Method for calculating water head difference between two sides of foundation pit curtain by considering underground water choked flow effect

Abstract

The invention discloses a foundation pit curtain two-side water head difference calculation method considering an underground water choked flow effect, which comprises the following steps of: obtaining water head difference influence factors on two sides of a foundation pit waterproof curtain and two sides of a subway station; the water head difference influence factors comprise the permeability coefficient ratio of the confined aquifer, the depth of a subway station, the distance between the subway station and a foundation pit and the thickness of the confined aquifer; based on numerical simulation, a water head difference calculation formula on the two sides of the foundation pit waterproof curtain and a water head difference calculation formula on the two sides of the subway station are constructed respectively; and on the basis of all influence factors of the water head difference, the water head difference calculation formulas of the two sides of the foundation pit waterproof curtain and the water head difference calculation formulas of the two sides of the subway station are corrected in sequence, and the corrected water head difference calculation formulas of the two sides of the foundation pit waterproof curtain and the corrected water head difference calculation formulas of the two sides of the subway station are obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of water level monitoring inside and outside a foundation pit, and in particular relates to a method for calculating the water head difference on both sides of a foundation pit curtain taking into account the groundwater flow resistance effect. Background Art

[0002] In densely populated urban environments, foundation pit construction (dewatering and excavation) can easily induce deformation of the surrounding environment of the foundation pit. Dewatering of foundation pits in water-rich strata is an essential part of foundation pit construction. Dewatering in the pit will cause the groundwater outside the pit to drop, thus causing deformation of the surrounding environment. In order to reduce the subsidence of the soil outside the pit caused by precipitation and ensure the safety of earthwork excavation in the pit, water-stop curtains are often used to block the subsidence of the soil outside the pit and the drop in water level. The water-stop curtain can block the seepage of groundwater outside the pit into the pit, so the water level outside the pit drops slowly, and the water level drop outside the pit is significantly less than the water level drop inside the pit, so there is a significant head difference on both sides of the water-stop curtain. In addition, the existence of existing underground structures will also have a certain impact on the foundation pit itself. For example, during the dewatering process of the foundation pit, the adjacent underground structures outside the pit will block the seepage of groundwater outside the pit into the pit, so that the distribution curve of groundwater inside and outside the pit is interrupted into three sections. It can be seen that there is a head difference on both sides of the foundation pit water-stop curtain and the existing underground structure, and this barrier effect is often ignored in the existing foundation pit design and construction process.

[0003] In actual foundation pit projects, water level observation wells are often set up inside and outside the pit to observe the changes in water level during the foundation pit dewatering process in real time. If the observation well cannot be set up outside the pit due to limited site conditions or the observation well is damaged during the foundation pit construction, the changes in water level outside the pit cannot be observed through the water level observation well outside the pit, which will affect the engineers' inability to accurately assess the depth of groundwater level drop inside and outside the pit, and may induce deformation of neighboring buildings outside the pit.

[0004] In response to this problem, Wu Yongxia derived an analytical solution that only considers the water head difference on both sides of the water-stop curtain and the water level distribution inside and outside the pit under the water-stop effect of the foundation pit water-stop curtain, but does not consider the water-stop effect of the adjacent underground structure. Therefore, it is necessary to propose a method for calculating the water head difference on both sides of the foundation pit curtain considering the groundwater flow resistance effect. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a method for calculating the water head difference on both sides of the foundation pit curtain taking into account the groundwater flow resistance effect, so as to solve the problems existing in the above prior art.

[0006] To achieve the above object, the present invention provides a method for calculating the water head difference on both sides of a foundation pit curtain taking into account the groundwater flow resistance effect, comprising the following steps:

[0007] Obtaining the factors affecting the water head difference on both sides of the foundation pit water-stop curtain and on both sides of the subway station, wherein the factors affecting the water head difference include the permeability coefficient ratio of the confined aquifer, the depth of the subway station, the distance between the subway station and the foundation pit, and the thickness of the confined aquifer;

[0008] Based on numerical simulation, the calculation formulas for the water head difference on both sides of the foundation pit water-stop curtain and the water head difference on both sides of the subway station are constructed respectively;

[0009] Based on various influencing factors of the water head difference, the water head difference calculation formulas on both sides of the foundation pit water-stop curtain and the water head difference calculation formulas on both sides of the subway station are modified in turn;

[0010] Based on the revised calculation formula for the water head difference on both sides of the foundation pit water-stop curtain and the revised calculation formula for the water head difference on both sides of the subway station, the corresponding water head difference on both sides of the foundation pit water-stop curtain and the water head difference on both sides of the subway station are obtained.

[0011] Optionally, the factors affecting the water head difference on both sides of the foundation pit water-stop curtain and on both sides of the subway station also include the ratio of the depth of the water-stop curtain inserted into the confined aquifer to the thickness of the aquifer.

[0012] Optionally, the process of sequentially correcting the head difference calculation formula on both sides of the foundation pit water-stop curtain based on various influencing factors of the head difference includes:

[0013] The first correction coefficient of the foundation pit water-stop curtain is obtained based on the permeability coefficient ratio of the confined aquifer, the second correction coefficient of the foundation pit water-stop curtain is obtained based on the depth of the subway station, the third correction coefficient of the foundation pit water-stop curtain is obtained based on the distance between the subway station and the foundation pit, and the fourth correction coefficient of the foundation pit water-stop curtain is obtained based on the thickness of the confined aquifer; based on the first correction coefficient, the second correction coefficient, the third correction coefficient and the fourth correction coefficient of the foundation pit water-stop curtain, the calculation formula for the water head difference on both sides of the foundation pit water-stop curtain is corrected.

[0014] Optionally, the corrected calculation formula for the water head difference on both sides of the foundation pit water-stop curtain is as follows:

[0015] Δh A1A2(总) =Δh A1A2 / α1α2α3α4,

[0016] in,

[0017] α1α2α3α4=2.9J -0.6 (0.85+0.005H)(0.96+0.43e -D / 16.24 )(0.59+3.1e -b / 6.6 ),

[0018]

[0019] Wherein, J is the permeability ratio of the confined aquifer, α1 is the first correction coefficient of the foundation pit water-stop curtain, H is the depth of the subway station, α2 is the second correction coefficient of the foundation pit water-stop curtain, D is the distance between the subway station and the foundation pit, α3 is the third correction coefficient of the foundation pit water-stop curtain, b is the thickness of the confined aquifer, α4 is the fourth correction coefficient of the foundation pit water-stop curtain, and b bd It is the ratio of the depth of the water-stop curtain inserted into the confined aquifer to the thickness of the aquifer.

[0020] Optionally, the process of sequentially correcting the water head difference calculation formula on both sides of the subway station based on various influencing factors of the water head difference includes:

[0021] A first correction coefficient of the subway station is obtained based on the permeability coefficient ratio of the confined aquifer, a second correction coefficient of the subway station is obtained based on the depth of the subway station, a third correction coefficient of the subway station is obtained based on the thickness of the confined aquifer, and a fourth correction coefficient of the subway station is obtained based on the distance between the subway station and the foundation pit; based on the first correction coefficient, the second correction coefficient, the third correction coefficient and the fourth correction coefficient of the subway station, the head difference calculation formula on both sides of the subway station is corrected.

[0022] Optionally, the corrected water head difference calculation formula on both sides of the subway station is as follows:

[0023] Δh B1B2(总) =Δh B1B2 / β1β2β3β4,

[0024] in,

[0025] Δh B1B2 =-0.4b bd +2.27,

[0026] β1β2β3β4=(A1+B1b bd )(0.78+885×0.75 H )(A2+B2b bd )(A3+B3b bd ),

[0027]

[0028] Wherein, J is the permeability ratio of the confined aquifer, β1 is the first correction coefficient of the subway station, H is the depth of the subway station, β2 is the second correction coefficient of the subway station, D is the distance between the subway station and the foundation pit, β3 is the third correction coefficient of the subway station, b is the thickness of the confined aquifer, β4 is the fourth correction coefficient of the subway station, and b bd It is the ratio of the depth of the water-stop curtain inserted into the confined aquifer to the thickness of the aquifer.

[0029] The present invention also provides a computer device, comprising a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method.

[0030] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method are implemented.

[0031] The present invention also provides a computer program product, comprising a computer program, which implements the steps of the method when executed by a processor.

[0032] Compared with the prior art, the present invention has the following advantages and technical effects:

[0033] Comprehensive analysis of the barrier effect of subway stations: Through preliminary analysis of the influencing factors of the head difference on both sides of the foundation pit enclosure and on both sides of the station under the barrier effect of the subway station, the present invention can accurately identify and consider various influencing factors, especially the relationship and interaction between the subway station and the foundation pit, which provides a solid theoretical basis for subsequent research.

[0034] Establishing a three-dimensional numerical model: This invention considers the three-dimensional numerical model of foundation pit dewatering that takes into account the barrier effect of subway stations, which more comprehensively reflects the complexity of hydrogeological conditions in actual projects. Through three-dimensional numerical simulation, the change of water head difference during foundation pit dewatering can be predicted more accurately, providing accurate data support for engineering design and construction.

[0035] Multi-parameter analysis and optimization design: This invention establishes a three-dimensional finite difference model of multiple parameters such as the permeability ratio of the confined aquifer, the depth of the subway station, the distance between the subway station and the foundation pit, and the thickness of the confined aquifer, which can comprehensively analyze the influence of various influencing factors on the head difference and find the internal connection between different parameters. This method has strong adaptability and flexibility, and can be optimized according to specific conditions.

[0036] Calculation formula for water head difference: The present invention further deduces the calculation formula for water head difference on both sides of the foundation pit enclosure and on both sides of the existing station, providing a simple and effective calculation method. This enables the water head difference to be calculated quickly and accurately in actual engineering applications, providing a basis for the design and optimization of foundation pit dewatering schemes.

[0037] Improve engineering safety and economy: The present invention can effectively prevent foundation pit deformation or safety accidents caused by excessive head difference by accurately calculating the head difference, thereby improving the safety of the project. At the same time, optimizing the foundation pit dewatering scheme helps save costs and improve construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0039] Figure 1 A water level distribution curve diagram of the second confined aquifer according to an embodiment of the present invention;

[0040] Figure 2 is a flow chart of a calculation method according to an embodiment of the present invention;

[0041] Figure 3 Schematic diagram of comparison between calculated values ​​and simulated values ​​of head difference according to the formula for different aquifer permeability ratios according to an embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram comparing the calculated value and the simulated value of the water head difference on both sides of the foundation pit water-stop curtain under four working conditions of an embodiment of the present invention. DETAILED DESCRIPTION

[0043] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0044] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0045] Embodiment 1

[0046] like Figure 2 As shown, this embodiment provides a method for calculating the water head difference on both sides of a foundation pit curtain taking into account the groundwater flow resistance effect, comprising the following steps:

[0047] Obtaining the factors affecting the water head difference on both sides of the foundation pit water-stop curtain and on both sides of the subway station, wherein the factors affecting the water head difference include the permeability coefficient ratio of the confined aquifer, the depth of the subway station, the distance between the subway station and the foundation pit, and the thickness of the confined aquifer;

[0048] Based on numerical simulation, the calculation formulas for the water head difference on both sides of the foundation pit water-stop curtain and the water head difference on both sides of the subway station are constructed respectively;

[0049] Based on various influencing factors of the water head difference, the water head difference calculation formulas on both sides of the foundation pit water-stop curtain and the water head difference calculation formulas on both sides of the subway station are modified in turn;

[0050] Based on the revised calculation formula for the water head difference on both sides of the foundation pit water-stop curtain and the revised calculation formula for the water head difference on both sides of the subway station, the distribution of the foundation pit pumping water level is obtained.

[0051] As an implementable approach, the specific process includes:

[0052] Theoretical analysis of head difference calculation:

[0053] Figure 1 The water level distribution curve of the confined aquifer under different working conditions is shown in Figure 2. It can be seen that under the water blocking effect of the water-stop curtain, a head difference is formed on both sides of the curtain, so the water level distribution curve inside and outside the pit becomes a two-stage type; when there is an adjacent subway station outside the pit, the water blocking effect of the station structure causes the water level between the station and the foundation pit to drop more, and the water level in the pit will further drop under constant flow pumping, so the head difference on both sides of the curtain changes (from Δh w becomes Δh w '), in addition, a new water head difference Δh will be formed on both sides of the station m , the groundwater level distribution caused by the dewatering of the confined aquifer will become a new three-stage distribution. In order to more easily calculate the confined water level inside and outside the pit, this embodiment proposes a simplified model for the dewatering of the confined aquifer in the foundation pit, and makes the following assumptions: (1) The two weakly permeable layers above and below the confined aquifer are regarded as impermeable upper and lower plates; (2) The groundwater behind the station only flows around from the bottom of the station into the pit; (3) The pit flows at a constant flow rate Q w To bring precipitation.

[0054] Assuming that the flow rate of groundwater behind the station flowing around the bottom of the station into the pit is Q1, without considering the groundwater recharge beside the station, the water head difference on both sides of the station can be calculated according to Darcy's infiltration law:

[0055]

[0056] Among them, A is the cross-sectional area between the confined aquifer and the bottom of the station through which groundwater flows, and K is the permeability coefficient of AqⅡ.

[0057] As for the water head difference on both sides of the foundation pit enclosure under the blocking effect of the subway station, since the station structure only blocks the groundwater seepage on one side of the enclosure, groundwater can be replenished into the pit from the other three sides, and the flow rate of groundwater flowing into the pit close to the station side cannot be quantified, and the seepage volume from the rear of the station to the front of the station cannot be measured in actual engineering. Therefore, this embodiment uses a numerical simulation method to solve the water head difference between the foundation pit enclosure and the two sides of the station.

[0058] Calculation parameter values:

[0059] In this embodiment, Visual Modflow software is used to establish a three-dimensional numerical model (a total of 273) considering the influence of different parameters. The specific parameter values ​​in the model can be seen in Table 1 below, where H w is the depth of the foundation pit water-stop curtain, b bd The ratio of the depth of the water-stop curtain inserted into the confined aquifer to the thickness of the aquifer (b bd =b b / b), J is the ratio of the horizontal permeability coefficient to the vertical permeability coefficient of the confined aquifer (J = K h / K v ), b is the thickness of the second confined aquifer, D is the distance between the subway station and the foundation pit, H is the depth of the subway station, where b bd , J, and b are the main factors affecting the water level distribution inside and outside the pit, and D and H are the main influencing parameters considering the barrier effect of the underground structure.

[0060] Table 1

[0061]

[0062] When selecting parameter values, this embodiment takes the following into consideration:

[0063] (1) Since the actual foundation pit project has a large area and a high groundwater level, the water level of the second confined aquifer needs to be lowered to prevent the pit bottom from rising and sudden damage. In order to obtain the stable drop value of the confined water level, the precipitation time in the model is set to 21 days;

[0064] (2) Since this embodiment only considers the water level distribution calculation caused by the precipitation of the confined aquifer under the suspended water-stop curtain, the insertion ratio of the foundation pit water-stop curtain varies between 0 and 1, and a total of 13 different insertion ratios are set; considering that the thickness of the underground aquifer in different sites will vary, the thickness variation range of the second confined aquifer is set to 13.5m-30m, and the soil layer of the aquifer is proportionally enlarged according to the soil thickness of the prototype foundation pit; when the distance between the subway station and the foundation pit is greater than 60m, the water blocking effect of the subway station is very small, and considering that a certain safety distance should be maintained between the newly built foundation pit and the existing operating subway station, the distance variation range between the subway station and the foundation pit is set to 10-60m;

[0065] (3) With reference to the relationship between the depth of the retaining structure and the excavation depth of the subway station in Tianjin, the buried depth of the station structure in the model is set to 15 m, and the thickness of the soil layer overlying the station is 3 m and the width is 20 m. Since only decompression and precipitation in the second confined aquifer are considered, the station structure can only form a barrier effect on the seepage of confined water by interrupting the continuous distribution of the thickness of the second confined aquifer. Therefore, the range of the station enclosure is set to 22-35.5 m.

[0066] Calculation of the pressure water head difference on both sides of the foundation pit water-stop curtain and on both sides of the station:

[0067] Water head difference on both sides of the foundation pit water-stop curtain:

[0068] According to the relationship between the water head difference on both sides of the foundation pit water-stop curtain and the insertion ratio of the water-stop curtain, it can be concluded that the water head difference on both sides of the foundation pit water-stop curtain increases with the increase of the insertion ratio of the water-stop curtain, and its change curve is three-stage. According to its three-stage change characteristics, fitting is performed separately to obtain the fitting formula of the water head difference under different water-stop curtain insertion ratios.

[0069] When 0<b bd When ≤0.18,

[0070]

[0071] When 0.18<b bd When ≤0.7,

[0072] Δh A1A2 =10b bd +1,

[0073] When 0.7<b bd When ≤1.0,

[0074]

[0075] Under the above basic conditions, by changing the vertical permeability coefficient (K v ) and the horizontal permeability coefficient (K h ) remains unchanged, taking into account the permeability ratio of the confined aquifer (J = K h / K v ) on the head difference on both sides of the water-stop curtain. As the ratio of the horizontal and vertical permeability coefficients of the aquifer increases, the head difference on both sides of the foundation pit water-stop curtain also increases. In order to correct the influence of the permeability ratio of the confined aquifer on the head difference on both sides of the water-stop curtain, based on the relationship between the permeability ratio of the confined aquifer and the head difference on both sides of the water-stop curtain, the first correction coefficient α1 of the foundation pit water-stop curtain is obtained based on J=5 as the basic working condition. By multiplying the head difference under other J by α1, the obtained head difference data all fall on the J=5 curve, that is, the head difference on both sides of the water-stop curtain is corrected. The value of the first correction coefficient α1 of the foundation pit water-stop curtain is:

[0076] α1=2.9J -0.6 ,

[0077] After correction by α1, the head difference expression on both sides of the water-stop curtain is:

[0078]

[0079] Based on the basic working conditions, the depth H of the subway station is changed to correct its influence on the water head difference on both sides of the water-stop curtain. The water head difference on both sides of the foundation pit water-stop curtain decreases with the increase of the depth of the subway station, but the overall change is small. The second correction coefficient α2 of the water-stop curtain is:

[0080] α2=0.85+0.005H,

[0081] After correction by α2, the head difference expression on both sides of the water-stop curtain is:

[0082]

[0083] Based on the basic working conditions, the distance D between the subway station and the foundation pit is changed to correct its influence on the water head difference on both sides of the water-stop curtain. The water head difference on both sides of the foundation pit water-stop curtain increases with the increase of the distance between the subway station and the foundation pit. The third correction coefficient α3 of the foundation pit water-stop curtain is:

[0084] α3=0.96+0.43e -D / 16.24 ,

[0085] After correction by α3, the head difference expression on both sides of the water-stop curtain is:

[0086]

[0087] Based on the basic working conditions, the thickness b of the subway station and the confined aquifer (AqⅡ) is changed to correct its influence on the water head difference on both sides of the water-stop curtain. The water head difference on both sides of the foundation pit water-stop curtain increases with the increase of the thickness of the confined aquifer. The fourth correction coefficient α4 of the foundation pit water-stop curtain is:

[0088] α4=0.59+3.1e -b / 6.6 ,

[0089] After correction by α4, the head difference expression on both sides of the water-stop curtain is:

[0090]

[0091] According to the formula, when pumping out the confined water in the foundation pit in the anisotropic aquifer under the barrier effect of the adjacent subway station, the water head difference on both sides of the foundation pit water-stop curtain is:

[0092] Δh A1A2(总) =Δh A1A2 / α1α2α3α4,

[0093] in,

[0094] α1α2α3α4=2.9J -0.6 (0.85+0.005H)(0.96+0.43e -D / 16.24)(0.59+3.1e -b / 6.6 ),

[0095]

[0096] Water head difference on both sides of the subway station:

[0097] The water head difference on both sides of the subway station decreases with the increase of the insertion ratio of the foundation pit water-stop curtain. The calculation formula of the water head difference on both sides of the subway station under different water-stop curtain insertion ratios is obtained by fitting.

[0098] Δh B1B2 =-0.4b bd +2.27.

[0099] Under the above basic conditions, by changing the vertical permeability coefficient (K v ) and the horizontal permeability coefficient (K h ) remains unchanged, taking into account the permeability ratio of the confined aquifer (J = K h / K v ) on the water head difference on both sides of the subway station. As the ratio of the horizontal to vertical permeability coefficient J of the aquifer increases, the water head difference on both sides of the foundation pit water-stop curtain also increases. The water head difference is corrected, and the first correction coefficient β1 of the subway station is taken as:

[0100] β1=A1+B1b bd ,

[0101] A1=1.45J -0.2 ,B1=-0.29+0.05J,

[0102] The head difference expression on both sides of the subway station after correction by β1 is:

[0103] Δh B1B2 '=Δh B1B2 / β1=(-0.4b bd +2.27) / (A1+B1b bd ).

[0104] The water head difference on both sides of the subway station increases with the increase of the depth of the subway station. The correction coefficient β2 of the subway station is:

[0105] β2=0.78+885×0.75 H ,

[0106] After β2 correction, the head difference expression on both sides of the water-stop curtain is:

[0107] Δh B1B2 ”=Δh B1B2 / β2=(-0.4b bd+2.27) / (0.78+885×0.75 H ).

[0108] The water head difference on both sides of the subway station decreases as the thickness of the confined aquifer increases. The third correction coefficient β3 of the subway station is:

[0109] β3=A2+B2b bd ,

[0110] A2=1.5-0.01b, B2=-1.35+0.09b,

[0111] The head difference expression on both sides of the subway station after correction by β3 is:

[0112] Δh B1B2 ”'=Δh B1B2 / β3=(-0.4b bd +2.27) / (A2+B2b bd ).

[0113] As the distance between the subway station and the foundation pit gradually increases, the water head difference on both sides of the subway station shows a trend of gradually decreasing, then increasing, and finally decreasing. The fourth correction coefficient β4 of the subway station is:

[0114] β4=A3+B3b bd ,

[0115] A3=0.81+0.16sin(π(D-18.33) / 16.67), B3=-0.18+1.12×0.96 D ,

[0116] The water head difference expression on both sides of the subway station after correction by β4 is:

[0117] Δh B1B2 ””=Δh B1B2 / β4=(-0.4b bd +2.27) / (A3+B3b bd ).

[0118] According to the formula, when considering the pumping of confined water in the foundation pit in the anisotropic aquifer under the barrier effect of the adjacent subway station, the water head difference on both sides of the subway station is:

[0119] Δh B1B2(总) =Δh B1B2 / β1β2β3β4,

[0120] in,

[0121] Δh B1B2 =-0.4b bd +2.27,

[0122] β1β2β3β4=(A1+B1b bd )(0.78+885×0.75 H )(A2+B2b bd )(A3+B3b bd ),

[0123]

[0124] Comparison of calculated and simulated values:

[0125] Figure 3 The calculated value of the water head difference under different aquifer permeability ratios is compared with the simulated value. It can be seen that the calculated value of the water head difference between the foundation pit water-stop curtain and the two sides of the subway station is highly consistent with the numerical simulation value, indicating that the two formulas are highly credible.

[0126] In order to further verify the applicability of the formula under different working conditions, four new working conditions are selected for modeling. The corresponding parameter values ​​of the four working conditions are shown in Table 2. Figure 4 The calculated and simulated values ​​of the water head difference on both sides of the foundation pit water-stop curtain under four working conditions are shown. It can be seen that the two are basically consistent under four different working conditions, indicating that the calculation formula proposed in this embodiment is relatively accurate, but the formula still needs further verification in actual engineering.

[0127] Table 2

[0128]

[0129] Calculation of pumping water level distribution in confined aquifer under the barrier effect of underground structures:

[0130] The analytical formula for the distribution of pressure water levels inside and outside the pit when pumping at a constant flow rate is:

[0131]

[0132] Among them, Q w is the water inflow in the pit, b is the thickness of the confined aquifer, and b b is the depth of the foundation pit enclosure embedded in the aquifer, K is the comprehensive permeability coefficient of the confined aquifer, x w is the radius of the pumping well, x0 is the distance from the pumping well to the inside of the enclosure, x0' is the distance from the pumping well to the outside of the enclosure, and X is the impact radius.

[0133] When calculating the pressure water level under the combined water blocking effect of the adjacent subway station and the foundation pit water-stop curtain, the head difference obtained in this embodiment should be added for further correction.

[0134] This embodiment first conducts a preliminary analysis on the influencing factors of the head difference on both sides of the foundation pit enclosure and on both sides of the station under the barrier effect of the subway station, and then establishes a three-dimensional numerical model of foundation pit dewatering considering the barrier effect of the subway station. Further, a series of three-dimensional finite difference models considering different water-stop curtain insertion ratios, aquifer anisotropy, aquifer thickness, distance between the subway station and the foundation pit, and depth of the subway station are established. By analyzing the changing law of the head difference under different parameters, the relationship between related parameters is established, and a calculation formula for the head difference on both sides of the foundation pit enclosure and on both sides of the existing station is given, and the effectiveness is verified by establishing a new numerical model.

[0135] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for calculating the water head difference on both sides of a foundation pit curtain considering the groundwater flow resistance effect, characterized in that: The following steps are involved: Obtaining the factors affecting the water head difference on both sides of the foundation pit water-stop curtain and on both sides of the subway station, wherein the factors affecting the water head difference include the permeability coefficient ratio of the confined aquifer, the depth of the subway station, the distance between the subway station and the foundation pit, and the thickness of the confined aquifer; Based on numerical simulation, the calculation formulas for the water head difference on both sides of the foundation pit water-stop curtain and the water head difference on both sides of the subway station are constructed respectively; Based on various influencing factors of the water head difference, the water head difference calculation formulas on both sides of the foundation pit water-stop curtain and the water head difference calculation formulas on both sides of the subway station are modified in turn; Based on the revised calculation formula for the water head difference on both sides of the foundation pit water-stop curtain and the revised calculation formula for the water head difference on both sides of the subway station, the corresponding water head difference on both sides of the foundation pit water-stop curtain and the water head difference on both sides of the subway station are obtained.

2. The method according to claim 1, characterized in that Factors affecting the water head difference on both sides of the foundation pit water-stop curtain and on both sides of the subway station also include the ratio of the depth of the water-stop curtain inserted into the confined aquifer to the thickness of the aquifer.

3. The method according to claim 2, characterized in that The process of modifying the head difference calculation formula on both sides of the foundation pit water-stop curtain in turn based on various influencing factors of the head difference includes: The first correction coefficient of the foundation pit water-stop curtain is obtained based on the permeability coefficient ratio of the confined aquifer, the second correction coefficient of the foundation pit water-stop curtain is obtained based on the depth of the subway station, the third correction coefficient of the foundation pit water-stop curtain is obtained based on the distance between the subway station and the foundation pit, and the fourth correction coefficient of the foundation pit water-stop curtain is obtained based on the thickness of the confined aquifer; based on the first correction coefficient, the second correction coefficient, the third correction coefficient and the fourth correction coefficient of the foundation pit water-stop curtain, the calculation formula for the water head difference on both sides of the foundation pit water-stop curtain is corrected.

4. The method according to claim 3, characterized in that The corrected calculation formula for the head difference on both sides of the foundation pit water-stop curtain is as follows: Dh A1A2(总) =Δh A1A2 / α1α2α3α4, in, α1α2α3α4=2.9J -0.6 (0.85+0.005H)(0.96+0.43e -D / 16.24 )(0.59+3.1e -b / 6.6 ), Wherein, J is the permeability ratio of the confined aquifer, α1 is the first correction coefficient of the foundation pit water-stop curtain, H is the depth of the subway station, α2 is the second correction coefficient of the foundation pit water-stop curtain, D is the distance between the subway station and the foundation pit, α3 is the third correction coefficient of the foundation pit water-stop curtain, b is the thickness of the confined aquifer, α4 is the fourth correction coefficient of the foundation pit water-stop curtain, and b bd It is the ratio of the depth of the water-stop curtain inserted into the confined aquifer to the thickness of the aquifer.

5. The method according to claim 2, characterized in that: The process of sequentially correcting the water head difference calculation formula on both sides of the subway station based on various influencing factors of the water head difference includes: A first correction coefficient of the subway station is obtained based on the permeability coefficient ratio of the confined aquifer, a second correction coefficient of the subway station is obtained based on the depth of the subway station, a third correction coefficient of the subway station is obtained based on the thickness of the confined aquifer, and a fourth correction coefficient of the subway station is obtained based on the distance between the subway station and the foundation pit; based on the first correction coefficient, the second correction coefficient, the third correction coefficient and the fourth correction coefficient of the subway station, the head difference calculation formula on both sides of the subway station is corrected.

6. The method according to claim 5, characterized in that The revised calculation formula for the water head difference on both sides of the subway station is as follows: Dh B1B2(总) =Δh B1B2 / β1β2β3β4, in, Δh B1B2 =-0.4b bd +2.27, <h2 style=";text-align:left;direction:ltr">β1β2β3β4=(A1+B1b<h2 style=";text-align:left;direction:ltr"> bd <h2 style=";text-align:left;direction:ltr"> )(0.78+885×0.75<h2 style=";text-align:left;direction:ltr"> H <h2 style=";text-align:left;direction:ltr"> A2+B2b)<h2 style=";text-align:left;direction:ltr"> bd <h2 style=";text-align:left;direction:ltr"> (A3+B3b)<h2 style=";text-align:left;direction:ltr"> bd <h2 style=";text-align:left;direction:ltr"> ), Wherein, J is the permeability ratio of the confined aquifer, β1 is the first correction coefficient of the subway station, H is the depth of the subway station, β2 is the second correction coefficient of the subway station, D is the distance between the subway station and the foundation pit, β3 is the third correction coefficient of the subway station, b is the thickness of the confined aquifer, β4 is the fourth correction coefficient of the subway station, and b bd It is the ratio of the depth of the water-stop curtain inserted into the confined aquifer to the thickness of the aquifer.

7. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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