A dynamic monitoring system for confined water dewatering in foundation pits

Abstract

The present invention belongs to the technical field of foundation pit confined water dewatering monitoring, and particularly relates to a dynamic monitoring system for foundation pit confined water dewatering, including a monitoring well layout module, a pumping test implementation module, a seepage direction distribution determination module, a uniformly distributed dewatering monitoring module, and a differentially distributed dewatering monitoring module. By arranging monitoring wells in different directions in the surrounding area of the foundation pit before the foundation pit confined water dewatering operation, real-time pumping tests are carried out, and then the seepage direction distribution pattern of the foundation pit soil is analyzed based on the results of the pumping tests, providing targeted implementation for subsequent dewatering operations, reducing the settlement risk while maximizing the dewatering effect. In addition, during the dewatering operation carried out targeted after analyzing the seepage direction distribution pattern of the foundation pit soil, the water level height is monitored and the foundation settlement is detected at the same time, and then the dewatering rate is dynamically adjusted using the comprehensive detection results, which can intuitively identify potential dewatering risks and ensure construction safety.

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 object of the present invention is to improve the deficiencies existing in the prior art and provide a dynamic monitoring system for dewatering confined water in a foundation pit. By adding an analysis of the soil seepage direction distribution before the dewatering operation of the foundation pit confined water, the optimization of the dewatering operation is realized.

[0007] The object of the present invention can be achieved by the following technical solutions: A dynamic monitoring system for dewatering confined water in a foundation pit, including the following modules: A monitoring well layout module, used to layout monitoring wells in different directions in the surrounding area of the foundation pit.

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

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

[0010] A uniform distribution dewatering monitoring module, used to select representative monitoring wells to carry out dewatering operations when the soil seepage direction distribution pattern of the foundation pit is determined to be a uniform distribution, and to detect the water level height and foundation settlement during the dewatering operation, and accordingly adjust the dewatering speed.

[0011] A differential distribution dewatering monitoring module, used to divide the dewatering area of the surrounding area of the foundation pit when the soil seepage direction distribution pattern of the foundation pit is determined to be a differential distribution, and to formulate the dewatering sequence of each area, and then to perform a zoning follow-up adjustment of the dewatering speed during the dewatering operation in accordance with the dewatering sequence.

[0012] Combined with the above technical solutions, the positive effects of the present invention are as follows: By laying out monitoring wells in different directions in the surrounding area of the foundation pit before the dewatering operation of the foundation pit confined water, a real-time pumping test is carried out, and then the soil seepage direction distribution pattern of the foundation pit is analyzed by means of the pumping test results, providing a targeted implementation for the subsequent dewatering operation, which is conducive to realizing balanced dewatering and reducing the settlement risk on the basis of maximizing the dewatering effect.

[0013] Optionally, when the soil seepage direction distribution pattern of the foundation pit is determined to be a uniform distribution, representative monitoring wells are selected to carry out dewatering operations. The operation of adjusting the dewatering speed by using the water level height and foundation settlement detection is as follows: Compare the water level height regularly collected during the dewatering operation of the representative monitoring wells with the confined water design water level height of the foundation pit construction, and at the same time compare the settlement height of each settlement observation point with the set allowable settlement height. If the settlement height of a certain settlement observation point exceeds the allowable settlement height at a certain collection time or the water level height at a certain collection time reaches the design water level height, stop the dewatering operation, otherwise continue the dewatering operation.

[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 will be further described with reference to the accompanying drawings. However, the embodiments shown in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on the following drawings without creative efforts.

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

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

[0024] Figure 3 It is an operation diagram for adjusting the precipitation rate in the present invention. Specific Embodiments

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0026] The present invention provides a dynamic monitoring system for the dewatering of confined water in a foundation pit, including a monitoring well layout module, a pumping test implementation module, an infiltration direction distribution determination module, a uniformly distributed precipitation monitoring module, and a differentially distributed precipitation monitoring module. Refer to Figure 1 As shown, after the implementation of the monitoring well layout module, the operation of the pumping test implementation module is carried out. After the implementation of the pumping test implementation module, the operation of the infiltration direction distribution determination module is carried out. After the implementation of the infiltration direction distribution determination module, the operations of the uniformly distributed precipitation monitoring module and the differentially distributed precipitation monitoring module are respectively carried out.

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

[0028] It can be understood that laying out monitoring wells in the area around the foundation pit is first used for implementing the dewatering operation. By setting a water pump in the monitoring well, the groundwater level can be effectively reduced to achieve the function of the dewatering well. Secondly, it is used for the pumping test to detect the water level change after pumping to obtain the infiltration characteristics of the soil, providing basic data for the dewatering design.

[0029] Furthermore, it can be understood that the infiltration characteristics of the soil are usually not uniform, but vary with direction and position. Especially under complex geological conditions, there may be significant differences in the soil structure, particle composition, and pore distribution in different directions. By laying out monitoring wells in different directions, the infiltration characteristics of the soil around the foundation pit can be comprehensively understood, ensuring that the dewatering operation is more targeted and effective.

[0030] In the above solution, the implementation of the monitoring well layout process is as follows: Collect the foundation pit images and extract the boundary contour line of the foundation pit from the foundation pit images.

[0031] Preferably, the collection of the foundation pit images can use devices such as drones, laser scanners or high-resolution cameras to obtain high-precision images of the foundation pit. In addition, after the image collection is completed, the collected images are preprocessed, specifically including noise removal and correction. The purpose of noise removal is to improve the image quality, and the purpose of correction is to perform geometric correction on the images to eliminate errors caused by factors such as shooting angles and lens distortions, and ensure the authenticity and accuracy of the images.

[0032] Another preferably, the extraction of the boundary contour line of the foundation pit from the foundation pit images can be performed using edge detection algorithms, contour tracking algorithms, etc.

[0033] Capture the geometric center point on the boundary contour line of the foundation pit and evenly distribute 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 distribution of points on the boundary contour line can capture the changes in geological conditions at different positions on the edge of the foundation pit.

[0035] Install monitoring wells at the captured geometric center point and each point position on the boundary contour line.

[0036] It can be understood that by installing monitoring wells at the geometric center point and the boundary contour points, the 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 as follows: Evenly select several key positions on the boundary contour line of the foundation pit as monitoring points, and specifically select the following several methods: Equal-spacing point distribution: Divide the boundary contour line into several equal segments and set monitoring wells at the midpoint of each segment.

[0038] Point distribution at important turning points: Set monitoring wells at the important turning points (such as the intersection of two sides) of the foundation pit contour line.

[0039] Combining the two: On the basis of equal-spacing point distribution, additionally consider important turning points to ensure a more reasonable distribution of monitoring points.

[0040] It should be further supplemented that when arranging monitoring wells at the corresponding positions mentioned above, the depth of the monitoring wells should reach a certain distance (such as 5 - 10 meters) below the main aquifer 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 a filter pipe section is lowered into the hole, and it is backfilled with fine sand or gravel to a certain depth below the ground surface to prevent surface water from seeping in. Finally, the top of the monitoring well pipe is sealed to prevent rainwater and other pollutants from entering the well.

[0041] In the above-mentioned implementation example of the arrangement of the monitoring wells, refer to Figure 2 As shown, assuming there is an approximately rectangular foundation pit, the four corners and the midpoints of each side can be selected as the arrangement positions of the monitoring wells on the boundary of the foundation pit.

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

[0043] In the above-mentioned achievable manner, the process of conducting a pumping test in the arranged monitoring wells is as follows: Observation wells are selected near each arranged monitoring well, and water level sensors are configured in the observation wells.

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

[0045] The water pump is lowered to an appropriate depth in the monitoring well (usually in the middle or slightly lower position of the aquifer), and the outlet pipe is connected. A flow meter is installed on the outlet pipe.

[0046] Before starting the pumping, the initial groundwater level of the observation well is collected and recorded using the water level sensor.

[0047] The water pump is started to conduct the pumping test at a predetermined pumping rate (such as 5 m³ / h), and the water extraction volume of the monitoring well and the groundwater level of the observation well are recorded after a preset interval time (such as 30 minutes). The water extraction volume can be obtained through the flow meter.

[0048] The water level drawdown at each time point is obtained by using the groundwater level of the observation well at each time point and the initial groundwater level. The water level drawdown is equal to the initial groundwater level minus the current water level.

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

[0050] After reaching the predetermined pumping time (e.g., 24 hours), stop the pump, and thus analyze the permeability coefficient of each monitoring well by using the water level drawdown and pumping volume data at different time points.

[0051] In the specific implementation of the above scheme, the analysis of the permeability coefficient of each monitoring well is as follows: Since it is the confined dewatering of the foundation pit, the Theis method or the Jacob method can be used. Among them, the Theis method is applicable to the unsteady 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 and is usually used to analyze the data after long-term pumping. It can be selected according to the needs.

[0052] Specifically, the core formula of the Theis method is , where represents the water level drawdown, represents the pumping volume, represents the transmissivity, , represents the permeability coefficient, represents the aquifer thickness, is the Theis well function, and its expression is , is the storage coefficient, is the distance from the observation well to the pumping well, is the time, is the pi.

[0053] It should be pointed out that when conducting the pumping test for 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 the pumping well, and record the initial water level, pumping rate, pumping time, and the water level change data of the observation well.

[0055] According to the data of the observation well, draw a curve of the water level drawdown changing with time.

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

[0057] Use the hydraulic conductivity combined with the storage coefficient to calculate the permeability coefficient .

[0058] The core formula of the Jacob method is , where represents the drawdown, represents the pumping rate, represents the hydraulic conductivity, , represents the permeability coefficient, represents the aquifer thickness, is the distance from the observation well to the pumping well, is the time, is the storage coefficient.

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

[0060] According to the data of the observation well, plot the curve of the drawdown varying with time.

[0061] Use the formula to determine the hydraulic conductivity and the storage coefficient by fitting the curve.

[0062] Use the hydraulic conductivity combined with the storage coefficient to calculate the permeability coefficient .

[0063] It should be noted that the above analysis of the permeability coefficient based on the drawdown and pumping rate data in the pumping test, using the Theis method or the Jacob method, has been widely applied and described in detail in the existing technology. The specific operation details are not elaborated in this document.

[0064] It should be understood that the permeability coefficient of a monitoring well refers to the hydraulic conductivity characteristics 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 fractures of the soil or rock. The permeability coefficient is a key hydrogeological parameter used to evaluate the velocity and direction of groundwater flow. It is defined according to Darcy's law and represents the flow velocity of groundwater under a unit hydraulic gradient. The factors affecting the soil permeability coefficient include soil particle size and arrangement, pore structure, saturation, etc. Among them, the permeability coefficient is closely related to the size, shape and arrangement of soil particles. Generally, soils with larger particles and loose arrangements (such as sand and gravel) have higher permeability coefficients; while soils with smaller particles and tight arrangements (such as clay) have lower permeability coefficients. Among them, the pore or fracture structure in the soil or rock also affects the permeability coefficient. Larger pores or fractures allow water to pass through more easily, thus increasing the permeability coefficient. Among them, under unsaturated conditions, the permeability coefficient is also affected by soil water content. Usually, the permeability coefficient of saturated soil is higher, while that of unsaturated soil is lower.

[0065] The above-mentioned permeability direction distribution analysis module is used to analyze the distribution pattern of the soil permeability direction in the foundation pit based on the permeability coefficients of each monitoring well in the pumping test. The specific analysis is as follows: Connect the monitoring wells corresponding to the geometric center points in the foundation pit boundary contour with the monitoring wells corresponding to the boundary contour points respectively to form several pointing lines.

[0066] Take the absolute value of the difference between 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 in each pointing line to obtain the absolute permeability difference of each pointing.

[0067] Respectively obtain the distances of each pointing line as the pointing distances.

[0068] Take the absolute permeability difference of each pointing line as the eigenvector to form a data matrix, where the pointing line characteristic numbers are specifically the absolute permeability 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 mentioned above are respectively denoted as 、 , represents the pointing line number, ,each pointing line 's absolute permeability difference ,pointing distance ,the constructed eigenvector ,the constructed data matrix is 。

[0070] Perform standardization processing on the data matrix so that each column of data has zero mean and unit variance.

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

[0072] Calculate the covariance matrix of the data matrix after standardization to obtain the eigenvalues and eigenvectors of the covariance matrix.

[0073] The specifically standardized data matrix mentioned above is denoted as , and the covariance matrix is denoted as , , the eigenvalues of the covariance matrix and the eigenvectors , where .

[0074] Select the first few principal components according to the size of the eigenvalues. Usually, select the principal components with a cumulative contribution rate reaching a certain threshold (such as 80% or 90%). Then project the standardized data onto the principal components to obtain the scores of each pointing line sample on the principal components, and calculate the contribution rate of each principal component at the same time.

[0075] It should be understood that the principal component contribution rate (i.e., the proportion of the 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 this principal component by the sum of all eigenvalues, which helps to understand which principal components are the most important and which are secondary.

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

[0077] Principal components with high contribution rates: These principal components explain most of the data variation and usually reflect the main trends or patterns.

[0078] Principal components with low contribution rates: These principal components explain less data variation and may contain noise or secondary trends.

[0079] By calculating the principal component contribution rate, it can be determined 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 the principal components with a cumulative contribution rate reaching a certain threshold (such as 80% or 90%) to simplify the model and reduce redundant information.

[0080] Select the trend principal components according to the contribution rate of the principal components, and calculate the standard deviation of the scores of each trend principal component. If the standard deviations of all the trend principal component scores are less than the set threshold, it is determined that the distribution pattern of the seepage direction is uniform distribution; otherwise, it is determined that the distribution pattern of the seepage direction is differential distribution.

[0081] For example, the set threshold of the standard deviation is 0.1.

[0082] It should be explained that the principal components that have the greatest influence on the data variation can be identified through the contribution rate of the principal components. These principal components reflect the main trends of the foundation pit soil seepage. For example, if there are 3 selected principal components, 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 the foundation pit soil seepage and are regarded as trend principal components.

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

[0084] It should be noted that the above analysis of the distribution pattern of the foundation pit soil seepage direction based on the seepage difference and pointing distance of the soil at different pointing line positions is carried out by using the principal component analysis method. Among them, the seepage difference of the soil at different pointing line positions reflects the difference in seepage capacity between different positions, and the pointing distance provides geometric information to help understand the spatial relationship between different monitoring points. Combining these two can provide more abundant information and can more comprehensively describe the seepage characteristics of the foundation pit soil. In actual engineering, the seepage characteristics of the foundation pit soil are often affected by various 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 the key information. In addition, the principal component scores obtained through principal component analysis can be visualized in two-dimensional or three-dimensional space to intuitively display the distribution of the foundation pit soil seepage characteristics. This not only helps engineers and technicians better understand the data, but also can 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] More preferably, the precipitation rate adjustment is implemented as follows: compare the water level height regularly collected during the precipitation operation of the monitoring well with the confined design water level height of the foundation pit construction, and at the same time compare the settlement height of each settlement observation point with the set allowable settlement height. If the settlement height of a certain settlement observation point exceeds the allowable settlement height at a certain collection time or the water level height at a certain collection time reaches the design water level height, stop the precipitation operation; otherwise, continue the precipitation operation.

[0095] In the above, the confined design water level height of the foundation pit construction is determined based on detailed engineering design documents and geological exploration reports before the foundation pit dewatering construction operation. The main purpose of the design water level height is to prevent the occurrence of heaving phenomena at the bottom of the foundation pit and avoid the instability or collapse of the foundation pit due to excessive groundwater pressure. The allowable settlement height can be obtained through geological exploration, and it 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, compare the water level height regularly collected with the water level height at the previous collection time to calculate the water level drop rate.

[0097] Perform mutation identification on the water level drop rates at each collection time for adjacent collection times. Specifically, the mutation identification can be carried out by taking the difference between the water level drop rates at adjacent collection times to obtain the water level drop rate difference, and comparing 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 it is identified that there is a mutation in the water level drop at a certain collection time, further determine the mutation direction. If the water level drop rate suddenly slows down, perform an operation to increase the precipitation rate, and the specific operation includes increasing the number of water pumps or increasing the working frequency of the pumps. If the water level drop rate suddenly speeds up, perform an operation to reduce the precipitation rate, and the specific operation includes reducing the number of water pumps or reducing the working frequency of the pumps.

[0098] Through the above method, the water level height and settlement height can be effectively monitored during the precipitation operation, and the precipitation rate can be adjusted in a timely manner based on this 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 Figure 3 As shown, the differential distribution precipitation monitoring module is used to divide the surrounding area of the foundation pit into precipitation zones when the distribution pattern of the infiltration direction of the foundation pit soil is determined to be differentially distributed, and formulate the precipitation sequence for each zone, and then perform zone-following adjustment of the precipitation rate during the precipitation operation according to the precipitation sequence.

[0100] In the improved implementation of the above solution, the specific implementation of dewatering zoning for the area around the foundation pit is as follows: Identify the similar permeability coefficients of adjacent monitoring wells among the monitoring wells except for the monitoring well corresponding to the geometric center point of the foundation pit boundary contour. Specifically, for the similarity identification, the absolute value of the difference between the permeability coefficients of adjacent monitoring wells can be compared with the preset similar permeability difference threshold. If the absolute value of the difference in the permeability coefficients of a certain pair of adjacent monitoring wells is less than or equal to the similar permeability difference threshold, it is identified that the permeability coefficients of the adjacent monitoring wells are similar. If the permeability coefficients of a certain pair of adjacent monitoring wells are similar, then these two monitoring wells and the area where they are located are regarded as a dewatering area. If the permeability coefficients of a certain pair of adjacent monitoring wells are not similar, the areas where these two monitoring wells are located are divided into two independent dewatering areas.

[0101] In the above, the dewatering area is divided based on the permeability coefficients in the direction where the adjacent monitoring wells are located, which can achieve more refined and efficient dewatering management. Since there are significant differences in the soil permeability characteristics of different areas, through zoned dewatering, the pumping rate and strategy can be adjusted according to the specific permeability coefficient of each area to ensure that the dewatering effect is more uniform. In addition, by independently controlling different areas, it is possible to prevent the sharp drop of the groundwater level caused by excessive pumping and ensure the safety of the foundation pit and the surrounding environment.

[0102] In a further improved implementation, the following operations are carried out to formulate the dewatering sequence for each zone: Obtain the permeability coefficients of each dewatering area, and thus arrange the dewatering areas in descending order of permeability coefficient to obtain the dewatering sequence of the dewatering areas.

[0103] In the above, since there are cases where there are multiple monitoring wells in a certain dewatering area, when obtaining the permeability coefficient corresponding to the dewatering area to which the monitoring wells corresponding to multiple similar permeability coefficients belong, the average value of the permeability coefficients of different monitoring wells in the dewatering area can be taken to obtain the permeability coefficient of the dewatering area.

[0104] It should be understood that usually, the groundwater level in the area with a high permeability coefficient changes relatively fast. Therefore, the dewatering operation should be carried out preferentially, which can avoid problems such as soil instability caused by the rapid drop of the local water level during the dewatering process.

[0105] In a further improved implementation, the zoned follow-up adjustment of the dewatering speed is as follows: First, select the dewatering area ranked first according to the dewatering sequence of the dewatering areas, and select a representative monitoring well (such as the monitoring well corresponding to the geometric center point) in this dewatering area.

[0106] While carrying out the dewatering operation in the representative monitoring well of the first dewatering area, synchronously carry out the foundation settlement detection and the water level height measurement.

[0107] Adjust the precipitation rate of the first precipitation area according to the real-time monitored foundation settlement data and water level height data. The specific adjustment strategy can be similarly referred to the precipitation rate adjustment of the representative monitoring wells under uniform distribution, and record the direction (increase or decrease) and the number of adjustments each time.

[0108] Judge whether the precipitation rate adjustment is frequent based on the number of adjustments. If it is not frequent, keep the final precipitation rate of the first precipitation area as the initial precipitation rate of the next precipitation area. If it is frequent, further analyze the adjustment tendency. Specifically, by counting the proportion of the number of increase and decrease adjustments, extract the adjustment direction with a larger proportion. If the adjustment tendency is to increase the precipitation rate, the initial precipitation rate of the next precipitation area is higher than the final precipitation rate of the first precipitation area according to a set ratio (such as 5%-10%). If the adjustment tendency is to decrease the precipitation rate, the initial precipitation rate of the next precipitation area is lower than the final precipitation rate of the first precipitation area according to a set ratio, until the precipitation rate adjustment of the last precipitation area is carried out.

[0109] In the above example, assume 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 3 adjustments are made during the operation of precipitation area A, among which 2 times the precipitation rate is increased and 1 time it is decreased. Since the number of adjustments is large, it is judged that the adjustment is too frequent. Further analyze that the adjustment direction mainly tends to increase the precipitation rate. The initial precipitation rate of the next precipitation area B should be increased by a certain proportion (such as 5%-10%) based on the final precipitation rate of area A.

[0110] Through the above method, the water level height and settlement height can be effectively monitored during the precipitation operation, and the precipitation rate of the subsequent precipitation areas can be adjusted in a timely manner based on this to ensure the construction safety and efficiency.

[0111] The above content is only an example and explanation of the structure of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined by the present invention, they should 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; The pumping test implementation module implements the pumping test in the deployed monitoring wells and conducts the permeability analysis of each monitoring well; 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 using the groundwater level and the initial groundwater level; After reaching the predetermined pumping time, the pump is stopped, and the permeability coefficient of each monitoring well is analyzed using the water level drawdown and pumping volume data at different time points; The infiltration direction distribution determination module determines the infiltration direction distribution pattern of the foundation pit soil based on the infiltration analysis results 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 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 the pointing line is 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; Uniformly distributed precipitation monitoring module: 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 precipitation operations, and the water level height and foundation settlement are detected during the precipitation operation, and the precipitation speed is adjusted 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.

4. 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.

5. 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.

6. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 5, 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.

7. 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.

8. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 7, 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.

9. A foundation pit confined water dewatering dynamic monitoring system as claimed in claim 6, 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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