Method and device for controlling underground water of confined water foundation pit and electronic equipment

Abstract

The invention discloses a confined water foundation pit underground water control method and device and electronic equipment, and relates to the field of foundation pit engineering safety or other related technical fields, and the method comprises the steps: analyzing the distribution characteristics of a rock-soil layer and the type of underground water, and measuring and calculating the confined water pressure of a foundation pit; based on the pressure of the confined water, checking calculation analysis is conducted on the bottom of the pit collapsed by the confined water, the overburden layer elevation is obtained, and the overburden layer elevation is used for determining the excavation limiting elevation where measures need to be taken to prevent piping; carrying out seepage stability analysis on the basis of the elevation of the overburden layer, determining the position and the bottom elevation of a water cut-off curtain, and generating a water cut-off curtain scheme; a finite element software model is adopted to calculate the seepage flow of the foundation pit, a pressure relief well is arranged according to the calculation result of the seepage flow of the foundation pit and the conditions of the foundation pit, and the pressure relief well is utilized to discharge and flatten confined water. The technical problem that in the prior art, when underground water control cannot be conducted in foundation pit engineering, pressure relief well design is conducted in a trial-and-error mode, and efficiency is low is solved.

Description

Technical Field

[0001] This invention relates to the field of foundation pit engineering safety technology or other related fields. Specifically, it relates to a method and device for controlling groundwater in confined water foundation pits, as well as electronic equipment. Background Technology

[0002] In urban infrastructure construction, foundation pit engineering is an indispensable part, especially when basements, underground parking garages, underground stations, or underground pipeline construction are required. Among these, groundwater control in foundation pit engineering is an extremely challenging task, as it directly affects the safety and stability of the foundation pit and the safety of the surrounding environment. Improper groundwater control can not only lead to water inrush, piping, and soil erosion during foundation pit excavation, but also cause settlement of surrounding buildings, underground pipelines, and structures, thus seriously threatening the safety of construction workers and the overall quality of the project.

[0003] In related technologies, methods for controlling groundwater in foundation pits, such as those mentioned in the "Technical Specification for Foundation Pit Support," stipulate that when a confined aquifer exists at the bottom of the foundation pit, and the pressure of the confined water is sufficient to threaten the safety of the pit, measures should be taken to lower the confined water level to prevent the confined water from eroding the bottom or slope of the pit. However, in groundwater control, related technologies often rely on the experience of engineers, using trial and error to select the curtain wall and design the depressurization well. This limits the accuracy and efficiency of the design to some extent, and when the excavation depth of the foundation pit is large or the groundwater permeability is high, it is impossible to provide a reasonable foundation pit engineering design scheme.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This invention provides a method, apparatus, and electronic device for controlling groundwater in confined water foundation pits, which at least solves the technical problem of low efficiency in designing depressurization wells through trial and error when groundwater control is not possible in foundation pit engineering.

[0006] According to one aspect of the present invention, a method for controlling groundwater in a confined aquifer foundation pit is provided, comprising: analyzing the distribution characteristics of soil and rock layers and the type of groundwater, and calculating the confined water pressure of the foundation pit; based on the confined water pressure, performing a verification analysis on the confined water breaching the bottom of the pit to obtain the elevation of the overlying soil layer, wherein the elevation of the overlying soil layer is used to determine the excavation limit elevation for which measures need to be taken to prevent piping; based on the elevation of the overlying soil layer, performing a seepage stability analysis to determine the location and bottom elevation of the cutoff wall, and generating a cutoff wall scheme; calculating the seepage flow rate of the foundation pit using a finite element software model, arranging pressure relief wells according to the calculation results of the seepage flow rate and the conditions of the foundation pit, and using the pressure relief wells to discharge and stabilize the confined water.

[0007] Optionally, the steps of analyzing the distribution characteristics of soil and rock layers and the type of groundwater to calculate the confined water pressure of the foundation pit include: determining the groundwater elevation in the confined aquifer through borehole tests; and calculating the confined water pressure of the foundation pit based on the groundwater density, gravitational acceleration value, and confined water head height.

[0008] Optionally, the step of performing a verification analysis of the confined water erosion of the pit bottom based on the confined water pressure to obtain the elevation of the overlying soil layer includes: calculating the excavation depth based on the groundwater elevation and the bottom elevation of the excavation pit; determining the unit weight value of groundwater and the hydraulic head value of confined water based on the geological survey report, and determining the pressure value of confined water by combining the unit weight value of groundwater and the hydraulic head value of confined water; determining the unit weight value of soil based on the geological survey report, and calculating the self-weight pressure value of the soil within the range from the bottom of the pit to the upper interface of the confined water layer by combining the soil unit weight value, the pressure value of the confined water, and a preset safety factor; and calculating the elevation of the overlying soil layer based on the self-weight pressure value of the soil within the range from the bottom of the pit to the upper interface of the confined water layer and the excavation depth.

[0009] Optionally, the steps of performing seepage stability analysis based on the elevation of the overlying soil layer to determine the location and bottom elevation of the cutoff curtain and generate a cutoff curtain scheme include: calculating the bottom elevation of the cutoff curtain based on the groundwater elevation in the confined aquifer, the buoyancy of the soil, and the unit weight of the groundwater; determining the final bottom elevation of the cutoff curtain based on the bottom elevation of the cutoff curtain and the safety range for preventing sudden inrush; and calculating the location of the cutoff curtain based on the elevation of the overlying soil layer and the final bottom elevation of the cutoff curtain.

[0010] Optionally, the step of performing seepage stability analysis based on the elevation of the overlying soil layer to determine the location and bottom elevation of the cutoff curtain and generate a cutoff curtain scheme further includes: determining a continuous cement wall cutoff curtain scheme, a high-pressure jet grouting pile cutoff curtain scheme, a diaphragm wall cutoff curtain scheme, a construction method pile cutoff curtain scheme, and a sheet pile cutoff curtain scheme based on the final bottom elevation and location of the cutoff curtain; scoring each cutoff curtain scheme from the perspectives of safety, construction efficiency, environmental impact, and scenario-based selection; and selecting the cutoff curtain scheme with the highest comprehensive score as the final cutoff curtain scheme.

[0011] Optionally, the step of calculating the seepage flow of the foundation pit using a finite element software model includes: defining the model size of the finite element software model based on the curtain depth at the location of the cutoff curtain; obtaining the soil unit weight, groundwater unit weight, and water level data at various locations for each soil layer based on the geological survey report; inputting the soil unit weight, groundwater unit weight, water level data at various locations, and initial groundwater level data for each soil layer into the finite element software model; dividing the finite element software model into a mesh using a mesh density; and calculating the seepage flow of the foundation pit using the meshed finite element software model to obtain the distribution lines of different water levels and the seepage flow for different permeability coefficients of the silty sand layer.

[0012] Optionally, the step of arranging pressure relief wells according to the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and using the pressure relief wells to discharge and depressurize the confined water, includes: selecting a pressure relief well scheme to be arranged according to the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and setting up a water pump to pump water to the target location of the foundation pit.

[0013] Optionally, after arranging pressure relief wells based on the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and using the pressure relief wells to discharge and stabilize the confined water, the method further includes: obtaining the depth from the ground surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well; calculating the total depth of the recharge wells based on the depth from the ground surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well; calculating the recharge influence radius of a single well, and determining the recharge well spacing by combining the recharge influence radius of a single well, the pre-set overlap range of the influence range of adjacent wells, and the arrangement density of the dewatering wells; obtaining the total dewatering pumping volume of the foundation pit, and determining the total recharge volume based on the total dewatering pumping volume of the foundation pit; determining the recharge volume of a single well based on the total recharge volume and the allowable recharge intensity of the aquifer; and setting up recharge wells around the dewatering area based on the total depth of the recharge wells, the recharge well spacing, and the recharge volume of a single well, and using the recharge wells to inject clean water into the ground to form a water level barrier to offset the surrounding soil settlement caused by dewatering.

[0014] Optionally, after arranging pressure relief wells based on the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and using the pressure relief wells to discharge and depressurize the confined water, the method further includes: setting up a water interception barrier outside the excavation range of the foundation pit to intercept surface runoff around the site; setting up a drainage channel inside the foundation pit to guide groundwater seeping from the slope of the foundation pit and water accumulating at the bottom of the pit to a centralized collection point, wherein the drainage channel includes at least one of the following: an internal interception ditch and a drainage ditch; the centralized collection point includes: a collection well; and installing pumping and drainage equipment in the centralized collection point to continuously pump the collected water to the drainage system outside the foundation pit.

[0015] Optionally, after arranging pressure relief wells based on the calculated seepage flow rate and conditions of the foundation pit, and using the pressure relief wells to discharge and stabilize the confined water, the method further includes: setting monitoring points at easily deformable parts of the foundation pit slope, wherein the easily deformable parts include at least one of the following: the top of the foundation pit slope, the building foundation, and the toe of the foundation pit slope; using the monitoring points to monitor the excavation process of the foundation pit, and determining whether a groundwater inrush hazard occurs based on the monitoring results; and setting a water level gauge at the centralized collection point of the foundation pit to observe water level changes.

[0016] According to another aspect of the present invention, a groundwater control device for a confined aquifer foundation pit is also provided, comprising: a confined aquifer pressure calculation unit, used to analyze the distribution characteristics of soil and rock layers and groundwater type, and calculate the confined aquifer pressure of the foundation pit; an overlying soil elevation calculation unit, used to perform a verification analysis of the confined aquifer erosion of the pit bottom based on the confined aquifer pressure, and obtain the overlying soil elevation, wherein the overlying soil elevation is used to determine the excavation limit elevation for which measures need to be taken to prevent piping; a cutoff wall scheme determination unit, used to perform seepage stability analysis based on the overlying soil elevation, determine the cutoff wall location and bottom elevation, and generate a cutoff wall scheme; and a confined aquifer depressurization unit, used to calculate the seepage flow of the foundation pit using a finite element software model, arrange depressurization wells according to the calculation results of the seepage flow and the foundation pit conditions, and use the depressurization wells to discharge and depressurize the confined aquifer.

[0017] According to another aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to perform the groundwater control method for any of the above-mentioned confined water foundation pits.

[0018] According to another aspect of the present invention, an electronic device is also provided, including one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the groundwater control method for confined water foundation pits described above.

[0019] According to another aspect of the present invention, a computer program product is also provided, including a computer program that, when executed by a processor, implements the steps of the groundwater control method for confined water foundation pits described in any of the above embodiments.

[0020] In this disclosure, the distribution characteristics of soil and rock layers and the type of groundwater are analyzed, and the confined water pressure of the foundation pit is calculated. Based on the confined water pressure, a verification analysis of the confined water breaching the bottom of the pit is conducted to obtain the elevation of the overlying soil layer. The elevation of the overlying soil layer is used to determine the excavation limit elevation for which measures need to be taken to prevent piping. Based on the elevation of the overlying soil layer, a seepage stability analysis is conducted to determine the location and bottom elevation of the cutoff wall and generate a cutoff wall scheme. The seepage flow of the foundation pit is calculated using a finite element software model. Based on the calculation results of the seepage flow of the foundation pit and the conditions of the foundation pit, pressure relief wells are arranged, and the pressure relief wells are used to discharge and stabilize the confined water.

[0021] In this disclosure, the calculation and analysis of the confined water erosion of the pit bottom can be performed based on the confined water pressure to obtain the elevation of the overlying soil layer. Then, the optimal location and depth of the cutoff wall can be determined to ensure the safety and stability of the foundation pit in the confined water environment, effectively prevent the bottom of the pit from gushing and the slope from becoming unstable. By selecting the most suitable cutoff wall scheme and wall type, the waste of resources caused by over-design can be avoided. Finally, seepage analysis is performed using finite element software to accurately calculate the seepage flow in the foundation pit, guide the design of the pressure relief well, ensure the dewatering effect and prevent abnormal drop in the water level outside the pit, improve the efficiency of pressure relief well layout, and improve the accuracy of groundwater control in foundation pit engineering. This solves the technical problem of low efficiency in the design of pressure relief wells by trial and error when groundwater control is not possible in foundation pit engineering. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0023] Figure 1 This is a flowchart of an optional groundwater control method for confined aquifer foundation pit according to an embodiment of the present invention;

[0024] Figure 2 This is a cross-sectional view of the foundation pit excavation according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the anti-surge stability verification according to an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the soil stability calculation when using a suspended curtain for water interception according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the bottom elevation of a water-cutting curtain according to an embodiment of the present invention.

[0028] Figure 6 This is a layout diagram of an optional water-cutting curtain scheme according to an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of an optional setting of a dewatering well according to an embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of an optional groundwater control device for a confined water foundation pit according to an embodiment of the present invention;

[0031] Figure 9 This is a hardware structure block diagram of an electronic device (or mobile device) for implementing a groundwater control method for a confined water foundation pit according to an embodiment of the present invention. Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0033] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] To facilitate understanding of the present invention by those skilled in the art, some terms or nouns involved in the various embodiments of the present invention are explained below:

[0035] TRD Continuous Cement Wall Curtain Solution is a continuous wall construction method that uses a chainsaw-type cutting machine to mix cement slurry with soil to form a continuous, seamless cement-soil wall for water stopping and reinforcing soft soil layers.

[0036] The construction method pile water-cutting curtain scheme, Soil Mixing Wall with Steel Sheet Pile, is a composite support structure combining deep mixing piles and steel sheet piles. The mixing piles serve to stop water flow, while the steel sheet piles provide additional support. It is suitable for soft soil areas.

[0037] Diaphragm walls are formed by continuously trenching on the ground surface and then pouring concrete to create a continuous wall structure. They are suitable for groundwater control and support structures in deep foundation pits and high water table areas.

[0038] The Finite Element Method (FEM) is a mathematical tool used for modeling physical systems in engineering analysis, such as structural mechanics and fluid mechanics. It can calculate seepage and stress distribution during the excavation of foundation pits.

[0039] It should be noted that the groundwater control method and device for confined water foundation pits disclosed herein can be used in the field of foundation pit engineering safety technology to achieve groundwater control in confined water foundation pits, and can also be used in any field other than the field of foundation pit engineering safety technology to achieve groundwater control in confined water foundation pits. This disclosure does not limit the application field of the groundwater control method and device for confined water foundation pits.

[0040] It should be noted that in this disclosure, customer information is collected and analyzed, and users are provided with corresponding operation entry points to choose whether to agree to or reject the automated decision results; if the user chooses to reject, the process will proceed to the expert decision-making process.

[0041] The following embodiments of the present invention can be applied to various systems / applications / equipment for groundwater control in confined aquifer foundation pits. The present invention is applicable to various scenarios such as building construction and water conservancy projects, including applications in foundation pit excavation and groundwater control in urban infrastructure construction, underground transportation networks (such as subways and tunnels), and bridge and culvert projects. Specifically, the groundwater control method, device, and electronic equipment for confined aquifer foundation pits provided by this invention can be applied to any engineering project involving the excavation of foundation pits above confined aquifers, requiring control of groundwater levels, prevention of water inrush, piping, and soil erosion, and minimization of impacts on surrounding buildings and the environment.

[0042] Water inrush, piping, and soil erosion are common modes of failure in foundation pit engineering. The safety of foundation pit engineering directly affects the project's progress and quality, making foundation pit safety extremely important. Groundwater control is a key technology for preventing water inrush, piping, soil erosion, and settlement of the surrounding environment during foundation pit excavation. The core objective is to control the groundwater level through "water stoppage," "water dewatering," or a combination of both.

[0043] This invention significantly improves the accuracy and economy of groundwater control in foundation pit engineering. It uses quantitative methods to determine the optimal location and depth of the cutoff wall, ensuring the safety and stability of the foundation pit in a confined water environment and effectively preventing bottom heave and slope instability. Furthermore, by comparing the technical and economic aspects of different cutoff wall schemes, the most suitable type of cutoff wall is selected, avoiding resource waste caused by over-design and achieving cost control.

[0044] Finite element analysis software was used to accurately calculate the seepage flow within the foundation pit, guiding the design of pressure relief wells to ensure effective dewatering and prevent abnormal drops in water levels outside the pit. By rationally arranging pressure relief wells and recharge wells, the water level difference between the inside and outside of the pit was balanced, reducing the impact on surrounding buildings and surface settlement. Simultaneously, an intercepting and drainage system effectively controlled surface runoff and shallow groundwater, minimizing water waste.

[0045] The present invention will now be described in detail with reference to various embodiments.

[0046] Example 1

[0047] According to an embodiment of the present invention, an embodiment of a method for controlling groundwater in a confined water foundation pit is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0048] Figure 1 This is a flowchart of an optional groundwater control method for confined aquifer foundation pit according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps S101 to S104. The present invention will be described in detail below with reference to each implementation step.

[0049] Step S101: Analyze the distribution characteristics of the soil and rock layers and the type of groundwater, and calculate the confined water pressure of the foundation pit.

[0050] This embodiment utilizes geological survey reports to understand the stratigraphic structure, including the type of each soil layer (such as silty clay, silt, and sand), its distribution elevation (i.e., burial depth), and the physical and mechanical properties of each layer. This helps identify which soil layers are the main aquifers of confined water and their distribution. In addition to geotechnical analysis, this embodiment also involves identifying the state of groundwater, distinguishing between unconfined and confined water. The presence of confined water means that the groundwater level is affected by closed aquifers within the strata, and its pressure may pose unique challenges to foundation pit excavation.

[0051] Optionally, the steps of analyzing the distribution characteristics of soil and rock layers and the type of groundwater to calculate the confined water pressure of the foundation pit include: determining the groundwater elevation in the confined aquifer through borehole tests; and calculating the confined water pressure of the foundation pit based on the groundwater density, gravitational acceleration value, and confined water head height.

[0052] Through borehole testing, this embodiment can directly obtain the actual water level data in the confined aquifer. That is, by drilling, the confined aquifer can be exposed, and water level or pressure data can be directly obtained. The core is to utilize the "conversion relationship between confined water level (piezometric level) and pressure" (formula: p=ρgh, where p is the confined water pressure, ρ is the groundwater density, g is the gravitational acceleration, and h is the "height difference between the piezometric level and the top of the aquifer", i.e., the confined water head height).

[0053] Step S102: Based on the pressure of the confined water, perform a verification analysis on the confined water breaching the bottom of the pit to obtain the elevation of the overlying soil layer. The elevation of the overlying soil layer is used to determine the excavation limit elevation for which measures need to be taken to prevent piping.

[0054] Optionally, the step of performing a verification analysis of the confined water erosion of the pit bottom based on the confined water pressure to obtain the elevation of the overlying soil layer includes: calculating the excavation depth based on the groundwater elevation and the bottom elevation of the excavation pit; determining the unit weight value of groundwater and the hydraulic head value of confined water based on the geological survey report, and determining the pressure value of confined water by combining the unit weight value of groundwater and the hydraulic head value of confined water; determining the unit weight value of soil based on the geological survey report, and calculating the self-weight pressure value of the soil within the range from the bottom of the pit to the upper interface of the confined water layer by combining the soil unit weight value, the pressure value of confined water, and a preset safety factor; and calculating the elevation of the overlying soil layer based on the self-weight pressure value of the soil within the range from the bottom of the pit to the upper interface of the confined water layer and the excavation depth.

[0055] Based on the groundwater elevation extracted from the geological survey report and the planned excavation bottom elevation, this embodiment calculates the excavation depth. Then, based on the groundwater unit weight value and the confined water head provided in the geological survey report, this embodiment uses physical formulas to calculate the confined water pressure value. Next, this embodiment refers to the soil unit weight value in the geological survey report, combines it with the previously calculated confined water pressure value, and considers a preset safety factor to calculate the soil self-weight pressure within the range from the bottom of the excavation pit to the upper interface of the overlying confined water layer. This helps to understand the stability of the excavation pit in a confined water environment and is an important basis for determining what piping prevention measures to take. Finally, based on the previously calculated self-weight pressure value and excavation depth, this embodiment calculates the elevation of the overlying soil layer. This elevation serves as a limiting point for excavation operations, helping to identify the piping protection measures required at a specific depth, ensuring the smooth progress of the excavation pit, and avoiding the risk of sudden water inrush caused by confined water pressure.

[0056] Step S103: Based on the elevation of the overlying soil layer, perform seepage stability analysis to determine the location and bottom elevation of the cutoff curtain and generate a cutoff curtain scheme.

[0057] Optionally, the steps of performing seepage stability analysis based on the elevation of the overlying soil layer to determine the location and bottom elevation of the cutoff curtain and generate the cutoff curtain scheme include: calculating the bottom elevation of the cutoff curtain based on the groundwater elevation in the confined aquifer, the buoyancy unit weight of the soil, and the unit weight value of the groundwater; determining the final bottom elevation of the cutoff curtain based on the bottom elevation of the cutoff curtain and the safety range for preventing sudden surges; and calculating the location of the cutoff curtain based on the elevation of the overlying soil layer and the final bottom elevation of the cutoff curtain.

[0058] Using the actual elevation of groundwater in the confined aquifer, combined with the buoyant unit weight of the soil and the unit weight of the groundwater, this embodiment employs a mathematical model to calculate the bottom elevation. Specifically, a comparative analysis of the confined water pressure and the soil's self-weight pressure can be used to determine the minimum elevation at which the cutoff wall can withstand the impact of confined water. Based on the preliminary calculation of the cutoff wall's bottom elevation, this embodiment further considers the safety range for preventing sudden surges, ensuring that even in extreme conditions, the cutoff wall maintains sufficient stability, thus improving the robustness of the scheme and preventing piping caused by a sudden increase in confined water pressure.

[0059] After determining the bottom elevation and location of the cutoff wall, this embodiment can generate various specific cutoff wall schemes, each detailing the type, size, material selection, and construction details of the cutoff wall. Optionally, the step of performing seepage stability analysis based on the overlying soil elevation to determine the cutoff wall location and bottom elevation, and generating the cutoff wall scheme, further includes: determining the continuous cement wall cutoff wall scheme, high-pressure jet grouting pile cutoff wall scheme, underground continuous wall cutoff wall scheme, construction method pile cutoff wall scheme, and steel sheet pile cutoff wall scheme based on the final cutoff wall bottom elevation and location; scoring each cutoff wall scheme from the perspectives of safety, construction efficiency, environmental impact, and scenario-based selection; and selecting the cutoff wall scheme with the highest comprehensive score as the final cutoff wall scheme.

[0060] This embodiment generates a series of cutoff wall schemes, including but not limited to continuous cement wall cutoff wall, high-pressure jet grouting pile cutoff wall, underground continuous wall cutoff wall, construction method pile cutoff wall, and steel sheet pile cutoff wall schemes. Based on the final determined bottom elevation and location of the cutoff wall, this embodiment generates five cutoff wall schemes, each designed to meet specific engineering requirements and environmental conditions. After the schemes are generated, this embodiment comprehensively evaluates each scheme from four dimensions—safety, construction efficiency, environmental impact, and scenario-based selection. The evaluation mechanism considers project characteristics, construction conditions, and sensitivity to the surrounding environment, aiming to find a balance point that maximizes construction efficiency and minimizes environmental burden while ensuring the safety of the foundation pit.

[0061] This embodiment comprehensively considers various scores and selects the cutoff wall scheme with the highest overall score as the final implementation plan for this project. The selection process fully incorporates the advantages of each scheme, striving to achieve the best groundwater control effect under the complex engineering background.

[0062] Step S104: Calculate the seepage flow of the foundation pit using a finite element software model. Based on the calculation results of the seepage flow and the conditions of the foundation pit, arrange pressure relief wells and use the pressure relief wells to discharge confined water and level the pressure.

[0063] Optionally, the steps for calculating the seepage flow of the foundation pit using a finite element software model include: defining the model dimensions of the finite element software model based on the depth of the cutoff wall location; obtaining the soil unit weight, groundwater unit weight, and water level data for each soil layer based on the geological survey report; inputting the soil unit weight, groundwater unit weight, water level data for each soil layer, and initial groundwater level data into the finite element software model; meshing the finite element software model using a mesh density; and calculating the seepage flow of the foundation pit using the meshed finite element software model to obtain the distribution lines of different water levels and the seepage flow for different permeability coefficients of the silty sand layer.

[0064] First, in this embodiment, the model size of the finite element software model is defined based on the curtain depth determined by the location of the cutoff curtain. For example, by setting the model size to 100 times the curtain depth, i.e., by using the calculated value (e.g., 31-9.35=20.65m, which can be appropriately expanded to 3000m×3000m), the model can be ensured to fully reflect the groundwater flow around the foundation pit, thereby improving the accuracy of seepage analysis.

[0065] Based on the geological survey report, this embodiment accurately obtains data on the unit weight of soil layers, the unit weight of groundwater, and the water level at various locations for each soil layer. These data, along with the initial groundwater level data, are input into the finite element software model. An appropriate mesh density is used to divide the model into meshes, and then the seepage flow of the foundation pit is calculated using the meshed finite element software model. The calculation process not only yields the seepage distribution lines of the foundation pit at different water levels but also accurately calculates the seepage flow when the permeability coefficient of the silty sand layer changes.

[0066] Optionally, the steps of arranging pressure relief wells according to the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and using the pressure relief wells to discharge and depressurize the confined water, include: selecting the pressure relief well scheme to be arranged according to the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and setting up a water pump to pump water to the target location of the foundation pit.

[0067] Based on the analysis of seepage flow and conditions in the foundation pit, this embodiment selects the most suitable depressurization well scheme (such as lightweight wellpoint, jet wellpoint, tubular wellpoint, electro-osmotic wellpoint, or vacuum deep well dewatering). Each scheme has its unique applicable scope and performance advantages, and factors such as foundation pit depth, soil properties, seepage rate, construction cost, and efficiency must be considered when selecting one.

[0068] After determining the pressure relief well scheme, this embodiment further includes the installation of pumps to facilitate effective dewatering at the target location of the foundation pit. The selection of pumps is based on the required pumping volume and head, ensuring timely removal of confined water from the foundation pit while maintaining the water level within a safe and controllable range. Based on the seepage flow calculation results and foundation pit conditions, this embodiment optimizes the layout of the pressure relief wells, including the number, depth, location, and relationship with surrounding facilities. This helps ensure a balanced distribution of pressure relief wells, effectively reducing the impact of confined water on the foundation pit while avoiding unnecessary disturbance to the surrounding environment.

[0069] By starting and adjusting the pumps, this embodiment begins the pumping operation of the pressure relief well. The purpose is to lower the water level in the foundation pit to a predetermined level, thereby reducing the pressure of the confined water and achieving a balance of water pressure inside and outside the foundation pit. During the pumping operation, this embodiment can monitor changes in the foundation pit water level in real time and adjust the pumping rate or the operating status of the pumps as necessary. Dynamic monitoring and adjustment help maintain the stability of the foundation pit water level and avoid affecting the project progress or construction safety due to abnormal water level fluctuations.

[0070] Through the above steps, the distribution characteristics of the soil and rock layers and the type of groundwater can be analyzed, and the confined water pressure of the foundation pit can be calculated. Based on the confined water pressure, the verification analysis of the confined water breaching the bottom of the pit is carried out to obtain the elevation of the overlying soil layer. The elevation of the overlying soil layer is used to determine the excavation limit elevation for which measures need to be taken to prevent piping. Based on the elevation of the overlying soil layer, seepage stability analysis is carried out to determine the location and bottom elevation of the cutoff wall and generate a cutoff wall scheme. The seepage flow of the foundation pit is calculated using a finite element software model. According to the calculation results of the seepage flow of the foundation pit and the foundation pit conditions, pressure relief wells are arranged and used to discharge and stabilize the confined water. In this embodiment, the pressure of confined water can be used to perform a verification analysis of the confined water breach at the bottom of the pit, thereby obtaining the elevation of the overlying soil layer. Then, the optimal location and depth of the cutoff wall can be determined to ensure the safety and stability of the foundation pit in a confined water environment, effectively preventing bottom heave and slope instability. By selecting the most suitable cutoff wall scheme and type, resource waste caused by over-design can be avoided. Finally, finite element software is used to perform seepage analysis to accurately calculate the seepage flow in the foundation pit, guiding the design of the depressurization wells, ensuring the dewatering effect and preventing abnormal drop in the water level outside the pit, improving the efficiency of depressurization well layout, and improving the accuracy of groundwater control in foundation pit engineering. This solves the technical problem of low efficiency in designing depressurization wells through trial and error when groundwater control is not possible in foundation pit engineering.

[0071] Optionally, after arranging pressure relief wells based on the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and using the pressure relief wells to discharge and stabilize the confined water, the process further includes: obtaining the depth from the ground surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well; calculating the total depth of the recharge wells based on the depth from the ground surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well; calculating the recharge influence radius of a single well, and determining the recharge well spacing by combining the recharge influence radius of a single well, the pre-set overlap range of the influence range of adjacent wells, and the layout density of the dewatering wells; obtaining the total dewatering pumping volume of the foundation pit, and determining the total recharge volume based on the total dewatering pumping volume of the foundation pit; determining the recharge volume of a single well based on the total recharge volume and the allowable recharge intensity of the aquifer; and setting up recharge wells around the dewatering area based on the total depth of the recharge wells, the recharge well spacing, and the recharge volume of a single well, and using the recharge wells to inject clean water into the ground to form a water level barrier to offset the surrounding soil settlement caused by the dewatering.

[0072] Recharge technology involves setting up recharge wells around the precipitation area to inject clean water into the ground, forming a "water level barrier" to counteract the soil settlement caused by precipitation. It is commonly used in sensitive areas such as adjacent buildings and subway tunnels. When determining the depth of the recharge wells, it is necessary to ensure that the recharge water can directly enter the target aquifer pumped by the precipitation well, while avoiding damage to the impermeable layer or affecting the foundation stability of surrounding buildings. Specifically, three key factors need to be considered: 1. Matching the depth with the depth of the precipitation well filter pipe; 2. Avoiding the sensitive depths of surrounding protected objects; 3. Combining the aquifer thickness with the distribution of the impermeable layer.

[0073] Regarding the first key factor, the essence of recharge is to "replenish the water volume in the precipitation funnel area." Therefore, the filter pipe section of the recharge well must be located in the same aquifer (unconfined or confined aquifer) as the filter pipe section of the precipitation well, and the length of the filter pipe should be close to or slightly longer than that of the precipitation well filter pipe to ensure that the recharge water can directly fill the pumped water body. For example, if the precipitation well is an "unconfined well" (pumping out unconfined water), and the filter pipe section is located 5-15m below the surface (corresponding to the unconfined aquifer), then the filter pipe of the recharge well should also be set within the range of 5-15m, and the bottom should not penetrate the underlying impermeable layer (to avoid water seeping into the deep ineffective area); if the precipitation well is a "confined aquifer" (pumping out confined water), the filter pipe of the recharge well needs to be precisely aligned with the confined aquifer, and the top needs to penetrate 1-m below the top plate of the confined aquifer to prevent the recharge water from leaking into the unconfined aquifer.

[0074] Regarding the second key factor, if there are buildings or underground pipelines nearby, the depth of the recharge well should avoid the foundation bearing layer or the burial depth of the pipelines to prevent the recharge pressure from causing ground uplift or foundation disturbance. For example, if the foundation of the surrounding buildings is buried at a depth of 8m (the bearing layer is a silty clay layer 8-12m below the surface), then the filter pipe of the recharge well should avoid the 8-12m range. If the target aquifer overlaps with the bearing layer, the recharge pressure should be reduced and the length of the filter pipe in the bearing layer should be shortened.

[0075] Regarding the third key factor, if the aquifer thickness is small (e.g., <5m), the filter pipe of the reinjection well should cover the entire aquifer thickness to ensure the maximum recharge area; if the aquifer has multiple interlayers (e.g., sand mixed with clay), the filter pipe should only be installed in the sandy layer section with good permeability to avoid the clay section clogging the filter pipe (preventing reinjection water from seeping in).

[0076] The total depth of the reinjection well = depth from the surface to the top of the filter pipe + length of the filter pipe + length of the sedimentation section from the bottom of the filter pipe to the bottom of the well (which can be selected as 0.5-1m to prevent silt from entering the filter pipe); the key is that the filter pipe section and the dewatering well filter pipe section are "in the same layer and within the same range".

[0077] In addition, regarding the spacing between injection wells, it is necessary to ensure that the precipitation funnel is fully covered, and the spacing between recharge wells must ensure that the "recharge influence range" of adjacent recharge wells overlaps to form a continuous "water level protection zone" to avoid local subsidence caused by the lack of recharge in the precipitation funnel. The specific determination method is divided into three steps: First, calculate the recharge influence radius (R) of a single well; the recharge influence radius is the maximum range that a single recharge well can effectively recharge, which is directly related to the aquifer permeability coefficient (k), recharge pressure, and aquifer thickness (M), and needs to be calculated through "field recharge test" or empirical formula: Field test method (most accurate): Drill 1-2 test recharge wells, recharge at the design pressure, monitor the groundwater level changes at different distances around, and the distance at which the water level no longer rises significantly is the actual influence radius R. The second step is to determine the spacing based on the overlap of the affected areas. To ensure there are no blind spots in the recharge, the spacing (L) between recharge wells must meet the following condition: L≤1.5-2.0×R (i.e., the affected areas of adjacent wells overlap by 30%-50%). For example, if the test shows R=15m (silty sand layer), then the spacing L should be 15×1.5=22.5m (maximum not exceeding 30m) to avoid the water level in the middle area dropping due to excessive spacing. If there are important protected objects nearby (such as ancient buildings or subway tunnels), the spacing needs to be increased to L=R (100% overlap) to ensure the water level stability in key areas. The third step involves considering the density of the dewatering wells. Recharge wells are typically arranged "outside the dewatering wells" or "between the protected object and the dewatering wells," and the spacing must match the spacing of the dewatering wells. If the spacing between dewatering wells is 20m (for large pumping volumes), the spacing between recharge wells should be 15-20m to ensure that the pumping volume of each dewatering well can be replenished by the surrounding recharge wells. For long and narrow foundation pits (such as subway sections), recharge wells should be arranged linearly along both sides of the foundation pit, and the spacing should be controlled according to the "radius of influence in the direction of the shorter side."

[0078] Furthermore, when determining the recharge volume, it is necessary to "recharge as needed and adjust dynamically." The recharge volume needs to balance the "rainwater pumping volume" and the "aquifer recharge capacity" to avoid insufficient recharge leading to a drop in water level, and to prevent excessive recharge from causing surface uplift or piping. The determination logic is divided into two layers: "total volume control" and "single well control." The first layer, the total recharge volume, should not be less than 70%-90% of the rainwater pumping volume. The core of the total recharge volume (Q_total) is to "offset the groundwater loss caused by rainwater." It is necessary to first calculate the total pumping volume of the foundation pit (Q_pump), and then adjust it according to geological conditions. For example, if the total pumping volume of the foundation pit Q_pump = 1000 m³ / d (for sand and gravel layers), then the total recharge volume Q_total = 1000 × 0.85 = 850 m³ / d, ensuring that the groundwater "basically balances in and out." The second layer, single well reinjection volume: does not exceed the aquifer's "allowable reinjection intensity". The single well reinjection volume (q_single) must be controlled within the aquifer's tolerance range to avoid excessive pressure damaging the formation structure. This can be controlled through field tests: when reinjecting a single well, gradually increase the flow rate. If "surface uplift (>5mm / d)" or "sudden increase in reinjection pressure (indicating filter blockage or aquifer saturation)" occurs, then the current flow rate is the maximum allowable reinjection volume for a single well.

[0079] Furthermore, during the dynamic adjustment process, "water level monitoring" can be used as the core basis. The reinjection volume is not a fixed value and needs to be adjusted through real-time monitoring. Monitoring indicators can include: groundwater level in the protected area (which needs to be maintained within "original water level ± 0.5m"), surface subsidence (≤2mm / d), and water quality of the reinjection well (to avoid reinjection water carrying sediment and polluting the aquifer). Adjustment logic: If the water level in the protected area is 0.3m lower than the original water level, increase the total reinjection volume (or single well flow); if the water level is 0.5m higher than the original water level or surface uplift occurs, reduce the reinjection volume; if the reinjection pressure rises but the water level does not rise, the filter pipe needs to be cleaned (to prevent blockage).

[0080] In order to improve the safety of foundation pit engineering, this embodiment can also carry out water interception and open drainage treatment, that is, set up drainage ditches and collection wells in the foundation pit to remove surface rainwater and shallow seepage water at the bottom of the pit. As an auxiliary means of water-stopping / dewatering technology, it is suitable for shallow foundation pits or when the water volume is small.

[0081] Optionally, after arranging pressure relief wells based on the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, and using the pressure relief wells to discharge and stabilize the confined water, the method further includes: setting up a water interception barrier outside the excavation range of the foundation pit to intercept surface runoff around the site; setting up a drainage channel inside the foundation pit to guide groundwater seeping from the slope of the foundation pit and water accumulating at the bottom of the pit to a centralized collection point, wherein the drainage channel includes at least one of the following: an internal interception ditch or a drainage ditch, and the centralized collection point includes: a sump well; installing pumping and drainage equipment in the centralized collection point to continuously pump the collected water to the drainage system outside the foundation pit.

[0082] First, let me explain the design principle of the water interception and drainage system: "Source blocking + active diversion + mid-stage pumping". Through an artificially constructed drainage system, the natural hydraulic balance is broken, and harmful water bodies (surface water, groundwater, and stagnant water) inside and outside the foundation pit are controlled below the excavation working face, while preventing external water bodies from flowing into the foundation pit.

[0083] Specifically, this can be broken down into three key steps: Step 1, Water Interception: Blocking external water intrusion by setting up "water interception barriers" (such as external interception ditches) outside the excavation area of ​​the foundation pit to intercept surface runoff (rainwater, construction wastewater) and shallow groundwater around the site, preventing them from seeping into the foundation pit and reducing the amount of water collected in the foundation pit from the source. Step 2, Water Diversion: Guiding the internal water body to collect by setting up "drainage channels" (such as internal interception ditches and drainage ditches) inside the foundation pit (toe of the slope and around the bottom of the pit) to guide groundwater seeping from the foundation pit slope and water accumulating at the bottom of the pit to a centralized collection point (sump well), preventing water from stagnating at the excavation surface. Step 3, Drainage: Centralized pumping to lower the water level by installing pumping and drainage equipment in the sump well to continuously pump the collected water to the municipal drainage system outside the foundation pit (a drainage permit needs to be applied for in advance), ensuring that the water level in the foundation pit is always 0.5-1.0m lower than the excavation working surface, meeting the conditions for dry construction.

[0084] In addition, the design must take into account hydraulic gradient control: avoid excessive water level difference between inside and outside the pit, which may lead to slope seepage damage (such as piping and quicksand). Therefore, the location and depth of intercepting ditches and collection wells need to be calculated and determined in conjunction with the site's hydrogeological conditions (such as groundwater depth and soil permeability coefficient).

[0085] In addition, the water interception and drainage system can include four parts: water interception facilities, diversion facilities, water collection facilities, and pumping facilities. The location, size, and materials of each component need to be flexibly designed according to the scale of the foundation pit and hydrological conditions. For details, please refer to the contents shown in Table 1 below.

[0086] Table 1. Schematic diagram of the water interception and drainage system

[0087]

[0088]

[0089] The operation process of the water interception and drainage system can follow the principle of "build the drainage first, then excavate," and proceed synchronously and dynamically with the foundation pit excavation. The specific process may include the following steps:

[0090] Step 1, Preliminary Preparation: Hydrological Survey and Scheme Design. First, conduct a site hydrogeological survey to determine the groundwater level depth, soil permeability coefficient, and surface water catchment area, and determine the location, size, and pump parameters of intercepting ditches / collection wells (e.g., the single well yield can be calculated through pumping tests); prepare a special drainage plan, clarifying the construction sequence, equipment selection, and emergency measures (e.g., a temporary drainage plan for heavy rain).

[0091] Step 2: Construct an external interception ditch for the foundation pit (source interception). Excavate the external interception ditch according to the design location. After accepting the foundation elevation, lay a crushed stone cushion layer, and then pour concrete or build a brick wall (the ditch wall needs to be plastered to prevent leakage). The end of the ditch needs to be connected to the municipal drainage system (or a temporary sedimentation tank to avoid silt contamination of the municipal pipe network) to ensure that external water does not seep into the foundation pit.

[0092] Step 3: Construct the intercepting ditch and sump well within the foundation pit (constructed simultaneously with excavation). After the foundation pit is excavated to the first layer of soil (or after the slope is trimmed), first excavate the inner intercepting ditch at the toe of the slope and pour concrete or brickwork; excavate the sump wells according to the design spacing, build the well walls, and lay a crushed stone filter layer. After completion, connect the inner intercepting ditch and the sump well (to ensure smooth water flow).

[0093] Step 4: Install and test-run the drainage equipment. Place a submersible pump in the sump (the pump body must be submerged in water to avoid damage from running dry), and connect the outlet pipe (the pipe must be fixed to avoid collisions during excavation); start the pump for a test run and check: ① Whether the drainage is smooth (no pipe blockage or leakage); ② Whether the water level drop rate meets the design requirements (generally, run for 1-2 hours and observe whether the water level in the pit drops below the excavation surface); ③ Whether the standby pump switching is normal.

[0094] Step 5: Dynamic maintenance during foundation pit excavation. As the excavation depth increases, the sump pit should be deepened accordingly (deepen the sump pit by 0.5-1.0m before each excavation to ensure it remains below the excavation surface); clean the silt and sediment in the intercepting and drainage ditches daily (manual or small excavator cleaning is acceptable); regularly check the filter layer of the sump pit (replace the gravel if there is excessive silt) to prevent blockage; increase the pumping frequency during rainy days or when groundwater is abundant (e.g., turn on the backup pump); monitor the water level in the pit in real time (a water level gauge can be installed) to prevent the water level from rising.

[0095] Step 6: Stop drainage and dismantle the system. Once the foundation works (such as the cushion layer and bottom slab) in the pit are completed and the backfill soil is above the groundwater level (or meets the anti-buoyancy requirements), pumping can be gradually stopped. The system should be dismantled in the order of "dismantle equipment first, then dismantle structures": first remove the water pumps and pipelines, and then dismantle the internal intercepting ditch and sump in sections (the pit space after dismantling should be backfilled with plain soil and compacted).

[0096] In this embodiment, based on the calculated seepage flow rate and conditions of the foundation pit, the layout of the pressure relief wells is completed. After controlling the discharge and pressure equalization of confined water using the pressure relief wells, a series of additional safety monitoring measures are implemented. Optionally, after arranging the pressure relief wells according to the calculated seepage flow rate and conditions of the foundation pit, and using the pressure relief wells to discharge and equalize confined water, the following additional measures are taken: setting monitoring points at easily deformable parts of the foundation pit slope, wherein easily deformable parts include at least one of the following: the top of the foundation pit slope, the building foundation, and the toe of the foundation pit slope; monitoring the excavation process of the foundation pit using the monitoring points, and determining whether a groundwater inrush hazard has occurred based on the monitoring results; and setting water level gauges at the centralized collection points of the foundation pit to observe water level changes. This not only helps to assess the safety of the foundation pit excavation process in real time, but also enables rapid response to potential groundwater inrush hazards.

[0097] In this embodiment, monitoring points were added to areas prone to deformation, such as the top of the foundation pit slope, the perimeter of the building foundation, and the toe of the foundation pit slope. The placement of these monitoring points took into account specific geological conditions and engineering requirements, effectively capturing the changing trends of key indicators such as slope displacement and settlement. Using these monitoring points, this embodiment provided close monitoring of the entire foundation pit excavation process. The monitoring data provided real-time feedback, enabling the construction team to quickly adjust construction strategies based on the monitoring results, preventing or mitigating the adverse effects of groundwater inrush on the project.

[0098] At the centralized collection point of the foundation pit, a water level gauge is installed in this embodiment to monitor water level changes in real time. The data recorded by the water level gauge helps to understand the dynamic change pattern of water level in the foundation pit, ensure the effective operation of the drainage system, and also provide early warning of abnormal water level rises, so as to take timely measures to avoid the risk of sudden surge.

[0099] In addition, this embodiment can also install a flow meter at the drainage ditch to measure the pumping flow rate and verify the accuracy of the model calculations. A backup generator set and backup well points are also provided for emergency use.

[0100] The following describes in detail another optional implementation method.

[0101] This invention provides a method for controlling groundwater in foundation pits. Taking the Weishan Third-Line Ship Lock foundation pit project as an example, the method includes the following steps:

[0102] S1: Determine the safety level of the foundation pit based on the degree of impact on the project after the foundation pit is damaged.

[0103] The foundation pit of the Weishan Third Line Ship Lock is about 245m long and 200m wide, with an area of ​​53,974m2. The excavation depth is 11.0m-16.0m. The structures inside the foundation pit need to be constructed dry, and the construction period is estimated to be 8 years.

[0104] According to the "Technical Specification for Foundation Pit Support" (JGJ 120-2012) and the "Technical Specification for Building Slope Engineering" (GB50330-2013), foundation pits with a serious impact on the surrounding environment or the construction safety of the main structure, affecting more than 30% of the total construction period, are classified as Class I foundation pits; foundation pits with a serious impact on the surrounding environment or the construction safety of the main structure, affecting 10%-30% of the total construction period, are classified as Class II foundation pits; and foundation pits with a serious impact on the surrounding environment or the construction safety of the main structure, affecting less than 10% of the total construction period, are classified as Class III foundation pits, with an importance coefficient of 1.1.

[0105] S2: Analyze the distribution characteristics of soil and rock layers and the type of groundwater, and determine the pressure of confined water.

[0106] According to the geological survey report, the soil layers distributed from top to bottom include silty clay, silt, and fine sand. Pumping tests were conducted to determine the permeability coefficients of each soil layer. The silty clay has a permeability coefficient of 10⁻⁷ cm / s, making it essentially impermeable; the fine sand has a permeability coefficient of 10⁻⁴ cm / s to 10⁻³ cm / s, making it a moderately permeable layer. Borehole tests revealed a groundwater elevation of 3.80 m and a confined aquifer elevation ranging from -14.00 to -9.38 m. The aquifer media are mainly silt and fine sand, with an average confined aquifer head of approximately 13.15 m. The confined aquifer in the site area is connected to the surface water in the floodplain, and the confined aquifer head varies with the flood level. The site primarily receives lateral recharge from the surface water in the floodplain, exhibiting a stagnant flow pattern.

[0107] Furthermore, this embodiment can directly obtain water level or pressure data by drilling to expose the confined aquifer. The core is to utilize the "conversion relationship between confined water level (piezometric water level) and pressure" (formula: p=ρgh, where p is the confined water pressure, ρ is the groundwater density, g is the gravitational acceleration, and h is the "height difference between the piezometric water level and the top plate of the aquifer", i.e., the confined water head height).

[0108] Confined aquifer top elevation: When the permeability of two soil layers is greater than 10 times, the top elevation of the layer with the larger permeability coefficient is the top of the aquifer. In this project, it refers to the top of the silty sand, and its elevation is the confined aquifer top elevation.

[0109] Average confined water head: Due to the uneven distribution of strata, the elevation of the confined water top plate varies in different locations, and in this project it is a range (-14.00 to -9.38m); the confined water head is evaluated as the average of the confined water heads revealed by multiple boreholes.

[0110] S3: Perform a verification analysis of the confined water breaching the bottom of the pit (sudden surge) to obtain the elevation of the overlying soil layer.

[0111] According to the project construction requirements, the bottom elevation of the foundation pit is -9.35m, the bottom dimensions are 101m × 139m = 14039m², and the excavation depth is approximately 3.8m - (-9.35m) = 13.15m. The excavation cross-section is as follows: Figure 2 As shown (from top to bottom, there are soil layers such as silty clay, silt, and fine sand, and the bottom elevation of the excavation pit is -9.35).

[0112] According to the "Handbook of Foundation Pit Engineering" (Second Edition) published by China Building Industry Press, when an impermeable layer exists below the foundation pit and is located above a confined aquifer, it should be calculated whether the bottom of the pit will be eroded by the confined water. If erosion is possible, dewatering wells must be used to ensure safety. The calculation diagram is shown below. Figure 3 As shown, the calculation principle is that the self-weight pressure of the soil within the range from the bottom of the foundation pit to the upper interface of the confined aquifer (i.e., h+t) should be greater than the pressure of the confined water, and the safety factor should not be less than 1.20.

[0113]

[0114] In the formula: and These are the unit weights of the soil and groundwater (kN / m³), respectively; according to the geological survey report, =15.6KN / m 3 ; =10.00KN / m 3 ; The head of the pressurized water is 13.15m, according to the geological survey report.

[0115] in The elevation of the overlying soil layer is -9.38m + 10.12m = 0.74m. That is, when excavating to an elevation of 0.74m, measures must be taken to prevent piping from occurring when excavating further down.

[0116] S4: Conduct seepage stability analysis to determine the location and elevation of the cutoff curtain.

[0117] Because the elevation of the cutoff wall is crucial to the safety of the foundation pit, this embodiment uses three methods to calculate its bottom elevation and selects a conservative scheme as the bottom elevation of the cutoff wall.

[0118] The first method is based on the provisions of the "Handbook of Foundation Pit Engineering" (Second Edition) published by China Construction Industry Press:

[0119]

[0120] In the formula: and These are the buoyant unit weight of the soil and the unit weight of the groundwater (kN / m), respectively. According to construction needs, the water level in the foundation pit will be lowered to 1m below the pit surface, i.e., t2 = 1m. h = 3.8m - (-10.35)m = 14.15m; Let the bottom elevation of the cutoff wall be x, then t = (-10.35) - x. =9.82KN / m 3 ; =10.00KN / m 3 .

[0121] Seeking = >3.00, where 3.0 is a requirement from the "Foundation Pit Engineering Manual". Based on the above formula, the bottom elevation of the cutoff wall is x = -24.90m.

[0122] According to Article C.0.2 of the "Technical Specification for Foundation Pit Support" (JGJ 120-2012), when the bottom of the suspended cutoff curtain is located in a gravelly soil, sandy soil, or silty soil aquifer, the soil stability of groundwater seepage in a homogeneous aquifer should meet the following formula. The simplified calculation diagram is shown in [the original text]. Figure 4 The specific calculation formula is as follows:

[0123] = ≥ =1.6

[0124] Based on the above formula, the elevation of the bottom of the water-cutting curtain is x = -21m.

[0125] The calculation method of a certain engineering team (3) is shown in the simplified calculation diagram below. Figure 5 The specific calculation formula is as follows:

[0126] = ≥1.5;

[0127] Based on the above formula, z = 20.6m, and the converted elevation is -9.38m - 20.6m = -29.98m.

[0128] According to the calculation methods in (1), (2), and (3), the bottom elevation of the cutoff wall is found to be -29.98m, which is rounded to -30m. To avoid sudden surges, the top elevation of the cutoff wall is 0.74m, as determined by S4. To avoid the impact of the excavation process on the cutoff wall, it is set at the 0.74m elevation next to the drainage ditch, forming a closed loop in the plane.

[0129] S5: Conduct a comparison and selection of water cutoff curtain schemes and determine the water cutoff curtain scheme.

[0130] (1) Continuous cement wall curtain scheme: Cement and other curing agents are mechanically mixed with the soil to form a continuous cement-soil pile wall (permeability coefficient ≤ 1). (7cm / s), suitable for soft soil, cohesive soil or sandy soil, depth usually ≤50m, low cost.

[0131] (2) High-pressure jet grouting curtain scheme: High-pressure jet cement slurry is used to cut and mix the soil to form a pile body, which can form a continuous curtain with a diameter of 0.6-2.0m. It is suitable for sand and gravel layers and complex strata, and the depth can reach more than 30m, but it causes slightly more disturbance to the surrounding soil.

[0132] (3) Diaphragm wall scheme: A deep trench is excavated using a trenching machine, and concrete is poured to form a continuous wall with an extremely low permeability coefficient (≤1). (cm / s), and as a support structure, it is suitable for ultra-deep foundation pits (≥30m), complex strata, or areas with sensitive surrounding environments (such as urban core areas), but the cost is relatively high.

[0133] (4) Construction method pile scheme: It consists of multi-axis mixing piles with steel sections inserted inside. The cement soil piles stop water and the steel sections bear the support force. It is suitable for medium and deep foundation pits (≤20m) in soft soil areas. It has both water-stopping and support functions, fast construction speed and recyclable steel sections.

[0134] (5) Steel sheet pile water cutoff curtain: suitable for sandy soil and water cutoff depth less than 24m. The steel sheet piles are recyclable.

[0135] Then, the selection of the water-cutting curtain scheme is based on factors such as safety, construction efficiency, environmental impact, and scenario-based selection. For example, in terms of safety, diaphragm walls: the concrete wall has good integrity, no joint hazards, can both stop water and withstand the lateral earth pressure of the foundation pit, and can even be used as a permanent structure, making it the first choice in deep foundation pits (>20m), high water levels, and complex geological conditions (such as sand and gravel layers). Continuous cement wall curtain schemes and pile method schemes: their safety is similar, each with its own emphasis. The continuous cement wall curtain scheme is superior in its "continuous and seamless" nature, suitable for soft soil areas with extremely high water-stopping requirements; the pile method scheme is superior in its "rigid-flexible combination," with steel sections providing lateral pressure resistance and cement soil ensuring water stoppage, suitable for medium-depth (10-18m) foundation pits. High-pressure jet grouting piles: safety depends on construction quality. The overlap between piles is crucial – if the soil layer is uneven (e.g., containing boulders), the spraying radius is prone to deviation, leading to leakage at the "cold joint," requiring subsequent re-spraying. This is suitable for shallow foundation pits (<10m) or as an auxiliary water stop (e.g., in conjunction with sheet piles). Sheet piles: the interlock is the main leakage point, especially for repeatedly used old piles (with worn interlocks). It is only suitable for temporary, shallow foundation pits (<8m) or clay areas with low permeability, requiring high-pressure grouting reinforcement for water stop.

[0136] After comparison, in terms of safety: diaphragm wall > continuous cement wall curtain scheme ≈ construction method pile scheme > high-pressure jet grouting pile > steel sheet pile.

[0137] For example, the priority selection of scenario-based solutions based on different project scenarios is as follows: Deep foundation pit (>20m) + high water level + ample construction period: choose diaphragm wall (safety first, can also serve as main structure); Medium depth (10-18m) + high environmental protection requirements + tight construction period: choose construction pile solution (balances safety, efficiency, and environmental protection, steel recycling saves costs); Soft soil area + high water-stopping requirements + large-area construction: choose continuous cement wall curtain solution (seamless water-stopping, suitable for soft soil); Shallow foundation pit (<10m) + narrow site + tight construction period: choose high-pressure jet grouting pile (compact equipment, fast construction); Temporary foundation pit (<8m) + recyclable + low pollution: choose steel sheet pile (highest efficiency, environmentally friendly, suitable for temporary projects).

[0138] Furthermore, Figure 6 This is a layout diagram of an optional cutoff curtain scheme according to an embodiment of the present invention. In the Weishan Third-Line Ship Lock foundation pit project, the depth of the cutoff curtain is: 0.74m - (-30.00) = 30.74m. The stratum consists of silt and sand layers, with relatively high pressure from confined water. Based on the cutoff curtain depth, stratum parameters, and groundwater type, the more economical continuous cement wall curtain scheme is selected.

[0139] Step S6: Establish a finite element method and use finite element software to calculate the seepage flow of the foundation pit.

[0140] (1) The model size is 100 times the curtain depth, i.e., 31-9.35=20.65m, and appropriately enlarged to 3000m×3000m.

[0141] (2) The elevation of each soil layer, permeability coefficient and the elevation of the cutoff curtain are shown in Table 2.

[0142] (3) Input the unit weight of each soil layer, the specific weight of water, and the water level data of each part.

[0143] The initial data for the unit weight of each soil layer, the unit weight of water, the water level at each location, and the groundwater level are determined based on the geological survey report; the initial stress state of the soil layer is determined by inputting the thickness, unit weight, and groundwater level of each soil layer, and is automatically calculated by the model.

[0144] (4) Divide the computational grid with a grid density of 0.5m.

[0145] (5) Calculate the seepage flow rate and obtain the distribution lines of different water levels and the seepage flow rate when the silt layer has different permeability coefficients: if the permeability coefficient of the silt is 4.27×10-3cm / s, the daily seepage flow rate is 9120m3, which is equivalent to an hourly flow rate of 380m3; if the permeability coefficient of the silt is 9.97×10-4cm / s, the daily seepage flow rate is 1725m3, which is equivalent to an hourly flow rate of 71.88m3.

[0146] Table 2 Calculation Parameter Table

[0147]

[0148] S7: Arrange pressure relief wells to discharge pressurized water and equalize pressure.

[0149] By using a pumping system to lower the groundwater level inside or outside the pit to below the excavation surface, seepage pressure can be reduced.

[0150] (1) Lightweight well point: The well point pipe with a diameter of 50-100mm is used to introduce groundwater into the well point pipe through vacuum negative pressure. It is suitable for shallow foundation pits (≤6m), cohesive soil or silty soil, with a water depth of 3-6m. The equipment is lightweight and low cost.

[0151] (2) Jet well point: High pressure water or air jet is used to form negative pressure pumping. It is suitable for medium-deep foundation pits (6-20m) and soil layers with low permeability (such as silty clay). The water depth can reach 10-20m.

[0152] (3) Well point: Use steel or concrete pipes with a diameter of 300-600mm as well pipes, and use deep well pumps for water pumping. It is suitable for deep foundation pits (≥20m), sandy soil or gravel layers and other water-rich strata. The single well has a large water output (up to 100-1000 m³ / d) and flexible water depth (up to 30m or more).

[0153] (4) Electroosmotic well points: for low-permeability formations such as cohesive soils (permeability coefficient < 1) (cm / s), by generating an electric field through electrodes to drive pore water to move toward the well point, combined with lightweight well point pumping, the problem of low efficiency of conventional dewatering is solved.

[0154] (5) Vacuum deep well dewatering: Applying vacuum negative pressure in the well enhances pumping efficiency. It is suitable for strata such as silt and sand that are prone to "well kick" and can reduce the drop in water level outside the pit.

[0155] To effectively reduce the confined water in the sand layer, the bottom elevation of the well should penetrate the silt layer and enter the sand layer by 2m. In this embodiment, the top elevation of the Weishan Third-Line Ship Lock well is 0.74m, and the bottom elevation is -16.98m-2m=-19m; the depth of the dewatering well is 0.74-(-19)=20.74m. The hourly seepage flow rate of the foundation pit in this project is 71.88m3-380m3; considering the destructive effect of confined water and the seepage flow rate, wellpoint dewatering with pipe wells is adopted. A pump with a pumping capacity of 100380m3 / h is selected, and one pump is placed at each of the four corners of the target foundation pit (a total of four pumps) to meet the requirements. See Figure 7 .

[0156] S8: Take supplementary measures to balance precipitation and environmental impact.

[0157] Measures such as recharge and open drainage are adopted to balance the environmental impact of foundation pit dewatering, ensure the safety of surrounding facilities, and drain water from the foundation pit.

[0158] S9: Set up monitoring facilities, formulate emergency plans, and ensure the safety of the foundation pit and construction.

[0159] Settlement and displacement monitoring points are installed at locations prone to deformation, such as the top of the slope, building foundations, and the toe of the foundation pit, and monitoring is conducted throughout the entire foundation pit construction process. Water level gauges are installed at well points to observe water level changes. Flow meters are installed at drainage ditches to measure pumping flow and verify the accuracy of model calculations. Backup generator sets and backup well points are provided for emergency use.

[0160] Through the embodiments of this invention, the stability of the foundation pit in a confined water environment can be significantly enhanced by accurately calculating the bottom elevation and location of the cutoff wall and combining it with the seepage stability analysis of the overlying soil elevation, effectively preventing safety risks such as bottom heave and slope slippage. By using finite element software models to simulate seepage in the foundation pit, this invention can accurately predict the seepage distribution at different water levels and rationally arrange pressure relief wells based on the calculation results, achieving effective control of the foundation pit seepage flow.

[0161] Based on the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, this invention intelligently plans the layout of the pressure relief wells to ensure the efficiency of pressurized water discharge and the pressure-reducing effect, thereby reducing the impact on the surrounding environment and improving the overall safety and construction efficiency of the project. By setting monitoring points at easily deformable parts of the foundation pit and using water level gauges at the collection wells, this invention can construct a real-time monitoring and early warning system to promptly detect and respond to risks such as sudden surges and abnormal water levels, ensuring the safe progress of foundation pit construction.

[0162] In addition, the embodiments of the present invention fully consider the impact on the environment when selecting the water interception curtain scheme and optimizing the layout strategy of the pressure relief wells. By adopting a scenario-based selection scheme, the problems of noise and mud pollution during construction are reduced, and the green sustainability of the project is improved.

[0163] The automated calculation process and optimized layout scheme provided by the embodiments of the present invention reduce the time consumption of traditional manual calculation and experience judgment, accelerate the formulation and implementation of groundwater control plans, and help shorten the construction cycle of foundation pits.

[0164] The following is a detailed description with reference to another embodiment.

[0165] Example 2

[0166] The groundwater control device for a confined water foundation pit provided in this embodiment includes multiple implementation units, each of which corresponds to a specific implementation step in Embodiment 1 above.

[0167] Figure 8 This is a schematic diagram of an optional groundwater control device for a confined aquifer according to an embodiment of the present invention, as shown below. Figure 8 As shown, the groundwater control device for the confined water foundation pit may include: a confined water pressure calculation unit 81, an overlying soil elevation calculation unit 82, a water cutoff curtain scheme determination unit 83, and a confined water pressure relief unit 84.

[0168] Among them, the confined water pressure calculation unit 81 is used to analyze the distribution characteristics of soil and rock layers and the type of groundwater, and to calculate the confined water pressure of the foundation pit.

[0169] The overlying soil elevation calculation unit 82 is used to perform verification analysis on the confined water pressure to erode the bottom of the pit and obtain the overlying soil elevation. The overlying soil elevation is used to determine the excavation limit elevation for which measures need to be taken to prevent piping.

[0170] The cutoff curtain scheme determination unit 83 is used to perform seepage stability analysis based on the elevation of the overlying soil layer, determine the location and bottom elevation of the cutoff curtain, and generate a cutoff curtain scheme.

[0171] The confined water pressure relief unit 84 is used to calculate the seepage flow of the foundation pit using finite element software model, arrange pressure relief wells according to the calculation results of the foundation pit seepage flow and the foundation pit conditions, and use the pressure relief wells to discharge and stabilize the confined water.

[0172] The aforementioned groundwater control device for confined water foundation pits can analyze the distribution characteristics of soil and rock layers and the type of groundwater through the confined water pressure calculation unit 81, calculate the confined water pressure of the foundation pit, and perform verification analysis on the confined water erosion of the pit bottom based on the confined water pressure through the overlying soil elevation calculation unit 82 to obtain the overlying soil elevation. The overlying soil elevation is used to determine the excavation limit elevation for which measures need to be taken to prevent piping. Based on the overlying soil elevation, the cutoff wall scheme determination unit 83 performs seepage stability analysis to determine the location and bottom elevation of the cutoff wall and generate the cutoff wall scheme. The confined water pressure relief unit 84 uses a finite element software model to calculate the seepage flow of the foundation pit, and arranges pressure relief wells according to the calculation results and conditions of the foundation pit. The pressure relief wells are used to discharge and stabilize the confined water. In this embodiment, the pressure of confined water can be used to perform a verification analysis of the confined water breach at the bottom of the pit, thereby obtaining the elevation of the overlying soil layer. Then, the optimal location and depth of the cutoff wall can be determined to ensure the safety and stability of the foundation pit in a confined water environment, effectively preventing bottom heave and slope instability. By selecting the most suitable cutoff wall scheme and type, resource waste caused by over-design can be avoided. Finally, finite element software is used to perform seepage analysis to accurately calculate the seepage flow in the foundation pit, guiding the design of the depressurization wells, ensuring the dewatering effect and preventing abnormal drop in the water level outside the pit, improving the efficiency of depressurization well layout, and improving the accuracy of groundwater control in foundation pit engineering. This solves the technical problem of low efficiency in designing depressurization wells through trial and error when groundwater control is not possible in foundation pit engineering.

[0173] Optionally, the confined water pressure calculation unit includes: a groundwater elevation acquisition module, used to determine the groundwater elevation in the confined aquifer through borehole tests; and a confined water pressure calculation module, used to calculate the confined water pressure of the foundation pit based on the groundwater density, gravitational acceleration value, and confined water head height.

[0174] Optionally, the overlying soil elevation calculation unit includes: an excavation depth calculation module, used to calculate the excavation depth based on the groundwater elevation and the bottom elevation of the foundation pit; a confined water pressure value calculation module, used to determine the unit weight value of groundwater and the hydraulic head value of confined water based on the geological survey report, and to determine the pressure value of confined water by combining the unit weight value of groundwater and the hydraulic head value of confined water; a soil self-weight pressure value calculation module, used to determine the soil unit weight value based on the geological survey report, and to calculate the self-weight pressure value of the soil within the range from the bottom of the foundation pit to the upper interface of the confined water layer by combining the soil unit weight value, the pressure value of confined water and a preset safety factor; and an overlying soil elevation calculation module, used to calculate the overlying soil elevation based on the self-weight pressure value of the soil within the range from the bottom of the foundation pit to the upper interface of the confined water layer and the excavation depth.

[0175] Optionally, the water-cutting curtain scheme determination unit includes: a water-cutting curtain bottom elevation calculation module, used to calculate the water-cutting curtain bottom elevation based on the groundwater elevation in the confined aquifer, the buoyancy of the soil, and the unit weight of the groundwater; a water-cutting curtain bottom elevation determination module, used to determine the final water-cutting curtain bottom elevation based on the water-cutting curtain bottom elevation and the anti-surge safety range; and a water-cutting curtain location calculation module, used to calculate the water-cutting curtain location based on the overlying soil elevation and the final water-cutting curtain bottom elevation.

[0176] Optionally, the cutoff wall scheme determination unit further includes: a multi-cutoff wall scheme determination module, used to determine the continuous cement wall cutoff wall scheme, high-pressure jet grouting pile cutoff wall scheme, underground continuous wall cutoff wall scheme, construction method pile cutoff wall scheme, and steel sheet pile cutoff wall scheme based on the final cutoff wall bottom elevation and cutoff wall location; a cutoff wall scheme scoring module, used to score each cutoff wall scheme from the perspectives of safety, construction efficiency, environmental impact, and scenario-based selection; and a cutoff wall scheme selection module, used to select the cutoff wall scheme with the highest comprehensive score as the final cutoff wall scheme.

[0177] Optionally, the confined water pressure relief unit includes: a model size definition module, used to define the model size of the finite element software model based on the curtain depth at the location of the cutoff curtain; a soil layer data acquisition module, used to acquire the soil unit weight, groundwater unit weight, and water level data at various locations for each soil layer based on the geological survey report; an input module, used to input the soil unit weight, groundwater unit weight, water level data at various locations, and initial groundwater level data for each soil layer into the finite element software model; a mesh generation module, used to mesh the finite element software model using a mesh density; and a foundation pit seepage flow calculation module, used to calculate the seepage flow of the foundation pit using the meshed finite element software model, and obtain the distribution lines of different water levels and the seepage flow for different permeability coefficients of the silty sand layer.

[0178] Optionally, the confined water pressure relief unit includes: a pressure relief well scheme selection module, used to select the pressure relief well scheme to be arranged based on the calculation results of the seepage flow of the foundation pit and the conditions of the foundation pit, and to set up a water pump to pump water to the target location of the foundation pit.

[0179] Optionally, the groundwater control device for confined aquifer foundation pits further includes: a filter pipe data acquisition module, used to acquire the depth from the surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well after arranging pressure relief wells according to the foundation pit seepage flow calculation results and foundation pit conditions, and using the pressure relief wells to discharge and stabilize the confined water; a recharge well total depth calculation module, used to calculate the total depth of the recharge wells based on the depth from the surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well; and a recharge well spacing calculation module, used to calculate the recharge influence radius of a single well, combined with the single well recharge influence radius... The system includes a recharge well spacing module, a recharge total volume determination module, a single well recharge volume determination module, a recharge well setting ...

[0180] Optionally, the groundwater control device for confined water foundation pits further includes: a water interception barrier setting module, used to set up pressure relief wells according to the calculation results of the seepage flow of the foundation pit and the conditions of the foundation pit, and after the pressure relief wells are used to discharge and stabilize the confined water, a water interception barrier is set up outside the excavation range of the foundation pit to intercept the surface runoff around the site; a diversion channel setting module, used to set up diversion channels inside the foundation pit to guide the groundwater seeping from the slope of the foundation pit and the water accumulated at the bottom of the pit to a centralized collection point, wherein the diversion channels include at least one of the following: internal interception ditch and drainage ditch, and the centralized collection point includes: a sump well; and a pumping and drainage equipment installation module, used to install pumping and drainage equipment in the centralized collection point to continuously pump the collected water to the drainage system outside the foundation pit.

[0181] Optionally, the groundwater control device for confined water foundation pits further includes: a monitoring point setting module, used to set monitoring points at easily deformable parts of the foundation pit slope after arranging pressure relief wells according to the calculation results of the foundation pit seepage flow and the foundation pit conditions, and using the pressure relief wells to discharge and stabilize the confined water; wherein the easily deformable parts include at least one of the following: the top of the foundation pit slope, the building foundation, and the toe of the foundation pit slope; a monitoring module, used to monitor the excavation process of the foundation pit using the monitoring points, and determine whether a groundwater surge danger occurs based on the monitoring results; and a water level gauge setting module, used to set water level gauges at the centralized collection points of the foundation pit, and use the water level gauges to observe water level changes.

[0182] The aforementioned groundwater control device for confined water foundation pits may also include a processor and a memory. The aforementioned confined water pressure calculation unit 81, overlying soil elevation calculation unit 82, water cutoff curtain scheme determination unit 83, and confined water pressure relief unit 84 are all stored in the memory as program units. The processor executes the aforementioned program units stored in the memory to realize the corresponding functions.

[0183] The aforementioned processor contains a kernel, which retrieves the corresponding program units from memory. One or more kernels can be configured, and groundwater control in confined water foundation pits can be achieved by adjusting kernel parameters.

[0184] The aforementioned memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0185] According to another aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored computer program, wherein, when the computer program is running, it controls the device where the computer-readable storage medium is located to execute the groundwater control method for any one of the above embodiments of the first embodiment.

[0186] According to another aspect of the present invention, an electronic device is also provided, including one or more processors and a memory, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the groundwater control method for confined water foundation pits as described in any of the above embodiments.

[0187] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the groundwater control method for confined water foundation pits described in various embodiments of this application.

[0188] This application also provides a computer program product, including a non-volatile computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the groundwater control method for confined water foundation pits described in various embodiments of this application.

[0189] Figure 9 This is a hardware structure block diagram of an electronic device (or mobile device) for implementing a groundwater control method for a confined water foundation pit according to an embodiment of the present invention. Figure 9 As shown, an electronic device may include one or more ( Figure 9The processor (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and memory 904 for storing data are illustrated using 902a, 902b, ..., 902n. In addition, it may include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of the I / O interface), a network interface, a keyboard, a power supply, and / or a camera. Those skilled in the art will understand that... Figure 9 The structure shown is for illustrative purposes only and does not limit the structure of the electronic device described above. For example, the electronic device may also include components that are more... Figure 9 The more or fewer components shown, or having the same Figure 9 The different configurations shown.

[0190] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0191] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0192] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0193] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0194] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0195] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0196] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for controlling groundwater in a confined aquifer foundation pit, characterized in that, include: Analyze the distribution characteristics of soil and rock layers and the type of groundwater, and calculate the confined water pressure of the foundation pit; Based on the pressure of the confined water, a verification analysis is performed to determine the bottom of the pit from the confined water erosion, and the elevation of the overlying soil layer is obtained. The elevation of the overlying soil layer is used to determine the excavation limit elevation at which measures need to be taken to prevent piping. Based on the elevation of the overlying soil layer, a seepage stability analysis is performed to determine the location and bottom elevation of the cutoff curtain and generate a cutoff curtain scheme. The seepage flow rate of the foundation pit is calculated using a finite element software model. Based on the calculation results and the conditions of the foundation pit, pressure relief wells are arranged to discharge and stabilize the confined water.

2. The groundwater control method according to claim 1, characterized in that, The steps for analyzing the distribution characteristics of soil and rock layers and the type of groundwater, and calculating the confined water pressure of the foundation pit, include: The groundwater elevation in confined aquifers was determined through borehole tests. The confined water pressure of the foundation pit is calculated based on the groundwater density, gravitational acceleration, and confined water head.

3. The groundwater control method according to claim 2, characterized in that, Based on the aforementioned confined water pressure, the steps for verifying and analyzing the confined water breach at the bottom of the pit and obtaining the elevation of the overlying soil layer include: Calculate the excavation depth based on the groundwater elevation and the bottom elevation of the foundation pit; The density value of groundwater and the hydraulic head value of confined water are determined based on the geological survey report, and the pressure value of confined water is determined by combining the density value of groundwater and the hydraulic head value of confined water. Based on the geological survey report, the soil weight value is determined. Combining the soil weight value, the pressure value of the confined water, and the preset safety factor, the self-weight pressure value of the soil in the range from the bottom of the foundation pit to the upper interface of the confined water layer is calculated. The elevation of the overlying soil layer is calculated based on the self-weight pressure of the soil within the range from the bottom of the foundation pit to the upper interface of the confined aquifer and the excavation depth.

4. The groundwater control method according to claim 2, characterized in that, Based on the elevation of the overlying soil layer, the steps of performing seepage stability analysis, determining the location and bottom elevation of the cutoff wall, and generating a cutoff wall scheme include: The bottom elevation of the cutoff curtain is calculated based on the groundwater elevation in the confined aquifer, the buoyancy of the soil, and the unit weight of the groundwater. Based on the bottom elevation of the cutoff curtain and the safety range for preventing sudden surges, the final bottom elevation of the cutoff curtain is determined. The location of the cutoff curtain is calculated based on the elevation of the overlying soil layer and the final bottom elevation of the cutoff curtain.

5. The groundwater control method according to claim 4, characterized in that, The steps of performing seepage stability analysis based on the elevation of the overlying soil layer, determining the location and bottom elevation of the cutoff wall, and generating a cutoff wall scheme also include: Based on the final bottom elevation and location of the cutoff curtain, the following schemes are determined: continuous cement wall cutoff curtain, high-pressure jet grouting pile cutoff curtain, underground continuous wall cutoff curtain, construction method pile cutoff curtain, and steel sheet pile cutoff curtain. Each water cutoff curtain scheme was scored based on safety, construction efficiency, environmental impact, and scenario-based selection. The water-cutting curtain scheme with the highest comprehensive score was selected as the final water-cutting curtain scheme.

6. The groundwater control method according to claim 1, characterized in that, The steps for calculating the seepage flow rate of a foundation pit using finite element software models include: The model dimensions of the finite element software model are defined based on the curtain depth at the location of the water-cutting curtain. Based on the geological survey report, obtain the soil unit weight, groundwater specific weight, and water level data for each soil layer; The unit weight of each soil layer, the specific weight of the groundwater, the water level data of each location, and the initial data of the groundwater level are input into the finite element software model. The finite element software model is meshed using a specific mesh density. The seepage flow rate of the foundation pit was calculated using the finite element software model after meshing, and the distribution lines of different water levels and the seepage flow rate for different permeability coefficients of the silty sand layer were obtained.

7. The groundwater control method according to claim 1, characterized in that, Based on the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, a pressure relief well is arranged. The steps for discharging confined water and stabilizing the pressure using the pressure relief well include: Based on the calculation results of the seepage flow in the foundation pit and the conditions of the foundation pit, a plan for relieving pressure wells to be arranged is selected, and a water pump is set up to pump water from the target location of the foundation pit.

8. The groundwater control method according to claim 1, characterized in that, After arranging pressure relief wells based on the calculated seepage flow rate and conditions of the foundation pit, and using these wells to discharge confined water and equalize pressure, the process also includes: Obtain the depth from the surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well. The total depth of the reinjection well is calculated based on the depth from the surface to the top of the filter pipe, the length of the filter pipe, and the length of the sedimentation section from the bottom of the filter pipe to the bottom of the well. Calculate the influence radius of a single well's recharge, and determine the spacing between recharge wells by combining the influence radius of a single well's recharge, the pre-set overlap range of the influence range of adjacent wells, and the layout density of dewatering wells; Obtain the total pumping volume of the foundation pit, and determine the total amount of recharge based on the total pumping volume of the foundation pit; The recharge volume per well is determined based on the total recharge volume and the allowable recharge intensity of the aquifer. Based on the total depth of the recharge wells, the spacing between the recharge wells, and the recharge volume of a single well, recharge wells are set up around the precipitation area. The recharge wells are used to inject clean water into the ground to form a water level barrier to offset the surrounding soil settlement caused by precipitation.

9. The groundwater control method according to claim 1, characterized in that, After arranging pressure relief wells based on the calculated seepage flow rate and conditions of the foundation pit, and using these wells to discharge confined water and equalize pressure, the process also includes: A water interception barrier is set up outside the excavation area of ​​the foundation pit to intercept surface runoff around the site. A drainage channel is set up inside the foundation pit to guide groundwater seeping from the slope of the foundation pit and water accumulating at the bottom of the pit to a centralized collection point. The drainage channel includes at least one of the following: an internal intercepting ditch and a drainage ditch. The centralized collection point includes: a water collection well. A pumping and drainage device is installed at the centralized collection point to continuously pump the collected water to the drainage system outside the foundation pit.

10. The groundwater control method according to claim 1, characterized in that, After arranging pressure relief wells based on the calculated seepage flow rate and conditions of the foundation pit, and using these wells to discharge confined water and equalize pressure, the process also includes: Monitoring points are set at the easily deformable parts of the slope of the foundation pit, wherein the easily deformable parts include at least one of the following: the top of the slope of the foundation pit, the foundation of the building, and the toe of the slope of the foundation pit; The excavation process of the foundation pit is monitored using the monitoring points, and the risk of groundwater inrush is determined based on the monitoring results. A water level gauge is installed at the centralized collection point of the foundation pit to observe changes in water level.

11. A groundwater control device for a confined aquifer foundation pit, characterized in that, include: The confined water pressure calculation unit is used to analyze the distribution characteristics of soil and rock layers and the type of groundwater, and to calculate the confined water pressure of the foundation pit. The overlying soil elevation calculation unit is used to perform verification analysis on the confined water pressure to erode the bottom of the pit and obtain the overlying soil elevation. The overlying soil elevation is used to determine the excavation limit elevation at which measures need to be taken to prevent piping. The water cutoff curtain scheme determination unit is used to perform seepage stability analysis based on the elevation of the overlying soil layer, determine the location and bottom elevation of the water cutoff curtain, and generate a water cutoff curtain scheme. The confined water pressure relief unit is used to calculate the seepage flow of the foundation pit using finite element software model, arrange pressure relief wells according to the calculation results of the foundation pit seepage flow and the foundation pit conditions, and use the pressure relief wells to discharge and stabilize the confined water.

12. An electronic device, characterized in that, It includes one or more processors and a memory, the memory being used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors cause the one or more processors to implement the groundwater control method for confined water foundation pits according to any one of claims 1 to 10.

13. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the groundwater control method for confined water foundation pits as described in any one of claims 1 to 10.

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