A method, device and system for controlling dewatering in foundation pit engineering

Abstract

This application relates to the field of civil engineering technology, and provides a method, device, and system for controlling dewatering in foundation pit engineering. The method includes: obtaining soil layer parameters of the foundation pit; constructing a mathematical model of the optimal wellpoint spacing L based on the design drawdown depth, design dewatering time, and safety factor; deploying multiple independently controllable manholes according to the optimal wellpoint spacing L; wherein each manhole is equipped with a variable frequency submersible pump; controlling the working state of the variable frequency submersible pump at each manhole to adjust the current dewatering intensity Q(t) of the foundation pit engineering so that the water level of the foundation pit engineering reaches the design dewatering level; thereby solving the problem of unreasonable wellpoint spacing layout in existing systems.

Description

Technical Field

[0001] This application belongs to the field of civil engineering technology, and in particular relates to a method, device and system for controlling dewatering in foundation pit engineering. Background Technology

[0002] In foundation pit construction, wellpoint dewatering is a common technique for controlling groundwater levels. This technique involves installing a series of wells around the foundation pit and using submersible pumps to continuously pump water, forming a dewatering funnel and lowering the groundwater level below the bottom of the pit, thus ensuring dry construction conditions. The spacing between wellpoints is usually determined based on engineering experience or simplified hydrogeological calculation formulas. During dewatering, the pumps generally operate at a constant frequency to maintain a stable pumping flow rate.

[0003] However, existing well dewatering technology has the following problems in application: the spacing between well points is mostly determined by engineering experience, and the comprehensive influence of multiple factors such as soil permeability, aquifer thickness, and dewatering time is not fully considered. In heterogeneous foundations, the well points may be too dense, leading to increased costs, or too sparse, leading to insufficient dewatering effect. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a method, device and system for controlling dewatering in foundation pit engineering, which can solve the problem of unreasonable well point spacing layout in the existing system.

[0005] A first aspect of this application provides a method for controlling dewatering in foundation pit engineering, the method comprising:

[0006] Obtain the soil layer parameters of the foundation pit, wherein the soil layer parameters include at least: soil permeability coefficient. Aquifer thickness Radius of influence well point radius Coefficient of soil uniformity Groundwater seepage rate and initial groundwater level ;

[0007] According to the design drawdown Design precipitation time and safety factor The mathematical model for constructing the optimal well point spacing L is as follows:

[0008]

[0009] in, This indicates the optimal wellpoint spacing, in meters (m). This represents the soil permeability coefficient, expressed in m / d. This indicates the thickness of the aquifer, in meters (m). This indicates the design precipitation time, expressed in days (d). This indicates the design drawdown, in meters (m). The safety factor is dimensionless. Indicates the radius of influence, in meters (m). This represents the well point radius, in meters (m). This represents the soil unevenness coefficient, which is dimensionless. This indicates the groundwater seepage velocity, expressed in m / d. Represents the natural constant;

[0010] Multiple independently controllable tubular well points are deployed according to the optimal well point spacing L; each of the tubular well points is equipped with a variable frequency submersible pump;

[0011] The operating status of the variable frequency submersible pump equipped at each of the aforementioned well points is controlled, thereby adjusting the current dewatering intensity Q(t) of the foundation pit project so that the water level of the foundation pit project reaches the design dewatering level. .

[0012] In one embodiment, adjusting the current precipitation intensity Q(t) of the foundation pit project includes:

[0013] The mathematical model for the current precipitation intensity Q(t) is as follows:

[0014]

[0015] in, This indicates the initial precipitation intensity, expressed in m³ / h. This represents the precipitation regulation coefficient, which is dimensionless. This represents the measured groundwater level at time t, in meters (m). This indicates the design precipitation level, in meters (m). This indicates the initial groundwater level, in meters (m). The value represents the precipitation attenuation factor, which is dimensionless; t represents the time since precipitation occurred, in hours. This represents the total designed precipitation time, in hours, and T = 24. .

[0016] In one embodiment, the initial precipitation intensity The calculation methods include:

[0017] The initial precipitation intensity is constructed based on the minimum horizontal width B of the foundation pit. The mathematical model is as follows:

[0018]

[0019] Where B represents the minimum horizontal width of the excavation pit, in meters (m); for rectangular excavations, B is the length of the shorter side; for irregular excavations, B is the minimum horizontal distance between any two points.

[0020] In one embodiment, the mathematical model for constructing the optimal wellpoint spacing L also includes

[0021] The mathematical model for constructing the safety factor S is as follows:

[0022]

[0023] Where S represents the safety factor, which is dimensionless; Represents the hyperbolic tangent function

[0024] In one embodiment, the precipitation regulation coefficient The calculation method is as follows

[0025]

[0026] Where k represents the soil permeability coefficient.

[0027] In one embodiment, the step of deploying multiple independently controllable well points according to the optimal well point spacing L includes:

[0028] When laying out the well points, the well points are arranged in a quincunx or rectangular pattern, and the spacing between well points at the corners of the foundation pit is set to 0.6 to 0.8 times the optimal spacing L of the well points.

[0029] In one embodiment, adjusting the current precipitation intensity Q(t) of the foundation pit project to make the water level of the foundation pit project reach the design precipitation level includes:

[0030] When the calculated Q(t) exceeds 1.2 times the rated flow of the water pump or is less than 0.3 times the rated flow of the water pump, an early warning signal is generated and the precipitation intensity of the previous moment is maintained.

[0031] In one embodiment, the precipitation attenuation factor γ ranges from 0.95 to 0.99, and is determined based on the ratio of the precipitation influence radius to the pit size; the larger the ratio, the larger the value of γ.

[0032] A second aspect of this application provides a dewatering control device for foundation pit engineering, the foundation pit engineering dewatering control device comprising:

[0033] Acquisition Unit: Used to acquire soil parameters of the foundation pit, wherein the soil parameters include at least: soil permeability coefficient. Aquifer thickness Radius of influence well point radius Coefficient of soil uniformity Groundwater seepage rate and initial groundwater level ;

[0034] Calculation unit: used to calculate the design drawdown. Design precipitation time and safety factor The mathematical model for constructing the optimal well point spacing L is as follows:

[0035]

[0036] in, This indicates the optimal wellpoint spacing, in meters (m). This represents the soil permeability coefficient, expressed in m / d. This indicates the thickness of the aquifer, in meters (m). This indicates the design precipitation time, expressed in days (d). This indicates the design drawdown, in meters (m). The safety factor is dimensionless. Indicates the radius of influence, in meters (m). This represents the well point radius, in meters (m). This represents the soil unevenness coefficient, which is dimensionless. This indicates the groundwater seepage velocity, expressed in m / d. Represents the natural constant;

[0037] Deployment unit: used to deploy multiple independently controllable tubular well points according to the optimal spacing L of the well points; wherein each of the tubular well points is equipped with a variable frequency submersible pump;

[0038] Control unit: Used to control the operating status of the variable frequency submersible pump equipped at each of the well points, thereby adjusting the current dewatering intensity Q(t) of the foundation pit project so that the water level of the foundation pit project reaches the design dewatering level. .

[0039] A third aspect of this application provides a dewatering control system for foundation pit engineering, including the foundation pit engineering dewatering control device as described above.

[0040] Compared with existing technologies, this application has at least the following beneficial effects: This invention achieves a scientific and quantitative design of well point spacing. Specifically, by determining key parameters such as soil permeability coefficient k, aquifer thickness H, radius of influence R, soil heterogeneity coefficient α, and groundwater seepage velocity through field tests, the optimal well point spacing L is comprehensively calculated, and the well points are arranged according to the calculated spacing. This scheme changes the traditional method of determining well point spacing based on engineering experience, incorporating multiple factors such as soil seepage characteristics, precipitation time requirements, and safety reserve needs into a unified calculation model, so that the well point layout is accurately matched with the actual hydrogeological conditions of the site, avoiding the problems of over-density waste or over-sparse failure caused by experience-based well placement. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram illustrating the steps of a dewatering control method for foundation pit engineering according to an embodiment of this application;

[0043] Figure 2 This is a schematic diagram illustrating the error rate between the patented method and existing methods provided in one embodiment of this application;

[0044] Figure 3 This is a schematic diagram of a foundation pit engineering dewatering control device provided in one embodiment of this application. Detailed Implementation

[0045] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0046] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] In foundation pit construction, wellpoint dewatering is a common technique for controlling groundwater levels. This technique involves installing a series of wells around the foundation pit and using submersible pumps to continuously pump water, forming a dewatering funnel and lowering the groundwater level below the bottom of the pit, thus ensuring dry construction conditions. The spacing between wellpoints is usually determined based on engineering experience or simplified hydrogeological calculation formulas. During dewatering, the pumps generally operate at a constant frequency to maintain a stable pumping flow rate.

[0048] However, existing well dewatering technology has the following problems in application: the spacing between well points is mostly determined by engineering experience, and the comprehensive influence of multiple factors such as soil permeability, aquifer thickness, and dewatering time is not fully considered. In heterogeneous foundations, the well points may be too dense, leading to increased costs, or too sparse, leading to insufficient dewatering effect.

[0049] To solve the above technical problems, refer to Figure 1 As shown in the figure, this application provides a method for controlling dewatering in foundation pit engineering, the method including steps S100 to S400.

[0050] Step S100: Obtain the soil parameters of the foundation pit. The soil parameters shall include at least the soil permeability coefficient. Aquifer thickness Radius of influence well point radius Coefficient of soil uniformity Groundwater seepage rate and initial groundwater level ;

[0051] Step S200: Based on the design drawdown Design precipitation time and safety factor The mathematical model for constructing the optimal well point spacing L is as follows:

[0052]

[0053] in, This indicates the optimal spacing between well points, which is the horizontal distance between two adjacent precipitation well points, in meters. This represents the soil permeability coefficient, expressed in m / d. This indicates the thickness of the aquifer, which is the vertical distance from below the groundwater level to the impermeable base plate, in meters (m). This indicates the design precipitation time, which is the time required to reach the design precipitation depth, expressed in days (d). This indicates the design drawdown, which is the time required to reach the design drawdown depth. = - The unit is meters (m). The safety factor is dimensionless. The radius of influence, i.e. the radius of the area affected by precipitation, can be determined through field tests or empirical formulas, and is measured in meters (m). This indicates the well point radius, which is the diameter of the well, in meters (m). This represents the soil unevenness coefficient, with a value ranging from 0.1 to 0.5, and is dimensionless. This indicates the groundwater seepage velocity, expressed in m / d. Represents the natural constant;

[0054] Step S300: Deploy multiple independently controllable tubular well points according to the optimal well point spacing L; wherein, each tubular well point is equipped with a variable frequency submersible pump;

[0055] Step S400: Control the operating status of the variable frequency submersible pump at each well point, thereby adjusting the current dewatering intensity Q(t) of the foundation pit project so that the water level of the foundation pit project reaches the design dewatering level. .

[0056] Specifically, the methods for obtaining soil parameters are as follows: the permeability coefficient k and the radius of influence R are determined through on-site pumping tests; the aquifer thickness H and the initial groundwater level are determined through borehole exploration. Well point radius The actual selected borehole diameter; the coefficient of uniformity was calculated through particle size analysis of the borehole soil samples. According to Darcy's law, the seepage velocity is calculated from the permeability coefficient k and the hydraulic gradient. .

[0057] In this embodiment, the mathematical model for the optimal wellpoint spacing L is the core calculation step. This model is an improvement on the Jubuy formula, incorporating a design precipitation time factor. and soil unevenness correction item The design drawdown is among them. From the initial water level With the design precipitation level Determine the difference; design precipitation time The optimal wellpoint spacing L is calculated by substituting the measured and design parameters into the model. The exponential correction term in this model... This reflects the cumulative impact of soil heterogeneity and seepage velocity on precipitation effects. When the soil heterogeneity coefficient... Larger or seepage velocity When the value is high, this value decreases, allowing the calculation interval to be appropriately shortened to enhance precipitation capacity.

[0058] In this embodiment, manholes are installed around the foundation pit according to the calculated value L. For example, they are evenly spaced at intervals of L along both the long and short sides of a rectangular foundation pit, with the spacing increased at corners. A variable frequency submersible pump is installed in each manhole. The pump's motor frequency is adjusted by a frequency converter, thereby changing the pump speed and pumping flow rate.

[0059] In this embodiment, the specific method for controlling the operating state of the variable frequency submersible pump is as follows: the control system sets the initial operating frequency and collects data from the water level observation well in real time. When monitoring the water level... Higher than the design water level When the water level approaches or reaches the specified value, the system increases the inverter frequency, thereby increasing the pump speed and the water intensity Q(t); when the water level approaches or reaches the specified value... When the water level is low, reduce the frequency and intensity of rainfall; when the water level is below... In such cases, the frequency will be further reduced or operations will be suspended to prevent excessive rainfall. Through this closed-loop regulation, the water level will ultimately be stabilized at [a certain level]. .

[0060] In this embodiment, the working principle of the method is as follows: the hydrogeological conditions of the site are accurately grasped by measured parameters, and the well point spacing is quantitatively designed using a mathematical model that includes multi-factor correction, so that the well point layout is accurately matched with the engineering requirements; then, a closed-loop control system is formed by variable frequency water pumps and water level monitoring to realize the dynamic adjustment of precipitation intensity.

[0061] In this embodiment, the well spacing is calculated based on measured data and scientific models, avoiding the blindness of experience-based well placement, ensuring both the precipitation effect and avoiding waste; the variable frequency closed-loop control realizes dynamic response to precipitation intensity, effectively preventing excessive precipitation from causing surrounding subsidence or insufficient precipitation from delaying the construction period, significantly improving the accuracy and environmental friendliness of precipitation control.

[0062] In one embodiment, adjusting the current precipitation intensity Q(t) of the foundation pit project includes:

[0063] The mathematical model for the current precipitation intensity Q(t) is as follows:

[0064]

[0065] in, This indicates the initial precipitation intensity, expressed in m³ / h. This represents the precipitation regulation coefficient, which is dimensionless. This represents the measured groundwater level at time t, in meters (m). This indicates the design precipitation level, in meters (m). This indicates the initial groundwater level, in meters (m). The value represents the precipitation attenuation factor, which is dimensionless; t represents the time since precipitation occurred, in hours. This represents the total designed precipitation time, in hours, and T = 24. .

[0066] Specifically, in this embodiment, the mathematical model is constructed based on the principle of feedback control. The initial precipitation intensity... The precipitation regulation coefficient can be pre-calculated based on the measured soil parameters and well point layout. For example, the total inflow can be estimated using the Dubuis formula and then divided by the number of well points. The correction range used to control the water level deviation on the rainfall intensity is usually between 0.3 and 0.7. It can be selected according to the permeability of the soil layer. A smaller value is used for soil layers with high permeability, and a larger value is used for soil layers with low permeability. The water level is obtained in real time by a water level sensor; the designed precipitation water level is... The initial groundwater level is determined based on the bottom elevation of the foundation pit and the safety freeboard (generally taken as 0.5~1.5m). Precipitation attenuation factor, measured by field tests. The value reflecting the impact of changes in the seepage field during the later stages of precipitation on precipitation efficiency is typically taken as 0.95~0.99, and its value can be determined based on the ratio of the radius of influence to the size of the foundation pit; the precipitation time t is started from the beginning of precipitation; the total design precipitation time... With design precipitation time Satisfying T = 24· That is, converting the number of days into the number of hours.

[0067] In this embodiment, the working principle of the mathematical model is: when the measured water level Higher than the design water level When, deviation term For positive, Greater than The intensity of precipitation increases to accelerate the drop in water level; when Below When, deviation term Negative, Less than The intensity of rainfall is reduced to prevent excessive rainfall; when the water level approaches the design value, the deviation term approaches zero. Return to Nearby. Meanwhile, precipitation attenuation factor. Gradually decrease over time (if) (negative) or increase (if) (positive), here it is usually taken as The negative value reflects the reduced efficiency of subsequent precipitation, causing the precipitation intensity to decrease slowly over time, which conforms to the actual seepage law. Using this formula, the control system can calculate and adjust the operating frequency of each variable frequency submersible pump in real time, achieving dynamic closed-loop control of precipitation intensity.

[0068] In this embodiment, the precipitation intensity can be automatically corrected according to real-time water level changes, avoiding the lag and inaccuracy of manual adjustment, effectively suppressing water level overshoot, and enabling the groundwater level to reach the design target smoothly and quickly. At the same time, it minimizes the impact of excessive precipitation on the surrounding environment and improves the safety and economy of the precipitation project.

[0069] In one embodiment, the initial precipitation intensity The calculation methods include:

[0070] The initial precipitation intensity is determined based on the minimum horizontal width B of the foundation pit. The mathematical model is as follows:

[0071]

[0072] Where B represents the minimum horizontal width of the foundation pit, in meters; for rectangular foundation pits, B is the length of the shorter side; for irregular foundation pits, B is the minimum horizontal distance between any two points.

[0073] Specifically, in this embodiment, the mathematical model is constructed based on the Dubouine steady-flow theory and incorporates a correction for the pit width. The parameters in the formula have the following meanings: 𝑘 is the measured soil permeability coefficient (m / d), and 𝐻 is the aquifer thickness (m). Let be the design drawdown (m), and be the radius of influence (m). Let be the well point radius (m), 𝐿 be the calculated optimal well point spacing (m), and 𝐵 be the minimum horizontal width of the foundation pit (m).

[0074] In this embodiment, the minimum horizontal width of the foundation pit The determination of B is crucial to this calculation method. For a regular rectangular foundation pit, such as a case with a length of 120m and a width of 25m, B is taken as the shorter side length of 25m. This is because the seepage path of groundwater into the foundation pit is shortest along the shorter side, resulting in the largest hydraulic gradient. This is the most unfavorable location for dewatering design, and using this as a control dimension ensures effective dewatering at the weakest point of the foundation pit. For irregularly shaped foundation pits, such as L-shaped or irregularly shaped pits, B is taken as the minimum horizontal distance between any two points in the foundation pit. For example, this value can be determined by measuring the two closest points on the foundation pit outline drawing. In actual engineering, the value of B can be obtained directly from the foundation pit design drawings or through on-site measurement.

[0075] The physical meaning of this formula is: the front part This is the total inflow of the foundation pit under boundaryless conditions calculated based on the Jubuy formula, reflecting the inflow capacity determined by the site's hydrogeological conditions; the latter part is multiplied by a coefficient. This involves distributing the total inflow to each well point and taking into account the correction for the pit width. When the pit width B is small, the coefficient is large, indicating that a narrow pit requires a stronger initial precipitation intensity to cope with a steeper hydraulic gradient; when B is large, the coefficient is small, and the initial precipitation intensity is correspondingly reduced.

[0076] In this embodiment, the working principle of the calculation method is as follows: by comprehensively considering the site's hydrogeological conditions (k, H, R) and the geometric characteristics of the foundation pit (L, B), the initial precipitation intensity that matches the actual engineering situation is calculated. This value serves as the basis for subsequent dynamic precipitation intensity. The adjusted benchmark ensures that the entire precipitation process is within a reasonable pumping intensity range from the initial stage.

[0077] In this embodiment, the impact of the pit shape and size on precipitation is incorporated into the quantitative calculation, avoiding the blind estimation of initial pumping intensity based solely on inflow volume in traditional methods. Taking a rectangular pit as an example, the width of the shorter side is taken as B, ensuring that the calculation results prioritize the precipitation needs of the most unfavorable areas, effectively preventing precipitation dead zones or insufficient local precipitation caused by the pit shape. For irregular pits, the minimum horizontal distance is taken as B, similarly ensuring coverage of the areas with the most stringent precipitation control requirements. This method significantly improves the scientific rigor and relevance of the initial precipitation intensity setting, providing a precise benchmark value for subsequent dynamic adjustments.

[0078] In one embodiment, the mathematical model for constructing the optimal wellpoint spacing L also includes

[0079] The mathematical model for constructing the safety factor S is as follows:

[0080]

[0081] Where S represents the safety factor, which is dimensionless; This represents the hyperbolic tangent function.

[0082] Specifically, the safety factor S is no longer determined by the engineer's subjective judgment, but is automatically generated based entirely on the measured soil parameters at the site, eliminating the arbitrariness and uncertainty of human-selected values. For homogeneous, highly permeable, and favorable strata, the calculated S is close to 1.2, making the wellpoint spacing calculation result economical and reasonable. For heterogeneous, high-risk strata with complex seepage conditions, the calculated S approaches 1.8, automatically increasing the safety reserve and effectively ensuring the safety of dewatering projects. This method significantly improves the scientific rigor and reliability of the wellpoint spacing calculation in claim 1, achieving a balance between safety and economy.

[0083] In one embodiment, the precipitation regulation coefficient The calculation method is as follows

[0084]

[0085] Where k represents the soil permeability coefficient.

[0086] Specifically, this calculation method is based on the influence of soil permeability on precipitation response rate. The specific value selection rules are as follows:

[0087] In this embodiment, when the soil permeability coefficient This indicates that the soil layer is weakly permeable (such as silty clay or clay). In these types of strata, groundwater seepage is slow, and the response of water level changes to rainfall intensity exhibits a significant lag. Therefore, a larger adjustment coefficient β=0.7 is needed to enhance the correction range of rainfall intensity to water level deviation, thereby overcoming the seepage lag effect and ensuring the continuous advancement of rainfall. For example, a pumping test at a silty clay site measured... If so, then we can directly take β=0.7.

[0088] In this embodiment, when the soil permeability coefficient This indicates that the soil layer is highly permeable (such as coarse sand or gravel). In these strata, groundwater flows rapidly, and the water level is very sensitive to changes in rainfall intensity; even a small adjustment can cause a rapid water level response. Therefore, a small adjustment coefficient β=0.3 is used to prevent excessive adjustment from causing large fluctuations or even overshooting of the water level. For example, at a sandy site, the measured... If so, then we can directly take β=0.3.

[0089] In this embodiment, when the soil permeability coefficient is between When the value is between 0 and 1, it indicates that the soil layer has moderate permeability (such as fine sand or silt). In this case, a linear interpolation formula is used to calculate: β = The formula outputs 0.7 when k=1 and 0.3 when k=10, decreasing linearly as k increases. For example, in a fine sand field, k=4.5m / d is measured. Substituting this into the calculation: β=0.7−0.4×(4.5−1) / 9=0.7−0.4×3.5 / 9=0.7−0.4×0.389=0.7−0.156=0.544, so we take β=0.54.

[0090] In this embodiment, the beneficial effect of using this calculation method is that it further refines the value of β from the empirical range (0.3~0.7) into a quantitative expression directly related to the soil permeability coefficient k, eliminating the subjectivity of manually selecting the adjustment coefficient. For strata with different permeability, this formula automatically matches the most suitable adjustment intensity: strong adjustment is used for weakly permeable layers to ensure the progress of precipitation, weak adjustment is used for highly permeable layers to ensure system stability, and a continuous transition is used for moderately permeable layers. This enables the dynamic precipitation intensity model to adapt to different site conditions, significantly improving the universality and robustness of the precipitation control system, and ensuring smooth and efficient water level regulation in any soil layer.

[0091] In one embodiment, deploying multiple independently controllable well points according to the optimal well point spacing L includes:

[0092] When laying out the well points, the well points are arranged in a quincunx or rectangular pattern, and the spacing between well points at the corners of the foundation pit is set to 0.6 to 0.8 times the optimal spacing L of the well points.

[0093] Specifically, the implementation method of well point layout depends on the planar shape of the foundation pit. For rectangular or elongated foundation pits, a rectangular layout is usually adopted. In practice, well points are arranged in rows and columns at intervals L along both the long and short sides of the foundation pit, forming a regular grid. For example, for a foundation pit that is 120m long and 25m wide, if the calculated L = 8.5m, then 3 rows can be arranged on the 25m wide short side (25 / 8.5≈2.9, take 3 rows), and 14 columns can be arranged on the 120m long side (120 / 8.5≈14.1, take 14 columns), with the well positions falling at the grid intersections.

[0094] In this embodiment, for foundation pits that are approximately square or require enhanced dewatering, a staggered arrangement can be used. This arrangement staggers the well points in adjacent rows by half a spacing, meaning the well points in the second row are located in the middle of the two well points in the first row. The construction layout method is as follows: first, lay out the first row of well points around the perimeter of the foundation pit at a spacing L, and then... The second row is arranged at a position of ×L (approximately 0.87L), with the well points of the second row aligned with the midpoint of the spacing of the first row. The quincunx arrangement allows the drawdown funnels to overlap more evenly, forming a smoother drawdown surface.

[0095] In this embodiment, the groundwater seepage at the corner of the foundation pit exhibits significant two-dimensional flow characteristics, with the water converging in two directions and a large hydraulic gradient, making it a weak point in dewatering control. Therefore, it is necessary to densify the number of well points at the corner. Specifically, on the two sides of each corner (i.e., the inner corner) of the foundation pit, starting from the corner vertex, the distance between the first well point and the corner is set to 0.6L~0.8L, for example, 0.7L. Taking L=8.5m as an example, the first well point at the corner is set approximately 5.95m from the corner vertex, and the remaining well points continue to be arranged at the normal spacing L. This densification coefficient can be selected within this range based on the depth of the foundation pit and the soil conditions. The deeper the foundation pit and the stronger the soil permeability, the closer the value should be to the lower limit of 0.6 to enhance the densification effect.

[0096] In this embodiment, the dewatering funnels of each well point are superimposed by a reasonable planar arrangement (rectangular or quincunx shape) to form a continuous dewatering surface covering the entire foundation pit; by increasing the density of well points at the corners (0.6~0.8L), the pumping capacity of this special part is enhanced to offset the water level rise caused by two-dimensional seepage, and to ensure that the groundwater level at the edge of the foundation pit and the corners can also drop to the design elevation simultaneously.

[0097] In this embodiment, the rectangular layout is simple and regular, facilitating construction layout and pipeline laying; the quincunx layout makes the dewatering effect more uniform and reduces dewatering blind spots. The denser layout at the corners effectively solves the problem of dewatering lag at corners caused by conventional equidistant well layouts, ensuring that the water level at each point on the foundation pit outline drops synchronously, avoiding the risk of slope instability or quicksand caused by excessively high local water levels, and improving the reliability and uniformity of the overall dewatering system.

[0098] In one embodiment, adjusting the current precipitation intensity Q(t) of the foundation pit project to bring the water level of the foundation pit project to the design precipitation level includes:

[0099] When the calculated Q(t) exceeds 1.2 times the rated flow of the water pump or is less than 0.3 times the rated flow of the water pump, an early warning signal is generated and the precipitation intensity of the previous moment is maintained.

[0100] Specifically, an "actuator" module is set up in the software logic of the control system. After receiving a new Q(t) calculated value, this module first calls the preset rated flow rate parameter of the water pump and performs a threshold comparison. Only when the calculated value falls within the safe range (0.3 times the rated flow rate to 1.2 times the rated flow rate) is the calculated value converted into the corresponding frequency inverter command (e.g., through the flow-frequency conversion curve) and output to the water pump for execution. If the calculated value falls outside the safe range, an alarm is triggered, and the issuance of new commands is prevented, so that the water pump continues to operate at the frequency of the previous cycle.

[0101] In this embodiment, overload or underload operation of the equipment caused by abnormal mathematical model calculations or sensor data fluctuations is effectively avoided, protecting the motor life of the variable frequency submersible pump and preventing rainfall interruption due to pump damage. Simultaneously, the generation of early warning signals can promptly notify engineering management personnel to check the system status and identify the causes of exceeding limits (such as sensor failure, sudden water level changes, etc.), improving the robustness and operational safety of the entire rainfall control system and ensuring that the rainfall process proceeds within a controllable and safe range.

[0102] In one embodiment, the precipitation attenuation factor γ ranges from 0.95 to 0.99, and is determined based on the ratio of the precipitation influence radius to the pit size; the larger the ratio, the larger the value of γ.

[0103] In this embodiment, the radius of influence of precipitation The pit size B reflects the extent of the pumping impact, and determines the steepness of the dewatering funnel. When When the value is much greater than B, the precipitation funnel is gentle. As precipitation continues, the groundwater recharge path gradually lengthens, and the seepage resistance increases. This leads to a gradual decrease in the dewatering efficiency at the same pumping power. Therefore, a larger γ (close to 0.99) is required to... By gradually decreasing the value of γ over time and linking it to the geometric characteristics and influence radius of the foundation pit, the model bias that might result from a fixed value is avoided. For large-scale precipitation (with a high R / B ratio), a larger value of γ is used, enabling the dynamic model to accurately reflect the flow compensation required for increased seepage resistance in the later stages and maintain water level stability. For small-scale precipitation (with a low R / B ratio), a smaller value of γ is used to avoid overcompensation leading to water level fluctuations. This method enhances the adaptability and prediction accuracy of the precipitation model.

[0104] In one embodiment, a subway station foundation pit is 120m long, 25m wide, and 15.5m deep. The site soil consists of alternating layers of silty clay and fine sand, and the groundwater level is 2.5m deep. The dewatering design is carried out using the system of this invention.

[0105] Based on on-site pumping tests, the following parameters were determined: permeability coefficient k = 2.8 m / d, aquifer thickness H = 18.5 m, radius of influence R = 150 m, and design wellpoint radius. =0.15m, soil unevenness coefficient is 0.25, groundwater seepage velocity =0.35m / d, initial groundwater level =2.5m. Based on the pit depth of 15.5m, a safety freeboard of 1.0m is taken, and the design dewatering level is... = -14.0m (with the ground level as 0, the bottom of the pit as -13.0m, and then lowered to 1.0m below the pit bottom), then the design drawdown is... = - = 2.5m -(-14.0m) = 16.5m. However, for the sake of simplifying the calculation, this example uses the design drawdown. =13.0m (corresponding to) =-10.5m, that is, 2.5m above the bottom of the pit), design precipitation time = 10d. Total design dewatering time T = 24 × 10 = 240h. Minimum width of the foundation pit B = 25m (short side length).

[0106] Further, the safety factor S = 1.22 is calculated using the above formula; substituting this into the formula for well point spacing L, L ≈ 8.5m is calculated. Based on the soil permeability coefficient k = 2.8m / d, which is between 1 m / d and 10 m / d, the following calculation is performed using the linear interpolation formula: =0.7−0.4×2.8−110−1=0.7−0.4×1.89=0.7−0.4×0.2=0.7−0.08=0.62β=0.7−0.4×10−12.8−1=0.7−0.4×91.8=0.7−0.4×0.2=0.7−0.08=0.62.

[0107] Calculate the initial precipitation intensity =15 m³ / h; set attenuation factor γ=0.97. During the precipitation process, the monitoring system collects water level data in real time, and the control unit updates the precipitation intensity every 2 hours. On the 5th day of precipitation (t=120h), the measured water level h(t)= -5.2m, which is 5.3m away from the design water level h_d = -10.5m. The calculated deviation is... ≈0.408, so Q(t) = 15 × [1 + 0.62 × 0.408] × 0.97^(120 / 240) = 15 × [1 + 0.253] × 0.985 ≈ 15 × 1.253 × 0.985 ≈ 18.5 m³ / h; when the precipitation reaches the 8th day (t = 192 h), the measured water level h(t) = -10.1 m, with a deviation of... ≈0.0308, so Q(t) = 15 × [1 + 0.62 × 0.0308] × 0.97^(192 / 240) = 15 × [1 + 0.0191] × 0.976 ≈ 15 × 1.0191 × 0.976 ≈ 14.9 m³ / h. When the water level reaches the design precipitation level... After reaching -10.5m, the system enters the maintenance phase, continuing to calculate and adjust the precipitation intensity Q(t) in real time. Since h(t) ≈ h_d at this point, in the formula... Approaching 0, therefore Q(t)≈ This means that the water level gradually decreases over time, causing it to fluctuate slightly around the design value, thus keeping the foundation pit dry while avoiding excessive precipitation. No excessive precipitation occurred throughout the entire process, and the settlement monitoring values ​​of surrounding buildings were all within the allowable range.

[0108] In an experiment, such as Figure 2 As shown in the figure, simulation experiments were conducted in different foundation pits using the method of this patent. Twenty foundation pit dewatering control experiments were carried out. As can be seen from the figure, the average error value of the dewatering using the method of this patent is 1.113%, the variance is 1.104, and the maximum error is 2.326%. Therefore, the method of this patent is stable.

[0109] This application embodiment also provides a dewatering control device for foundation pit engineering, the foundation pit engineering dewatering control device includes:

[0110] Acquisition Unit: Used to acquire soil parameters of the foundation pit. These soil parameters include at least the soil permeability coefficient. Aquifer thickness Radius of influence well point radius Coefficient of soil uniformity Groundwater seepage rate and initial groundwater level ;

[0111] Calculation unit: used to calculate the design drawdown. Design precipitation time and safety factor The mathematical model for constructing the optimal well point spacing L is as follows:

[0112]

[0113] in, This indicates the optimal wellpoint spacing, in meters (m). This represents the soil permeability coefficient, expressed in m / d. This indicates the thickness of the aquifer, in meters (m). This indicates the design precipitation time, expressed in days (d). This indicates the design drawdown, in meters (m). The safety factor is dimensionless. Indicates the radius of influence, in meters (m). This represents the well point radius, in meters (m). This represents the soil unevenness coefficient, which is dimensionless. This indicates the groundwater seepage velocity, expressed in m / d. Represents the natural constant;

[0114] Deployment unit: used to deploy multiple independently controllable tubular well points according to the optimal well point spacing L; each tubular well point is equipped with a variable frequency submersible pump;

[0115] Control unit: Used to control the operating status of the variable frequency submersible pump at each well point, thereby adjusting the current dewatering intensity Q(t) of the foundation pit project so that the water level in the foundation pit project reaches the design dewatering level. .

[0116] In this embodiment, the acquisition unit inputs the site's hydrogeological parameters, the calculation unit automatically calculates the optimal wellpoint spacing based on a mathematical model, the deployment unit completes the on-site wellpoint construction according to this spacing, and finally, the control unit achieves dynamic closed-loop control of precipitation intensity through real-time monitoring and frequency conversion adjustment, ensuring that the groundwater level accurately reaches and is maintained at the design target value. This integrates complex precipitation design calculations and automated control into a complete hardware device, realizing full-process automation from parameter input to wellpoint deployment and process control. Engineers no longer need to perform tedious manual calculations and adjustments; they only need to input basic parameters, and the device can autonomously complete the wellpoint spacing design and precipitation process control, significantly reducing the technical threshold and labor costs of precipitation engineering, and improving construction efficiency and control accuracy.

[0117] This application also provides a foundation pit engineering dewatering control system, including the foundation pit engineering dewatering control device as described above.

[0118] In this embodiment, the system is built around a dewatering control device for foundation pit engineering. Specifically, the system includes at least one of the aforementioned control devices, which integrates an acquisition unit, a computing unit, a deployment unit, and a control unit. Integrating isolated dewatering control devices into a unified scheduling system enables global monitoring and collaborative management of large-scale foundation pit dewatering projects. The central monitoring platform allows managers to grasp the operational status of the entire dewatering site in real time, promptly detect and handle anomalies, and prevent local problems from escalating. Cloud services break geographical limitations, enabling experts to conduct remote consultations and provide construction guidance. This system significantly improves the automation and informatization level of dewatering management, and is particularly suitable for complex engineering scenarios involving ultra-large-scale foundation pits or multiple interconnected foundation pits.

[0119] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0120] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for controlling dewatering in foundation pit engineering, characterized in that, The method includes: Obtain the soil layer parameters of the foundation pit, wherein the soil layer parameters include at least: soil permeability coefficient. Aquifer thickness Radius of influence Well point radius Coefficient of soil uniformity Groundwater seepage rate and initial groundwater level ; According to the design drawdown Design precipitation time and safety factor The mathematical model for constructing the optimal well point spacing L is as follows: ; in, This indicates the optimal wellpoint spacing, in meters. This represents the soil permeability coefficient, expressed in m / d. This indicates the thickness of the aquifer, in meters (m). This indicates the design precipitation time, expressed in days (d). This indicates the design drawdown, in meters (m). The safety factor is dimensionless. Indicates the radius of influence, in meters (m). This represents the well point radius, in meters (m). This represents the soil unevenness coefficient, which is dimensionless. This indicates the groundwater seepage velocity, expressed in m / d. Represents the natural constant; Multiple independently controllable tubular well points are deployed according to the optimal well point spacing L; each of the tubular well points is equipped with a variable frequency submersible pump; The operating status of the variable frequency submersible pump equipped at each of the aforementioned well points is controlled, thereby adjusting the current dewatering intensity Q(t) of the foundation pit project so that the water level of the foundation pit project reaches the design dewatering level. .

2. The method for controlling dewatering in foundation pit engineering according to claim 1, characterized in that, The adjustment of the current precipitation intensity Q(t) of the foundation pit project includes: The mathematical model for the current precipitation intensity Q(t) is as follows: ; in, This indicates the initial precipitation intensity, expressed in m³ / h. This represents the precipitation regulation coefficient, which is dimensionless. This represents the measured groundwater level at time t, in meters (m). This indicates the design precipitation level, in meters (m). This indicates the initial groundwater level, in meters (m). The value represents the precipitation attenuation factor, which is dimensionless; t represents the time since precipitation occurred, in hours. This represents the total designed precipitation time, in hours, and T = 24. .

3. The method for controlling dewatering in foundation pit engineering according to claim 2, characterized in that, The initial precipitation intensity The calculation methods include: The initial precipitation intensity is constructed based on the minimum horizontal width B of the foundation pit. The mathematical model is as follows: ; Where B represents the minimum horizontal width of the foundation pit, in meters; for rectangular foundation pits, B is the length of the shorter side; for irregular foundation pits, B is the minimum horizontal distance between any two points.

4. The method for controlling dewatering in foundation pit engineering according to claim 1, characterized in that, The mathematical model for constructing the optimal well point spacing L also includes: The mathematical model for constructing the safety factor S is as follows: ; Where S represents the safety factor, which is dimensionless; This represents the hyperbolic tangent function.

5. The method for controlling dewatering in foundation pit engineering according to claim 2, characterized in that, The precipitation regulation coefficient The calculation method is as follows: ; Where k represents the soil permeability coefficient.

6. The method for controlling dewatering in foundation pit engineering according to claim 1, characterized in that, The arrangement of multiple independently controllable well points according to the optimal well point spacing L includes: When laying out the well points, the well points are arranged in a quincunx or rectangular pattern, and the spacing between well points at the corners of the foundation pit is set to 0.6 to 0.8 times the optimal spacing L of the well points.

7. The method for controlling dewatering in foundation pit engineering according to claim 1, characterized in that, Adjusting the current precipitation intensity Q(t) of the foundation pit project to ensure that the water level of the foundation pit project reaches the design precipitation level includes: When the calculated Q(t) exceeds 1.2 times the rated flow of the water pump or is less than 0.3 times the rated flow of the water pump, an early warning signal is generated and the precipitation intensity of the previous moment is maintained.

8. The method for controlling dewatering in foundation pit engineering according to claim 1, characterized in that, The precipitation attenuation factor γ ranges from 0.95 to 0.99 and is determined based on the ratio of the precipitation influence radius to the pit size; the larger the ratio, the larger the value of γ.

9. A dewatering control device for foundation pit engineering, characterized in that, The foundation pit engineering dewatering control device includes: Acquisition Unit: Used to acquire soil parameters of the foundation pit, wherein the soil parameters include at least: soil permeability coefficient. Aquifer thickness Radius of influence Well point radius Coefficient of soil uniformity Groundwater seepage rate and initial groundwater level ; Calculation unit: used to calculate the design drawdown. Design precipitation time and safety factor The mathematical model for constructing the optimal well point spacing L is as follows: ; in, This indicates the optimal wellpoint spacing, in meters. This represents the soil permeability coefficient, expressed in m / d. This indicates the thickness of the aquifer, in meters (m). This indicates the design precipitation time, expressed in days (d). This indicates the design drawdown, in meters (m). The safety factor is dimensionless. Indicates the radius of influence, in meters (m). This represents the well point radius, in meters (m). This represents the soil unevenness coefficient, which is dimensionless. This indicates the groundwater seepage velocity, expressed in m / d. Represents the natural constant; Deployment unit: used to deploy multiple independently controllable tubular well points according to the optimal spacing L of the well points; wherein each of the tubular well points is equipped with a variable frequency submersible pump; Control unit: Used to control the operating status of the variable frequency submersible pump equipped at each of the well points, thereby adjusting the current dewatering intensity Q(t) of the foundation pit project so that the water level of the foundation pit project reaches the design dewatering level. .

10. A dewatering control system for foundation pit engineering, characterized in that, Includes the dewatering control device for foundation pit engineering as described in claim 9.

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