Dynamic monitoring system for foundation pit confined water precipitation

Abstract

The invention belongs to the technical field of foundation pit confined water precipitation monitoring, and particularly relates to a foundation pit confined water precipitation dynamic monitoring system which comprises a monitoring well laying module, a water pumping test implementation module, a permeation direction distribution determination module, a uniform distribution precipitation monitoring module and a differential distribution precipitation monitoring module. Monitoring wells are arranged in different directions in the surrounding area of the foundation pit before pressure-bearing precipitation operation of the foundation pit, so that a real-time water pumping test is performed, the foundation pit soil permeation direction distribution mode is analyzed by means of a water pumping test result, targeted implementation is provided for subsequent precipitation operation, the settlement risk is reduced on the basis of guaranteeing the precipitation effect to the maximum extent, and the construction period is shortened. In addition, after the permeation direction distribution mode of the foundation pit soil is obtained through analysis, foundation settlement detection is carried out while water level height monitoring is provided in the precipitation operation process in a targeted mode, then the precipitation rate is dynamically adjusted through the comprehensive detection result, potential precipitation risks can be visually recognized, and construction safety is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation pit pressure dewatering monitoring, and in particular relates to a foundation pit pressure dewatering dynamic monitoring system. Background Art

[0002] Foundation pit excavation is a crucial basic construction link in construction projects. It is widely used in projects such as underground parking lots, subway stations and tunnels, aiming to provide construction space for the foundation and underground structure of buildings. During the excavation of the foundation pit, groundwater may flow into the foundation pit, causing the construction environment to be damp or waterlogged, seriously affecting the construction progress and safety. Therefore, it is necessary to carry out pressure dewatering of the foundation pit. Pressure dewatering can effectively lower the groundwater level, reduce the pore water pressure of the soil, enhance the effective stress and shear strength of the soil, ensure the smooth progress of the foundation pit construction and maintain the safety and stability of the surrounding environment.

[0003] It is crucial to monitor the dewatering in real time during the pressure dewatering operation of the foundation pit. There are some operation schemes for monitoring the pressure dewatering of the foundation pit in the prior art. For example, the Chinese invention patent publication number CN113846662A proposes a device and method for graded dewatering of foundation pit excavation. The scheme includes a dewatering well, a pumping device, a water level monitoring device and a control device. The required liquid level value is calculated according to the requirements of graded excavation, and the initial liquid level value and the maximum and minimum liquid level values ​​are set; the pumping device is started when the liquid level value is greater than or equal to the maximum liquid level value; the pumping device is turned off when the liquid level value is less than or equal to the minimum liquid level value. This method can effectively reduce the excessive settlement caused by the sudden drop in the groundwater level around the foundation pit and ensure the safety of buildings around the foundation pit.

[0004] Another patent publication number CN203066091U discloses a foundation pit dewatering and pumping test monitoring system, which can track, monitor and control the foundation pit dewatering and pumping tests in real time, identify possible risks in advance and take corresponding measures to ensure the safety of foundation pit excavation and the real-time accuracy of geotechnical water data information.

[0005] Although the above two technical solutions provide effective monitoring and control means in the foundation pit dewatering operation, no matter it is graded dewatering or pumping test dewatering, there is a lack of preliminary analysis of the soil properties of the foundation pit before the dewatering operation, especially the analysis of the infiltration direction distribution. This is because when groundwater is extracted during the dewatering process, the soil particles may be rearranged, affecting the permeability characteristics of the soil, thereby causing the unevenness of the groundwater level change rate. When there is a lack of analysis of the infiltration direction distribution of the foundation pit soil, it means that the dewatering operation is usually based on a fixed dewatering area. Due to the failure to consider the differences in soil permeability characteristics, some areas may have poor dewatering effects, while other areas may have excessive dewatering. In addition, it may cause the groundwater level in some areas to change too quickly, causing local settlement, which not only affects the dewatering effect, but also increases the risk of settlement invisibly. Summary of the invention

[0006] The purpose of the present invention is to improve the deficiencies in the prior art and to provide a foundation pit pressurized water dewatering dynamic monitoring system, which optimizes the dewatering operation by adding an analysis of the soil seepage direction distribution before the foundation pit pressurized water dewatering operation.

[0007] The purpose of the present invention can be achieved through the following technical solutions: A foundation pit confined water dewatering dynamic monitoring system, comprising the following modules: a monitoring well layout module, used to layout monitoring wells in different directions around the foundation pit.

[0008] The pumping test implementation module is used to implement a pumping test in the deployed monitoring wells, thereby conducting a permeability analysis of each monitoring well.

[0009] The infiltration direction distribution determination module is used to determine the infiltration direction distribution pattern of the foundation pit soil based on the infiltration analysis results of each monitoring well in the pumping test.

[0010] The evenly distributed precipitation monitoring module is used to select representative monitoring wells to carry out precipitation operations when the infiltration direction distribution pattern of the foundation pit soil is determined to be evenly distributed, and to conduct water level and foundation settlement detection during the precipitation operation, and adjust the precipitation speed accordingly.

[0011] The differential distribution precipitation monitoring module is used to divide the precipitation area around the foundation pit into zones when the infiltration direction distribution pattern of the foundation pit soil is determined to be differentially distributed, and to formulate the precipitation sequence of each zone, and then to perform zone follow-up adjustment of the precipitation speed when executing the precipitation operation according to the precipitation sequence.

[0012] In combination with the above technical scheme, the positive effect of the present invention is as follows: the present invention arranges monitoring wells in different directions in the area around the foundation pit before the pressure dewatering operation of the foundation pit, thereby conducting a real-time pumping test, and then uses the pumping test results to analyze the distribution pattern of the soil infiltration direction of the foundation pit, providing targeted implementation for subsequent dewatering operations, which is conducive to achieving balanced dewatering and reducing the risk of settlement while maximizing the dewatering effect.

[0013] Optionally, when the infiltration direction distribution pattern of the foundation pit soil is determined to be uniformly distributed, a representative monitoring well is selected to carry out dewatering operations. In this process, the operation of adjusting the dewatering speed by using the water level height and foundation settlement detection is as follows: the water level height regularly collected during the dewatering operation of the representative monitoring well is compared with the design water level height of the foundation pit construction pressure, and the settlement height of each settlement observation point is compared with the set allowable settlement height. If the settlement height of a settlement observation point at a certain collection time exceeds the allowable settlement height or the water level at a certain collection time reaches the design water level height, the dewatering operation is stopped, otherwise the dewatering operation is continued.

[0014] During the continuous precipitation operation, the water level height collected regularly is compared with the water level height at the last collection time to calculate the water level drop rate.

[0015] The water level drop rate at each collection time is used to identify the mutations of adjacent collection times. If a sudden drop in the water level at a certain collection time is identified, the mutation direction is further determined. If the water level drop rate suddenly slows down, the precipitation rate is increased; if the water level drop rate suddenly speeds up, the precipitation rate is reduced.

[0016] Optionally, when the infiltration direction distribution pattern of the foundation pit soil is determined to be a differential distribution, precipitation zoning and precipitation sequence are formulated, and the precipitation speed zoning follow-up adjustment operation is performed in the precipitation operation according to the precipitation sequence as follows: first select the precipitation area ranked first according to the precipitation sequence of the precipitation areas, and select representative monitoring wells within the precipitation area.

[0017] While dewatering operations are being carried out in representative monitoring wells in the first dewatering area, foundation settlement detection and water level height measurement are carried out simultaneously.

[0018] According to the real-time monitored foundation settlement data and water level height data, the precipitation rate in the first precipitation area is adjusted, and the direction and number of each adjustment are recorded.

[0019] Whether the adjustment of precipitation speed is frequent is judged based on the adjustment frequency. If it is not frequent, the initial precipitation speed of the next precipitation area will maintain the final precipitation speed of the first precipitation area. If it is frequent, the adjustment tendency will be further analyzed. If the adjustment tends to increase the precipitation speed, the initial precipitation speed of the next precipitation area will be higher than the final precipitation speed of the first precipitation area according to the set ratio. If the adjustment tends to reduce the precipitation speed, the initial precipitation speed of the next precipitation area will be lower than the final precipitation speed of the first precipitation area according to the set ratio, until the precipitation speed of the last precipitation area is adjusted.

[0020] The positive effects obtained by adopting the above technical solution are as follows: after analyzing the infiltration direction distribution pattern of the foundation pit soil, targeted precipitation operations are carried out while providing water level monitoring and foundation settlement detection, and then the precipitation speed is dynamically adjusted using the foundation settlement and water level data. This allows for intuitive identification of potential precipitation risks, so that remedial measures can be taken quickly to ensure construction safety. In addition, dynamic adjustment of the precipitation speed based on real-time data can optimize the precipitation process and avoid excessive or insufficient precipitation, thereby improving overall precipitation efficiency and reducing unnecessary shutdowns and rework. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0022] Figure 1 It is a schematic diagram of system module connection of the present invention.

[0023] Figure 2 It is a schematic diagram of the layout of monitoring wells corresponding to the approximately rectangular foundation pit in the present invention.

[0024] Figure 3 This is a diagram of the precipitation speed adjustment operation in the present invention. DETAILED DESCRIPTION

[0025] 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.

[0026] The present invention proposes a foundation pit confined water dewatering dynamic monitoring system, including a monitoring well layout module, a pumping test implementation module, a seepage direction distribution determination module, a uniform distribution dewatering monitoring module, and a differential distribution dewatering monitoring module. Figure 1 As shown, after the monitoring well layout module is implemented, the pumping test implementation module is operated, after the pumping test implementation module is implemented, the infiltration direction distribution determination module is operated, and after the infiltration direction distribution determination module is implemented, the uniform distribution precipitation monitoring module and the differential distribution precipitation monitoring module are operated respectively.

[0027] The monitoring well layout module is used to layout monitoring wells in different directions around the foundation pit.

[0028] It is understandable that the monitoring wells arranged in the area around the foundation pit are first used to implement dewatering operations. By installing a water pump in the monitoring well, the groundwater level can be effectively lowered to achieve the role of the dewatering well. Secondly, they are used for pumping tests to detect the changes in water levels after pumping, so as to obtain the permeability characteristics of the soil and provide basic data for dewatering design.

[0029] It is further understood that the permeability characteristics of soil are usually not uniform, but vary with direction and location. Especially under complex geological conditions, soil structure, particle composition and pore distribution in different directions may vary significantly. By arranging monitoring wells in different directions, the permeability characteristics of the soil around the foundation pit can be fully understood, ensuring that the precipitation operation is more targeted and effective.

[0030] The monitoring well layout process in the above scheme is implemented as follows: collecting foundation pit images and extracting foundation pit boundary contour lines from the foundation pit images.

[0031] Optimally, the acquisition of foundation pit images can use equipment such as drones, laser scanners or high-resolution cameras to obtain high-precision images of foundation pits. In addition, after the image acquisition is completed, the acquired images are preprocessed, including noise removal and correction. The noise removal is aimed at improving the image quality, and the correction is aimed at geometrically correcting the image to eliminate errors caused by factors such as shooting angles and lens distortion, to ensure the authenticity and accuracy of the image.

[0032] In another optimization, the foundation pit boundary contour line can be extracted from the foundation pit image by using edge detection algorithm, contour tracking algorithm, etc.

[0033] Capture the geometric center point on the foundation pit boundary contour line and evenly distribute the points on the boundary contour line.

[0034] It should be noted that the geometric center point mentioned above refers to the centroid of the foundation pit contour line, which can represent the average level of the entire foundation pit area and provide a global reference point. The boundary contour line layout can capture the changes in geological conditions at different locations on the edge of the foundation pit.

[0035] Monitoring wells are deployed at each location on the captured geometric center point and boundary contour line.

[0036] It can be understood that by arranging monitoring wells at the geometric center point and boundary contour points, comprehensive coverage of the foundation pit area can be achieved, ensuring that the soil permeability characteristics in all directions can be effectively monitored.

[0037] It should be added that the specific implementation method of evenly distributing points on the boundary contour line is: evenly select several key positions on the boundary contour line of the foundation pit as monitoring points, and specifically select the following methods: Evenly spaced points: divide the boundary contour line into several equal segments, and set a monitoring well at the midpoint of each segment.

[0038] Distribution of important turning points: Monitoring wells are set up at important turning points of the foundation pit contour line (such as the intersection of two sides).

[0039] Combine the two: On the basis of equally spaced points, additional consideration is given to important turning points to ensure a more reasonable distribution of monitoring points.

[0040] It is further necessary to add that when the monitoring wells are arranged at the above-mentioned corresponding positions, the depth of the monitoring wells should reach a certain distance below the main aquifer (such as 5-10 meters) to ensure that the changes in the groundwater level can be accurately reflected. Specifically, a drilling rig can be used to drill holes at the corresponding arrangement positions, and the hole diameter should be slightly larger than the outer diameter of the monitoring well pipe. After the drilling is completed, the monitoring well pipe with the water filter section is lowered into the hole and backfilled with fine sand or gravel to a certain depth below the ground to prevent surface water from infiltrating. Finally, the top of the monitoring well pipe is sealed to prevent rainwater and other pollutants from entering the well.

[0041] In the above monitoring well deployment implementation example, see Figure 2 As shown, assuming there is an approximately rectangular foundation pit, the four corners and the midpoint of each side can be selected on the boundary of the foundation pit as the layout locations of the monitoring wells.

[0042] The pumping test implementation module is used to implement a pumping test in the deployed monitoring wells, thereby performing a permeability analysis of each monitoring well.

[0043] In the above-mentioned achievable manner, the pumping test is carried out in the deployed monitoring wells according to the following process: an observation well is selected near each deployed monitoring well, and a water level sensor is arranged in the observation well.

[0044] It should be noted that when configuring the water level sensor, ensure that the sensor is located a certain distance above the bottom of the well (such as 0.5 meters) to avoid mud and sand clogging the sensor.

[0045] Lower the pump to an appropriate depth in the monitoring well (usually in the middle or slightly lower part of the aquifer), connect the outlet pipe, and install a flow meter on the outlet pipe.

[0046] Before starting to pump water, the water level sensor is used to collect and record the initial groundwater level in the observation well.

[0047] The pumping test is started at a predetermined pumping rate (e.g. 5 m³ / h), and the pumping volume of the monitoring well and the groundwater level of the observation well are recorded after a preset interval (e.g. 30 minutes). The pumping volume can be obtained by a flow meter.

[0048] The water level drop at each time point is obtained using the groundwater level in the observation well and the initial groundwater level, where the water level drop is equal to the initial groundwater level minus the current water level.

[0049] It should be noted that the observation wells mentioned above are used to monitor the change of groundwater level, and are usually used in conjunction with monitoring wells for pumping operations. In the pumping test, the monitoring wells are used for pumping operations, while the observation wells are used to record the change of water level. The permeability characteristics of the aquifer in the monitoring well can be calculated through the data of the observation wells. Of course, more than one observation well can be selected. The observation wells close to the monitoring wells will record a greater water level drop, because these locations are more affected by the pumping wells. The observation wells far away from the monitoring wells record a smaller water level drop. Multiple observation wells can be set at different distances from the monitoring wells to achieve reliable analysis of the permeability characteristics of the aquifer.

[0050] After reaching a predetermined pumping time (eg, 24 hours), the pump is stopped, and the water level drawdown and pumping volume data at different time points are used to analyze the permeability coefficient of each monitoring well.

[0051] In the specific implementation of the above scheme, the permeability coefficient of each monitoring well is analyzed as follows: Since it is a foundation pit pressurized dewatering, the Theis method or the Jacob method can be used, among which the Theis method is applicable to the unstable conditions of the confined aquifer, and the Jacob method is applicable to the approximate steady-state conditions of the confined aquifer. It is a simplified method that assumes that the groundwater flow is close to the steady-state conditions. It is usually used to analyze data after long-term pumping and can be selected according to needs.

[0052] Specifically, the core formula of Theis method is: ,in Indicates that the water level has dropped. Indicates the amount of water pumped. represents the hydraulic conductivity, , represents the permeability coefficient, represents the thickness of the aquifer, is the Theis well function, and its expression is , is the water storage coefficient, is the distance from the observation well to the pumping well, It's time. is the ratio of pi.

[0053] It should be pointed out that when conducting the pumping test of each monitoring well, each monitoring well is used as a pumping well for the pumping test.

[0054] The implementation steps of the Theis method are as follows: conduct a pumping test in a pumping well and record the initial water level, pumping rate, pumping time and water level change data of the observation well.

[0055] Based on the data from the observation well, a curve showing the change of water level drop over time is drawn.

[0056] Using Theis well function and Determine the hydraulic conductivity by fitting the curve and Water storage coefficient.

[0057] Using hydraulic conductivity Combined water storage coefficient Calculate the permeability coefficient .

[0058] The core formula of Jacob's method is: ,in Indicates that the water level has dropped. Indicates the amount of water pumped. represents the hydraulic conductivity, , represents the permeability coefficient, represents the thickness of the aquifer, is the distance from the observation well to the pumping well, It's time. is the water storage coefficient.

[0059] The implementation steps of the Jacob method are as follows: Same as the Theis method, record the initial water level, pumping rate, pumping time and water level change data of each observation well.

[0060] Based on the data from the observation well, a curve showing the change of water level drop over time is drawn.

[0061] use Formula to determine the hydraulic conductivity by fitting the curve and Water storage coefficient.

[0062] Using hydraulic conductivity Combined water storage coefficient Calculate the permeability coefficient .

[0063] It should be noted that the above-mentioned permeability coefficient analysis based on the water level drawdown and pumping volume data in the pumping test using the Theis method or the Jacob method has been widely used and described in detail in the prior art. The specific operation details will not be repeated in this document.

[0064] It should be understood that the permeability coefficient of the monitoring well refers to the hydraulic conductivity of the soil or rock formation where the monitoring well is located. Specifically, it describes the ability of groundwater to pass through the pores or cracks of the soil or rock. Permeability coefficient is a key hydrogeological parameter used to evaluate the speed and direction of groundwater flow. It is defined according to Darcy's law and represents the flow rate of groundwater under unit hydraulic gradient. Factors affecting soil permeability coefficient include soil particle size and arrangement, pore structure, saturation, etc. Among them, permeability coefficient is closely related to the size, shape and arrangement of soil particles. Generally speaking, soils with larger particles and loose arrangement (such as sand and gravel) have higher permeability coefficients; while soils with smaller particles and dense arrangement (such as clay) have lower permeability coefficients. Among them, the pore or crack structure in the soil or rock also affects the permeability coefficient. Larger pores or cracks allow water to pass more easily, thereby increasing the permeability coefficient. Among them, the permeability coefficient is also affected by the water content of the soil under unsaturated conditions. Generally, the permeability coefficient of saturated soil is higher, while the permeability coefficient of unsaturated soil is lower.

[0065] The permeability direction distribution analysis module is used to analyze the permeability direction distribution pattern of the foundation pit soil based on the permeability coefficient of each monitoring well in the pumping test. The specific analysis is as follows: the monitoring wells corresponding to the geometric center points in the foundation pit boundary contour are respectively connected with the monitoring wells corresponding to the boundary contour points to form a number of directional lines.

[0066] The absolute permeability difference of each direction is obtained by taking the difference between the permeability coefficient of the monitoring well corresponding to the geometric center point of each direction line and the permeability coefficient of the monitoring well corresponding to the boundary contour point and taking the absolute value.

[0067] The distance of each pointing line is obtained respectively as the pointing distance.

[0068] The absolute penetration difference of each directional line is used as the characteristic vector to form a The data matrix of the pointing line is specifically the absolute penetration difference and the pointing distance.

[0069] The permeability coefficient of the monitoring well corresponding to the geometric center point and the permeability coefficient of the monitoring well corresponding to the boundary contour point are recorded as , , Indicates the pointing line number. , each pointing line The absolute permeability difference , pointing distance , the constructed feature vector , the constructed data matrix is .

[0070] The data matrix is ​​standardized so that each column has zero mean and unit variance.

[0071] The purpose of the above standardization is to eliminate the feature differences between different dimensions and ensure that the features are compared on the same scale. Specifically, the standardization can be achieved by subtracting the mean of the column in which each element in the data matrix is ​​located and then dividing it by the standard deviation of the column. This processing method makes each column of data have zero mean and unit variance.

[0072] Calculate the covariance matrix of the standardized data matrix and obtain the eigenvalues ​​and eigenvectors of the covariance matrix.

[0073] The above-mentioned standardized data matrix is ​​recorded as , the covariance matrix is ​​recorded as , , the eigenvalues ​​of the covariance matrix and the eigenvector ,in .

[0074] The first few principal components are selected according to the size of the eigenvalues. Usually, the principal components whose cumulative contribution rate reaches a certain threshold (such as 80% or 90%) are selected. The standardized data are then projected onto the principal components to obtain the score of each pointing line sample on the principal component, and the contribution rate of each principal component is calculated.

[0075] It is important to understand that the principal component contribution rate (that is, the proportion of data variance explained by each principal component) tells us the proportion of each principal component in the overall data variation. The specific calculation method is to divide the eigenvalue corresponding to the principal component by the sum of all eigenvalues. This helps to understand which principal components are the most important and which are secondary.

[0076] In the above example, suppose there are three principal components, their eigenvalues ​​are 5.0, 2.0, and 1.0, respectively, and the sum of the eigenvalues ​​is 5.0+2.0+1.0=8.0. The contribution rate of each principal component is , , .

[0077] High contributing principal components: These principal components explain most of the variation in the data and usually reflect major trends or patterns.

[0078] Low contributing principal components: These principal components explain less variation in the data and may contain noise or minor trends.

[0079] By calculating the principal component contribution rate, we can decide how many principal components need to be retained. Usually, the criterion for selecting principal components is based on the cumulative contribution rate, that is, the sum of the contribution rates of the first few principal components. A common practice is to select principal components whose cumulative contribution rate reaches a certain threshold (such as 80% or 90%) to simplify the model and reduce redundant information.

[0080] The trend principal component is selected according to the principal component contribution rate, and the standard deviation of the score of each trend principal component is calculated. If the standard deviation of all trend principal component scores is less than the set threshold, the infiltration direction distribution mode is determined to be uniform distribution, otherwise, the infiltration direction distribution mode is determined to be differential distribution.

[0081] In the above example, the threshold value of the standard deviation is set to 0.1.

[0082] It should be explained that the principal components with the greatest impact on data variation can be identified through the principal component contribution rate. These principal components reflect the main trends of foundation pit soil infiltration. For example, there are three principal components selected, the contribution rate of the first principal component is 70%, the contribution rate of the second principal component is 25%, and the contribution rate of the third principal component is 5%. In this case, the first two principal components have explained 95% of the data variance. Therefore, it can be considered that the first two principal components are sufficient to reflect the main trends of foundation pit soil infiltration and are regarded as trend principal components.

[0083] It is further explained that the standard deviation of the trend principal component score is used to evaluate the degree of dispersion of each trend principal component score, helping us to judge the uniformity or difference of the data in the direction of each trend principal component. When the standard deviation is low, it means that the data points in the direction of the trend principal component are more concentrated, indicating that the change in the permeability coefficient in this direction is small. When the standard deviation is high, it means that the data points in the direction of the trend principal component are more dispersed, indicating that the change in the soil permeability coefficient in the direction of the trend principal component is large.

[0084] It is worth noting that the above analysis of the infiltration direction distribution pattern of foundation pit soil based on the infiltration difference and pointing distance of soil at different pointing line positions is carried out by principal component analysis. The infiltration difference of soil at different pointing line positions reflects the difference in infiltration capacity between different positions, and the pointing distance provides geometric information to help understand the spatial relationship between different monitoring points. Combining the two can provide richer information and more comprehensively describe the infiltration characteristics of foundation pit soil. In actual engineering, the infiltration characteristics of foundation pit soil are often affected by many factors, such as depth, geological structure, groundwater level, etc. Through dimensionality reduction techniques such as principal component analysis, the main trends and patterns can be extracted from complex high-dimensional data, thereby simplifying the problem and highlighting key information. In addition, the principal component scores obtained by principal component analysis can be visualized in two-dimensional or three-dimensional space to intuitively display the distribution of foundation pit soil infiltration characteristics. This not only helps engineers and technicians better understand the data, but can also be used for reporting and communication.

[0085] The infiltration direction distribution pattern obtained through principal component analysis can provide a scientific basis for the design and optimization of foundation pit dewatering schemes. Specifically, if the infiltration direction distribution pattern is uniform and the groundwater flow is relatively stable, a simpler dewatering scheme can be selected to reduce unnecessary complexity and cost. If there is a significant difference in distribution, it means that in some local areas, the permeability of the soil is significantly different from that in other areas, and the groundwater flow is also uneven. In this case, targeted measures need to be taken, such as local intensification of precipitation or the adoption of different precipitation strategies to ensure the precipitation effect.

[0086] The uniformly distributed precipitation monitoring module is used to select representative monitoring wells to carry out precipitation operations when the infiltration direction distribution pattern of the foundation pit soil is determined to be uniformly distributed, and to perform water level height and foundation settlement detection during the precipitation operation, thereby adjusting the precipitation speed.

[0087] Preferably, the representative monitoring well is selected as follows: a monitoring well corresponding to a geometric center point within the boundary contour of the foundation pit is selected as the representative monitoring well.

[0088] In the above-mentioned case of uniform distribution, the soil permeability characteristics in the foundation pit area are relatively consistent, and the groundwater flow is relatively stable. Therefore, only one representative monitoring well needs to be selected to reflect the situation of the entire foundation pit area, and there is no need to arrange monitoring wells in multiple locations. Reducing the number of monitoring wells can reduce the difficulty and cost of construction, and simplify subsequent maintenance. Selecting a monitoring well in the center can better cover the entire foundation pit area and ensure the balance of the precipitation effect.

[0089] Further preferably, the foundation settlement detection refers to the following process: a settlement observation point is set at each boundary contour point of the foundation pit boundary contour, and a settlement monitoring device is installed at each settlement observation point.

[0090] It can be understood that setting settlement observation points at the boundary contour points of the foundation pit can ensure comprehensive coverage of the entire area around the foundation pit and capture the settlement conditions at various locations along the edge of the foundation pit.

[0091] The settlement monitoring equipment selected in the above scheme may be a level, a total station, etc.

[0092] A fixed reference point (such as a steel pile or concrete marker) is set at each settlement observation point, and the height difference of each settlement observation point relative to the reference point is measured in real time during the precipitation operation as the settlement height.

[0093] The above-mentioned settlement detection sets a fixed reference point to provide a stable reference point for settlement observation, ensuring that the reference point is consistent during each measurement and avoiding data errors caused by changes in the reference point.

[0094] Still preferably, the dewatering speed adjustment is implemented as follows: the water level height collected regularly during the dewatering operation of the representative monitoring well is compared with the design water level height for foundation pit construction pressure, and the settlement height of each settlement observation point is compared with the set allowable settlement height. If the settlement height of a settlement observation point at a certain collection time exceeds the allowable settlement height or the water level at a certain collection time reaches the design water level height, the dewatering operation is stopped, otherwise the dewatering operation is continued.

[0095] The above-mentioned design water level for the construction of the foundation pit is determined based on detailed engineering design documents and geological survey reports before the foundation pit dewatering operation. The main purpose of the design water level is to prevent sudden surges at the bottom of the foundation pit and to avoid instability or collapse of the foundation pit due to excessive groundwater pressure. The allowable settlement height can be obtained through geological surveys. The allowable settlement height is used to evaluate the impact of foundation pit excavation and dewatering operations on the surrounding strata, ensuring that buildings, underground pipelines and other facilities around the foundation pit will not be damaged due to excessive settlement during the construction process.

[0096] During the continuous precipitation operation, the water level height collected regularly is compared with the water level height at the last collection time to calculate the water level drop rate.

[0097] The water level drop rate at each collection time is used to identify the mutation of the adjacent collection time. Specifically, the mutation identification can be performed by subtracting the water level drop rates at adjacent collection times to obtain the water level drop rate difference, and compare it with the preset allowable water level drop rate difference. If the water level drop rate difference at a certain adjacent collection time is higher than the allowable water level drop rate difference, it is identified that there is a mutation in the water level drop rate. If a sudden drop in the water level at a certain collection time is identified, the mutation direction is further determined. If the water level drop speed is suddenly slow, the precipitation speed is increased, and the specific operation includes increasing the number of water pumps or increasing the operating frequency of the pumps. If the water level drop speed is suddenly fast, the precipitation speed is reduced, and the specific operation includes reducing the number of water pumps or reducing the operating frequency of the pumps.

[0098] Through the above method, the water level and settlement height can be effectively monitored during the precipitation operation, and the precipitation speed can be adjusted in time to ensure construction safety and efficiency. This method can not only provide reliable monitoring data, but also help optimize the precipitation effect and avoid unnecessary risks and costs.

[0099] See also Figure 3 As shown, the differential distribution precipitation monitoring module is used to divide the precipitation area around the foundation pit into zones when the infiltration direction distribution pattern of the foundation pit soil is determined to be differentially distributed, and formulate a precipitation sequence for each zone, and then perform zone follow-up adjustment of the precipitation speed when executing the precipitation operation according to the precipitation sequence.

[0100] In the improved implementation of the above scheme, the precipitation zoning of the area around the foundation pit is specifically implemented as follows: the permeability coefficients of adjacent monitoring wells are identified to be similar for each monitoring well except the monitoring well corresponding to the geometric center point of the foundation pit boundary contour. Specifically, the similar identification can be performed by taking the absolute value of the difference between the permeability coefficients of adjacent monitoring wells and comparing it with the preset similar permeability difference threshold. If the absolute value difference of the permeability coefficients of adjacent monitoring wells is less than or equal to the similar permeability difference threshold, the permeability coefficients of the adjacent monitoring wells are identified to be similar. If the permeability coefficients of a pair of adjacent monitoring wells are similar, the two monitoring wells and the area where they are located are regarded as a precipitation area. If the permeability coefficients of a pair of adjacent monitoring wells are not similar, the area where the two monitoring wells are located is divided into two independent precipitation areas.

[0101] The above-mentioned division of precipitation areas based on the permeability coefficient in the direction of adjacent monitoring wells can achieve more refined and efficient precipitation management. Since there are significant differences in soil permeability characteristics in different areas, the pumping rate and strategy can be adjusted according to the specific permeability coefficient of each area through zoned precipitation to ensure a more uniform precipitation effect. In addition, by independently controlling different areas, the groundwater level can be prevented from dropping sharply due to excessive pumping, thereby ensuring the safety of the foundation pit and surrounding environment.

[0102] In further improvement implementation, the precipitation order of each zone is formulated as follows: the permeability coefficient of each precipitation area is obtained, and the precipitation area is arranged in order of permeability coefficient from large to small to obtain the precipitation order of the precipitation area.

[0103] In the above description, since there are multiple monitoring wells in a precipitation area, when obtaining the permeability coefficient corresponding to the precipitation area to which multiple monitoring wells with similar permeability coefficients belong, the permeability coefficients of different monitoring wells in the precipitation area can be averaged to obtain the permeability coefficient of the precipitation area.

[0104] It should be understood that, generally, groundwater levels in areas with high permeability coefficients change more rapidly, so precipitation operations should be given priority to avoid problems such as soil instability caused by a rapid drop in local water levels during precipitation.

[0105] In further improvement and implementation, the zoning and adjustment of precipitation speed refer to the following process: first select the precipitation area ranked first according to the precipitation order of the precipitation areas, and select representative monitoring wells (such as the monitoring well corresponding to the geometric center point) in the precipitation area.

[0106] While dewatering operations are being carried out in representative monitoring wells in the first dewatering area, foundation settlement detection and water level height measurement are carried out simultaneously.

[0107] According to the real-time monitored foundation settlement data and water level height data, the precipitation rate in the first precipitation area is adjusted. The specific adjustment strategy can refer to the precipitation rate adjustment of the representative monitoring well under uniform distribution, and the direction (increase or decrease) and number of adjustments of each adjustment are recorded.

[0108] Whether the adjustment of precipitation speed is frequent is judged based on the number of adjustments. If it is not frequent, the initial precipitation speed of the next precipitation area will maintain the final precipitation speed of the first precipitation area. If it is frequent, the adjustment tendency will be further analyzed. Specifically, the proportion of increased and decreased adjustment times can be statistically analyzed to extract the adjustment direction with a larger proportion. If the adjustment tends to increase the precipitation speed, the initial precipitation speed of the next precipitation area will be higher than the final precipitation speed of the first precipitation area according to a set ratio (such as 5%-10%). If the adjustment tends to reduce the precipitation speed, the initial precipitation speed of the next precipitation area will be lower than the final precipitation speed of the first precipitation area according to a set ratio, until the precipitation speed of the last precipitation area is adjusted.

[0109] In the above implementation example, assuming that in an approximately rectangular foundation pit project, the foundation pit has been divided into three precipitation areas (A, B, C), and the precipitation order is set as A->B->C. Assume that three adjustments were made during the operation of precipitation area A, two of which increased the precipitation speed and one reduced the precipitation speed. Due to the large number of adjustments, it is judged that the adjustments are too frequent. Further analysis shows that the adjustment direction mainly tends to increase the precipitation speed. The initial precipitation speed of the next precipitation area B should be increased by a certain proportion (such as 5%-10%) based on the final precipitation speed of area A.

[0110] The above method can be used to effectively monitor the water level and settlement height during precipitation operations, and adjust the precipitation speed in subsequent precipitation areas in a timely manner accordingly to ensure construction safety and efficiency.

[0111] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A foundation pit confined water dewatering dynamic monitoring system, characterized in that: Includes the following modules: Monitoring well layout module, used to layout monitoring wells in different directions around the foundation pit; A pumping test implementation module is used to implement a pumping test in the deployed monitoring wells, thereby conducting a permeability analysis of each monitoring well; A seepage direction distribution determination module is used to determine the seepage direction distribution pattern of foundation pit soil based on the seepage analysis results of each monitoring well in the pumping test; The evenly distributed precipitation monitoring module is used to select representative monitoring wells to carry out precipitation operations when the infiltration direction distribution pattern of the foundation pit soil is determined to be evenly distributed, and to detect the water level and foundation settlement during the precipitation operation, and adjust the precipitation speed accordingly; The differential distribution precipitation monitoring module is used to divide the precipitation area around the foundation pit into zones when the infiltration direction distribution pattern of the foundation pit soil is determined to be differentially distributed, and to formulate the precipitation sequence of each zone, and then to perform zone follow-up adjustment of the precipitation speed when executing the precipitation operation according to the precipitation sequence.

2. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 1, characterized in that: The deployment of monitoring wells in different directions around the foundation pit is implemented as follows: Collect foundation pit images, and extract foundation pit boundary contour lines from the foundation pit images; Capture the geometric center point on the boundary contour line of the foundation pit and evenly distribute the points on the boundary contour line; Monitoring wells are deployed at each location on the captured geometric center point and boundary contour line.

3. A foundation pit pressurized water dewatering dynamic monitoring system as claimed in claim 2, characterized in that: The permeability analysis of each monitoring well is performed as follows: Select an observation well near each deployed monitoring well and configure a water level sensor in the observation well; Lower the water pump to an appropriate depth in the monitoring well, connect the outlet pipe, and install a flow meter on the outlet pipe; Measure and record the initial groundwater level in the observation well before pumping begins; Start the pumping test at a predetermined pumping rate and record the pumping volume of each monitoring well and the groundwater level of the corresponding observation well after a preset interval; The water level drop at each time point is obtained by using the groundwater level and initial groundwater level of the observation well at each time point; The pump is stopped after the preset pumping time is reached, and the water level drop and pumping volume data at different time points are used to analyze the permeability coefficient of each monitoring well.

4. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 3, characterized in that: The process of determining the distribution pattern of foundation pit soil infiltration direction is as follows: The monitoring wells corresponding to the geometric center points in the foundation pit boundary contour are respectively connected with the monitoring wells corresponding to the boundary contour points to form a plurality of pointing lines; The absolute permeability difference of each direction is obtained by taking the difference between the permeability coefficient of the monitoring well corresponding to the geometric center point of each direction line and the permeability coefficient of the monitoring well corresponding to the boundary contour point and taking the absolute value; respectively obtaining the distance of each pointing line as the pointing distance; The absolute penetration difference of each directional line is used as the characteristic vector to form a The data matrix of , where the pointing line characteristics are the absolute penetration difference and the pointing distance; The data matrix is ​​standardized so that each column of data has zero mean and unit variance; Calculate the covariance matrix of the standardized data matrix and obtain the eigenvalues ​​and eigenvectors of the covariance matrix; Select the first few principal components according to the size of the eigenvalue, and then project the standardized data onto the principal components to obtain the score of each pointing line sample on the principal component, and calculate the contribution rate of each principal component; The trend principal component is selected according to the principal component contribution rate, and the standard deviation of the score of each trend principal component is calculated. If the standard deviation of all trend principal component scores is less than the set threshold, the infiltration direction distribution mode is determined to be uniform distribution, otherwise, the infiltration direction distribution mode is determined to be differential distribution.

5. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 2, characterized in that: The selection of representative monitoring wells is performed as follows: The monitoring well corresponding to the geometric center point within the foundation pit boundary contour is selected as the representative monitoring well.

6. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 2, characterized in that: The foundation settlement detection refers to the following process: Set up settlement observation points at each boundary contour point of the foundation pit boundary contour, and install settlement monitoring equipment at each settlement observation point; A fixed reference point is set at each settlement observation point, and the height difference of each settlement observation point relative to the reference point is measured in real time during the precipitation operation as the settlement height.

7. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 6, characterized in that: The precipitation speed adjustment is implemented as follows: The water level collected regularly during the dewatering operation of the representative monitoring well is compared with the design water level of the foundation pit construction pressure, and the settlement height of each settlement observation point is compared with the set allowable settlement height. If the settlement height of a settlement observation point at a certain collection time exceeds the allowable settlement height or the water level at a certain collection time reaches the design water level, the dewatering operation is stopped, otherwise the dewatering operation is continued; During the continuous precipitation operation, the water level height collected regularly is compared with the water level height at the last collection time to calculate the rate of water level drop; The water level drop rate at each collection time is used to identify the mutations of adjacent collection times. If a sudden drop in the water level at a certain collection time is identified, the mutation direction is further determined. If the water level drop rate suddenly slows down, the precipitation rate is increased; if the water level drop rate suddenly speeds up, the precipitation rate is reduced.

8. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 3, characterized in that: The specific implementation of the precipitation zoning for the area around the foundation pit is as follows: The permeability coefficients of adjacent monitoring wells are identified to be similar for all monitoring wells except the monitoring well corresponding to the geometric center point of the foundation pit boundary contour. If the permeability coefficients of a pair of adjacent monitoring wells are similar, the two monitoring wells and the area where they are located are regarded as one precipitation area. If the permeability coefficients of a pair of adjacent monitoring wells are not similar, the area where the two monitoring wells are located is divided into two independent precipitation areas.

9. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 8, characterized in that: The precipitation order of each sub-area is formulated as follows: The permeability coefficient of each precipitation area is obtained, and the precipitation area is arranged in descending order according to the permeability coefficient to obtain the precipitation order of the precipitation area.

10. A foundation pit confined water dewatering dynamic monitoring system according to claim 7, characterized in that: The partition follow-up adjustment of the precipitation speed is as follows: According to the precipitation order of the precipitation areas, the first precipitation area is selected first, and a representative monitoring well is selected in the precipitation area; Simultaneously carry out foundation settlement detection and water level height measurement while carrying out dewatering operations in representative monitoring wells in the first dewatering area; According to the real-time monitored foundation settlement data and water level height data, adjust the precipitation rate of the first precipitation area, and record the direction and number of adjustments each time; Whether the adjustment of precipitation speed is frequent is judged based on the number of adjustments. If it is not frequent, the initial precipitation speed of the next precipitation area will maintain the final precipitation speed of the first precipitation area. If it is frequent, the adjustment tendency will be further analyzed. If the adjustment tends to increase the precipitation speed, the initial precipitation speed of the next precipitation area will be higher than the final precipitation speed of the first precipitation area according to the set ratio. If the adjustment tends to reduce the precipitation speed, the initial precipitation speed of the next precipitation area will be lower than the final precipitation speed of the first precipitation area according to the set ratio, until the precipitation speed of the last precipitation area is adjusted.

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