

[0189] When the water inrush risk index Tsq is greater than the second water inrush risk threshold X12, it means: there is a second water inrush risk, which is higher than the first risk level and has a high severity. The second strategy unit generates a second drainage reinforcement instruction: including: setting up a drainage system, with at least two drainage points for every 80 square meters of foundation pit, starting the drainage system, including backup drainage equipment and enhanced drainage facilities, draining water every 15-30 minutes to reduce the water level by 50% and carry out emergency reinforcement of the retaining structure, including compacting the soil wall with a vibrating compactor and mixing the soil with a binder to increase the soil wall density by 30%; and setting a support point every 3 meters in the sub-area, and the depth of the retaining structure at the support point is 1.3 times the depth of the sub-area foundation pit; and setting a 15-25% waterproof layer on the outside of the retaining structure.

[0190] In this embodiment, the second assessment unit can classify the water inrush risk by comparing the water inrush risk index Tsq with two different risk thresholds X11 and X12. This classification can more accurately identify the severity of the water inrush risk, so as to take more targeted emergency measures. The clear risk threshold setting enables different levels of water inrush risks to be responded to in a timely and effective manner. For example, when the water inrush risk index Tsq is between the first water inrush risk threshold and the second water inrush risk threshold, the system will initiate relatively basic drainage and reinforcement measures; when the water inrush risk index Tsq exceeds the second water inrush risk threshold, higher-level and more urgent emergency measures will be initiated to ensure construction safety. Through comparative analysis and risk grading, emergency management can be optimized, so that the construction team can adjust the emergency response strategy according to the actual risk situation, avoid excessive response and waste of resources, and improve the efficiency of emergency handling.

[0191] The second strategy unit has the following beneficial effects:

[0192] Timely and effective drainage measures: The first drainage reinforcement instruction includes setting up drainage systems and support point setting specifications to ensure that the water level can be effectively removed and the safety of the foundation pit can be ensured in the event of water inrush risk. By setting up two drainage points every 100 square meters and draining water frequently, the water level can be quickly lowered and the risk of water inrush can be reduced.

[0193] Strengthening the supporting structure: In the drainage reinforcement measures for the first risk of water inrush, a supporting point is set up every 5 meters and the retaining structure of the supporting point is deepened, which can significantly enhance the stability of the foundation pit and effectively deal with the structural risks caused by water inrush.

[0194] Advanced measures to deal with severe water inrush risks: When the water inrush risk index exceeds the second risk threshold, the second drainage reinforcement instruction provides more comprehensive emergency measures, including more intensive drainage point settings, more frequent drainage, the use of backup drainage equipment, and emergency reinforcement measures such as soil wall compaction and density increase, which can effectively deal with severe water inrush risks.

[0195] Improve construction safety and stability: High-level drainage and reinforcement measures, including the use of vibratory compactors and binders, can significantly improve the density of the soil wall and the stability of the supporting structure, further improving construction safety. The installation of a waterproof layer helps reduce water infiltration and prevent further damage to the foundation pit.

[0196] Effectively control the spread of risks: Through comprehensive emergency measures, when the risk of water inrush occurs, the risk can be quickly controlled and mitigated to avoid the spread and aggravation of the risk, thereby ensuring the construction progress and safety.

[0197] Example 8

[0198] See also Figure 2 A method for designing a foundation pit retaining structure to prevent sudden water inrush risk comprises the following steps:

[0199] Step 1: Conduct geological survey on the area to be constructed, and obtain information on cave distribution and fissure development in the karst strata through multi-scale comprehensive survey technology, generate an initial geological data set, and divide the area to be constructed into several sub-areas;

[0200] Step 2: During the simulation of foundation pit construction, monitoring points are arranged in several sub-areas, and the groundwater level and deformation parameters of the soil layer at the bottom of the foundation pit are monitored in real time using a sensor network to generate a monitoring data set;

[0201] Step 3: Screen, filter and denoise the initial geological data set and monitoring data set, and combine dimensionless processing technology to unify data units and establish a geological information database for karst stratum foundation pit construction;

[0202] Step 4: Based on the geological information database, extract relevant geological features to calculate the cave development degree Fcd, soil bearing capacity Cz, crack filling condition Cxqk, groundwater level fluctuation value Sbz and construction pit deformation index Bxz, and obtain the cave risk coefficient Fx by correlating the cave development degree Fcd with the crack filling condition Cxqk;

[0203] The groundwater level fluctuation value Sbz, soil bearing capacity Cz and construction pit deformation index Bxz are further correlated to obtain the water inrush risk index Tsq;

[0204] Step 5: Compare and analyze the cave risk factor Fx with the first risk threshold X1. If the cave risk factor Fx is higher than or equal to the first risk threshold X1, reinforce the area with caves or cracks in the foundation pit area by using high-strength grouting technology or filling with self-healing materials.

[0205] Step six: compare and analyze the water inrush risk index Tsq with the first water inrush risk threshold X11 and the second water inrush risk threshold X12 respectively, so as to simulate the automatic triggering of the emergency response mechanism when the water inrush risk occurs and provide corresponding emergency handling strategies.

[0206] The threshold is set to facilitate comparison. The size of the threshold depends on the amount of sample data and the number of bases set by technicians in this field for each group of sample data; as long as it does not affect the proportional relationship between the parameter and the quantized value.

[0207] The above formulas are obtained by collecting a large amount of data for software simulation and selecting a formula that is close to the actual value. The coefficients in the formula are set by technical personnel in this field according to actual conditions. The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited to this. Any technical personnel familiar with the technical field within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, make equivalent replacement or change, which should be covered within the protection scope of the present invention.

Claims

1. A foundation pit retaining structure design system for preventing sudden water inrush risk, characterized by: It includes geological survey module, real-time monitoring module, data processing module, dynamic design module, cave reinforcement module and emergency simulation control module; The geological survey module is used to conduct geological survey on the foundation pit area to be constructed, and obtain the cave distribution and fissure development information in the karst stratum through multi-scale comprehensive survey technology, generate an initial geological data set, and divide the foundation pit area to be constructed into several sub-areas; The real-time monitoring module is used to deploy monitoring points in several sub-areas during the simulation of foundation pit construction, and use the sensor network to monitor the groundwater level and the deformation parameters of the soil layer at the bottom of the foundation pit in real time to generate a monitoring data set; The data processing module is used to screen, filter and denoise the initial geological data set and the monitoring data set, and unify the data units by combining dimensionless processing technology to establish a geological information database for karst stratum foundation pit construction; The dynamic design module is used to extract relevant geological features based on the geological information database to calculate the cave development degree Fcd, soil layer bearing capacity Cz, crack filling condition Cxqk, groundwater level fluctuation value Sbz and construction pit deformation index Bxz, and obtain the cave risk coefficient Fx by associating the cave development degree Fcd with the crack filling condition Cxqk; Further correlating the groundwater level fluctuation value Sbz, the soil layer bearing capacity Cz and the construction pit deformation index Bxz to obtain a water inrush risk index Tsq; The karst cave reinforcement module is used to compare and analyze the karst cave risk coefficient Fx with the first risk threshold X1. If the karst cave risk coefficient Fx is higher than or equal to the first risk threshold X1, the area with karst caves or cracks in the foundation pit area is reinforced by high-strength grouting technology or self-healing material filling; The emergency simulation control module is used to compare and analyze the water inrush risk index Tsq with the first water inrush risk threshold X11 and the second water inrush risk threshold X12, so as to simulate the automatic triggering of the emergency response mechanism when the water inrush risk occurs and provide a corresponding emergency handling strategy.

2. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The method for obtaining the cave development degree Fcd comprises the following steps: S11. Determine the key areas for geological exploration in the foundation pit area to be constructed and its surrounding areas, and arrange exploration points according to geological conditions and construction requirements; S12. Detect and identify the location, shape and size of the caves in the key exploration area through geophysical exploration methods, including geological radar, seismic wave exploration, electrical exploration and drilling sampling. For the detected caves, record the volume V of the caves and the vertical depth d of the caves from the bottom of the foundation pit, and store them in the initial geological data set; S13. Calculate the volume V of the jth cave by the following formula j : In the formula, r j is the equivalent radius of the jth cave; And calculate the depth influence coefficient D of the jth cave j , the formula is as follows: Where, d j is the vertical distance from the top of the jth cave to the bottom of the foundation pit, and k is the depth attenuation coefficient; The density sensor is used to collect the rock density ρ of the j-th cave, and the aspect ratio of the cave is obtained. The stability coefficient E of the j-th cave is calculated by the following formula: j , the formula is as follows: In the formula, ρ j is the rock density of the jth cave, Wd j is the width of the jth cave, Hd j is the height of the j-th cave, represents the aspect ratio of the cave, a1 and a2 are weight coefficients; S14, the volume V of the j-th cave j , Depth influence coefficient D j and stability factor E j After dimensionless processing, the cave development degree Fcd is calculated by the following formula: Where M is the total number of caves detected, A total is the total area of ​​the foundation pit area.

3. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The method for obtaining the soil bearing capacity Cz comprises the following steps: S21. In each sub-area, select multiple representative sampling points in the soil layer within the monitoring point, and use drilling sampling equipment to extract soil samples from different depths, and record the sampling depth and location; S22, conducting laboratory tests on the extracted soil samples, determining the specific gravity γ of the soil layer and the internal friction angle φ of the soil body, and storing them in the initial geological data set; S23. Calculate and obtain the soil bearing capacity Cz. The specific formula is: Cz=γ*D f *N q ; Where N q is the soil bearing capacity coefficient, γ represents the weight of the soil layer, D f is the vertical distance between the bottom of the foundation and the ground surface, φ is the internal friction angle, 45° is a key angle in the foundation pressure distribution, 45° is used to deal with the shear failure surface of the soil. The change of angle makes the calculation more consistent with the actual stress distribution of the soil. Tanφ represents the tangent value of the internal friction angle of the soil, which determines the magnitude of the friction of the soil layer; Indicates the relationship between the principal stress direction and the fracture surface in the soil; e tanφ*π / 4 Amplify or weaken N through an exponential function q The value of depends on the internal friction angle φ and its purpose is to reflect how changes in soil strength affect the bearing capacity.

4. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The method for obtaining the fracture filling condition Cxqk comprises the following steps: S31. Use high-precision geological radar or seismic exploration equipment to scan and record the location, direction and length of the fractures at the monitoring points in each sub-area; S32. Extract samples from each crack by drilling or other sampling methods, measure and record the crack width Lfkd of the i-th crack i and the crack depth Lfsd of the i-th crack i ; S33. The filling material sample extracted from the i-th crack is sent to the laboratory for analysis to determine the physical properties of the filling material, including: the compressive strength Kyqd of the i-th crack filling material i and the filling ratio Tcbl of the i-th crack filler i ; S34, based on the data obtained in steps S32 and S33, the data are stored in the initial geological data set, and after dimensionless processing, the fracture filling condition Cxqk is calculated by the following formula: In the formula, m represents the number of cracks.

5. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The method for obtaining the groundwater level fluctuation value Sbz comprises the following steps: S41. During the simulated foundation pit construction process, groundwater level monitoring wells are set at the monitoring points in each sub-area, and water level monitoring is performed at a daily or hourly frequency, with an observation period of several days, weeks or the entire construction period; S42. Use water level sensors in real time to regularly record the height of groundwater levels in underground water level monitoring wells. The water level height recorded in each observation is recorded as H i , and stored in the monitoring data set; S43. After the observation period is over, all the collected water level data are processed and the average groundwater level H during the observation period is calculated using the following formula: avg : Where N is the total number of observations, H i represents the water level height of the i-th observation; S44, each observation value H i The average groundwater level H avg The sum of squares of the deviations between the two is calculated, and the groundwater level fluctuation value Sbz in the form of standard deviation is calculated by the following formula: Where N is the total number of observations. The meaning of the formula is to judge the potential impact of groundwater level fluctuations on foundation pit safety based on the groundwater level fluctuation value Sbz.

6. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The method for obtaining the construction pit deformation index Bxz is as follows: S51. During the simulation of foundation pit construction, a settlement meter, an inclinometer and a horizontal displacement sensor are installed at the monitoring point in each sub-area to record the foundation pit settlement data, inclination data and horizontal displacement data in real time and store them in a monitoring data set; S52, processing all collected foundation pit settlement data, inclination data and horizontal displacement data, and calculating the average value of each monitoring point, as follows: S521. Calculate the settlement CJ of each point at the bottom of the foundation pit i , and calculate the average settlement of all points Where, t is the total number of settlement measurement points; S522, calculate the inclination angle I of each point at the bottom of the foundation pit i , and find the average tilt angle of all points Where r is the total number of tilt measurement points; S523. Calculate the horizontal displacement value D of each point at the bottom of the foundation pit h,i , and calculate the average horizontal displacement value of all points Where q is the total number of horizontal displacement measurement points; S53, average settlement Average tilt angle and average horizontal displacement After dimensionless processing, the construction pit deformation index Bxz is calculated by the following related formula: Wherein, J1, J2 and J3 are weight coefficients.

7. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The dynamic design module includes a first association unit and a second association unit; The first correlation unit is used to calculate the cave risk coefficient Fx by the following correlation formula after dimensionless processing of the cave development degree Fcd and the fracture filling condition Cxqk: In the formula, β1 and β2 represent the weight coefficients of cave development degree Fcd and fracture filling condition Cxqk, respectively, and R1 is the first correction constant; The second correlation unit is used to calculate the water inrush risk index Tsq by the following correlation formula after dimensionless processing of the groundwater level fluctuation value Sbz, the soil layer bearing capacity Cz and the construction pit deformation index Bxz: Where β3, β4 and β5 represent the weight coefficients of groundwater level fluctuation value Sbz, construction pit deformation index Bxz and soil bearing capacity Cz respectively, and R2 is the second correction constant.

8. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The cave reinforcement module includes a first evaluation unit and a first strategy unit; The first assessment unit is used to preset a first risk threshold value X1, and compare and analyze the cave risk coefficient Fx with the first risk threshold value X1, and obtain a first assessment result including: When the cave risk coefficient Fx ≥ the first risk threshold X1, it means that the cave risk in the sub-area is abnormal and there is a safety risk in the foundation pit construction. The first filling instruction is generated through the first strategy unit, including reinforcing the area with caves or cracks in the foundation pit area, filling the gaps and caves with self-healing polymers or grouting technology, and setting a support point every 8 meters in the sub-area. The depth of the enclosure structure in the support point is 1.1 times the depth of the foundation pit in the sub-area; When the cave risk coefficient Fx is less than the first risk threshold X1, it means that the cave risk in the sub-area is normal and continuous monitoring is required.

9. The design system for foundation pit retaining structure against sudden water inrush risk according to claim 1 is characterized by: The emergency simulation control module also includes a second evaluation unit and a second strategy unit; The second evaluation unit is used to preset a first water inrush risk threshold value X11 and a second water inrush risk threshold value X12, and the first water inrush risk threshold value X11 is less than the second water inrush risk threshold value X12; The water inrush risk index Tsq is compared and analyzed with the first water inrush risk threshold X11 and the second water inrush risk threshold X12, and the second assessment results are obtained, including: When the water inrush risk index Tsq is less than the first water inrush risk threshold X11, it means: there is no water inrush risk, and normal construction operations and continuous monitoring are continued; When the first water inrush risk threshold X11≤water inrush risk index Tsq≤second water inrush risk threshold X12, it indicates that there is a first water inrush risk, and the second strategy unit generates a first drainage reinforcement instruction, including setting up a drainage system, setting at least two drainage points for every 100 square meters of foundation pit, starting the foundation drainage system, including vertical drainage wells and horizontal drainage pipes, draining water once every hour to reduce 30% of the current water level, and setting a support point every 5 meters in the sub-area, and the depth of the enclosure structure in the support point is 1.2 times the depth of the foundation pit in the sub-area; When the water inrush risk index Tsq is greater than the second water inrush risk threshold X12, it means: there is a second water inrush risk, which is higher than the first risk level and has a high severity. The second strategy unit generates a second drainage reinforcement instruction: including: setting up a drainage system, with at least two drainage points for every 80 square meters of foundation pit, starting the drainage system, including backup drainage equipment and enhanced drainage facilities, draining water every 15-30 minutes to reduce the water level by 50% and carry out emergency reinforcement of the retaining structure, including compacting the soil wall with a vibrating compactor and mixing the soil with a binder to increase the soil wall density by 30%; and setting a support point every 3 meters in the sub-area, and the depth of the retaining structure at the support point is 1.3 times the depth of the sub-area foundation pit; and setting a 15-25% waterproof layer on the outside of the retaining structure.

10. A method for designing a foundation pit retaining structure to prevent sudden water inrush risk, applied to the foundation pit retaining structure design system to prevent sudden water inrush risk according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Conduct geological survey on the area to be constructed, and obtain information on cave distribution and fissure development in the karst strata through multi-scale comprehensive survey technology, generate an initial geological data set, and divide the area to be constructed into several sub-areas; Step 2: During the simulation of foundation pit construction, monitoring points are arranged in several sub-areas, and the groundwater level and deformation parameters of the soil layer at the bottom of the foundation pit are monitored in real time using a sensor network to generate a monitoring data set; Step 3: Screening, filtering, and denoising the initial geological data set and the monitoring data set, and combining dimensionless processing technology to unify data units to establish a geological information database for karst stratum foundation pit construction; Step 4: Based on the geological information database, relevant geological features are extracted to calculate the cave development degree Fcd, soil bearing capacity Cz, crack filling condition Cxqk, groundwater level fluctuation value Sbz and construction pit deformation index Bxz, and the cave risk coefficient Fx is obtained by associating the cave development degree Fcd with the crack filling condition Cxqk; Further correlating the groundwater level fluctuation value Sbz, the soil layer bearing capacity Cz and the construction pit deformation index Bxz to obtain a water inrush risk index Tsq; Step 5: Compare and analyze the cave risk coefficient Fx with the first risk threshold X1. If the cave risk coefficient Fx is higher than or equal to the first risk threshold X1, reinforce the area with caves or cracks in the foundation pit area by using high-strength grouting technology or filling with self-healing materials. Step six: compare and analyze the water inrush risk index Tsq with the first water inrush risk threshold X11 and the second water inrush risk threshold X12 respectively, so as to simulate the automatic triggering of the emergency response mechanism when the water inrush risk occurs and provide corresponding emergency handling strategies.

Images