A prediction method for ground surface deformation caused by a shield tunnel passing under an existing diaphragm wall

Abstract

The present invention discloses a method for predicting surface deformation caused by a shield tunnel passing under an existing diaphragm wall, belonging to the field of shield construction of urban subway tunnels, including: calculating the shield jacking thrust according to soil layer parameters and shield parameters, and calculating the jacking pressure based on the shield jacking thrust; calculating Fourier coefficients based on the deflection caused by the jacking pressure acting on the diaphragm wall; obtaining the deformation amount of the diaphragm wall based on the Fourier coefficients and the geometric and mechanical parameters of the tunnel and the diaphragm wall, and determining the proportional coefficient according to the mechanical properties of the rock and soil layers; calculating the ground heave volume based on the deformation amount of the diaphragm wall and the proportional coefficient; calculating the maximum value of the ground heave based on the ground heave volume; and calculating the deformation of any point on the ground based on the maximum value of the ground heave. The present invention can obtain a semi-analytical solution of the ground heave deformation at any position.

Description

Technical Field

[0001] The invention belongs to the field of shield construction of urban subway tunnels, and particularly relates to a method for predicting surface deformation caused by a shield tunnel passing under an existing diaphragm wall. Background Art

[0002] During the shield construction of urban subway tunnels, the original stress state of the surrounding strata will be disturbed, which may lead to the cracking, tilting or even collapse of existing buildings. Therefore, during the shield construction process, it is necessary to strictly control and monitor the ground settlement to avoid damage to surrounding buildings. This requires engineers to use professional knowledge to estimate the potential ground settlement and evaluate the possibility of serious damage to surrounding buildings.

[0003] Early studies mainly used the basic principles of elastic mechanics and soil mechanics to establish analytical solutions for ground settlement at the boundary of simple tunnel excavations. Later, many scholars at home and abroad continuously proposed general solutions and analytical solutions for ground deformation caused by tunnel excavations, as well as empirical solutions to expand the application conditions of the analytical solutions. In addition, the imbalance of the stratum-tunnel structure caused by a shield tunnel passing under an existing tunnel is another common and important problem. And how to predict the deformation of the retaining structure and ground heave caused by a shield tunnel passing through the retaining structure is still a difficult problem to be solved. Summary of the Invention

[0004] To solve the above technical problems, the invention provides a method for predicting surface deformation caused by a shield tunnel passing under an existing diaphragm wall, including:

[0005] Calculating the shield thrust according to soil layer parameters and shield parameters, and calculating the jacking pressure based on the shield thrust;

[0006] Calculating Fourier coefficients based on the deflection caused by the jacking pressure acting on the diaphragm wall;

[0007] Obtaining the deformation amount of the diaphragm wall based on the Fourier coefficients and the geometric and mechanical parameters of the tunnel and the diaphragm wall, and determining the proportionality coefficient according to the mechanical properties of the rock and soil layers;

[0008] Calculating the ground heave volume based on the deformation amount of the diaphragm wall and the proportionality coefficient;

[0009] Calculating the maximum value of the ground heave based on the ground heave volume;

[0010] Calculating the deformation of any point on the ground based on the maximum value of the ground heave.

[0011] Preferably, the calculation expression for calculating the shield thrust according to soil layer parameters and shield parameters is:

[0012] ;

[0013] Among them, F f is the frictional force between the shield machine shell and the soil mass, and F T is the mud pressure on the working face, and F G is the penetration resistance received by the cutter head.

[0014] Preferably, the calculation expression of the frictional force between the shield machine shell and the soil mass is:

[0015] ;

[0016] Among them, μ1 is the friction coefficient, N1 and N2 are the left - right and up - down normal earth pressures acting on the unit soil mass of the shield shell respectively, and L is the length of the shield;

[0017] The calculation expression of the mud pressure on the working face is:

[0018] ;

[0019] Among them, D is the radius, ν1 is the Poisson's ratio of the soil, q e is the pressure value on the inner wall of the soil bin, a is the length of the soil bin, is the Poisson's ratio of the soil, φ is the internal friction angle of the soil, and ω is the cutter head opening ratio;

[0020] The calculation expression of the penetration resistance received by the cutter head is:

[0021] ;

[0022] Among them, α and z1, z2, and z3 are undetermined coefficients, and τ p is the shear strength of the shield soil mass.

[0023] Preferably, the calculation expression of the deformation amount of the diaphragm wall obtained based on the Fourier coefficients and the geometric and mechanical parameters of the tunnel and the diaphragm wall is:

[0024] ;

[0025] Among them, V W is the deformation amount of the diaphragm wall, A mn is the Fourier coefficient, H is the depth of the diaphragm wall, m and n are the series numbers, and L0 is the width of the diaphragm wall.

[0026] Preferably, the calculation expression of the ground heave volume calculated based on the deformation amount of the diaphragm wall and the proportionality coefficient is:

[0027] ;

[0028] Among them, Mu is the proportionality coefficient, and V S is the ground heave volume.

[0029] Preferably, the calculation expression for calculating the maximum value of ground heave based on the ground heave volume is:

[0030] ;

[0031] where S max is the maximum deformation, x is the lateral displacement, x m is the distance from the position of the maximum deformation, x0 is the lateral deformation influence range, y is the vertical displacement, and y0 is the vertical deformation influence range.

[0032] Preferably, the calculation expression for calculating the deformation of any point on the ground based on the maximum value of the ground heave is:

[0033] ;

[0034] where S is the deformation of any point on the ground.

[0035] On the other hand, the present invention also provides an electronic device, including a memory, a processor, and a calculation program stored in the memory and executable on the processor. When the processor executes the computer program, the prediction method for surface deformation caused by a shield tunnel passing under an existing diaphragm wall is implemented.

[0036] On the other hand, the present invention also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the prediction method for surface deformation caused by a shield tunnel passing under an existing diaphragm wall is implemented.

[0037] Compared with the prior art, the present invention has the following advantages and technical effects:

[0038] The present invention discloses a prediction method for surface deformation caused by a shield tunnel passing under an existing diaphragm wall, belonging to the field of shield construction of urban subway tunnels, including: calculating the shield thrust based on soil layer parameters and shield parameters, and calculating the jacking pressure based on the shield thrust; calculating Fourier coefficients based on the deflection caused by the jacking pressure acting on the diaphragm wall; obtaining the deformation amount of the diaphragm wall based on the Fourier coefficients and the geometric and mechanical parameters of the tunnel and the diaphragm wall, and determining the proportionality coefficient according to the mechanical properties of the rock and soil layer; calculating the ground heave volume based on the deformation amount of the diaphragm wall and the proportionality coefficient; calculating the maximum value of the ground heave based on the ground heave volume; calculating the deformation of any point on the ground based on the maximum value of the ground heave. The present invention can obtain a semi-analytical solution of the ground heave deformation at any position; at the same time, the prediction method is simple and has clear physical meaning; and the calculation principle is simple, easy to program, and has a fast calculation speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings, which form a part of this application, are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation of this application. In the accompanying drawings:

[0040] Figure 1 It is a schematic diagram of the calculation model for ground heave caused by the deformation of the diaphragm wall in the embodiment of the present invention;

[0041] Figure 2 It is a schematic diagram of the lateral and longitudinal deformation curves in the embodiment of the present invention.

[0042] Figure 3 It is a flowchart of the method for predicting surface deformation caused by a shield tunnel passing under an existing diaphragm wall in the embodiment of the present invention. Detailed implementation manners

[0043] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the accompanying drawings and combine with the embodiments to detail this application.

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

[0045] Embodiment 1

[0046] In this embodiment, a method for predicting surface deformation caused by a shield tunnel passing under an existing diaphragm wall is provided, including:

[0047] Calculating the shield thrust based on the soil layer parameters and shield parameters, and calculating the jacking pressure based on the shield thrust;

[0048] Calculating the Fourier coefficients based on the deflection caused by the jacking pressure acting on the diaphragm wall;

[0049] Obtaining the deformation amount of the diaphragm wall based on the Fourier coefficients and the geometric and mechanical parameters of the tunnel and the diaphragm wall, and determining the proportionality coefficient according to the mechanical properties of the rock and soil layers;

[0050] Calculating the ground heave volume based on the deformation amount of the diaphragm wall and the proportionality coefficient;

[0051] Calculating the maximum value of the ground heave based on the ground heave volume;

[0052] Calculating the deformation of any point on the ground based on the maximum value of the ground heave.

[0053] Basic assumptions:

[0054] (1) The diaphragm wall does not undergo plastic failure during the shield tunneling process. Therefore, it is assumed to be a linear elastic material, and the seepage effect of groundwater is not considered.

[0055] (2) During the tunneling process, the volume of the soil behind the diaphragm wall remains constant.

[0056] (3) The lateral deformation of the diaphragm wall causes ground heave.

[0057] (4) The deformation of the diaphragm wall V W is proportional to the deformation V S . The specific equation is shown in Equation (1):

[0058] (1)

[0059] where Mu is the proportionality coefficient, which depends on the compressibility of the soil layer. The value of Mu can be set to 0.8.

[0060] (5) To simplify the calculation, the weighted average method is used to homogenize the multi-layer soil.

[0061] (6) The diaphragm wall follows the Kirchhoff plate theory. The reason is that the ratio of the wall width to the depth is 1.2m / 41m, which is much less than 1 / 5. Therefore, this diaphragm wall is a typical Kirchhoff surface.

[0062] (7) Due to the high strength of the diaphragm wall, only elastic deformation of the wall is considered. In addition, the diaphragm wall is considered an isotropic material.

[0063] The prediction model of ground surface deformation caused by subway shield tunneling considering three-dimensional effects establishes the relationship between the deformation of the retaining structure and the ground deformation, and further obtains the solution of foundation heave considering three-dimensional space effects. The calculation model of ground heave caused by the deformation of the diaphragm wall is as Figure 1 shown, where V W represents the deformation of the retaining structure, and V S represents the ground surface deformation.

[0064] The deformation of the diaphragm wall retaining structure is caused by the additional thrust of the shield, which can be simplified as a bending problem of a rectangular thin plate simply supported on four sides.

[0065] In the Kirchhoff plate theory, the deflection w0 caused by the shield pushing pressure P acting on the diaphragm wall is a double Fourier series.

[0066] (2)

[0067] In the formula, A mn is the Fourier coefficient. m and n are positive integers. The specific value of A mn can be calculated through the boundary conditions.

[0068] For any uniformly distributed load q, the value of A in Equation (2) mn is:

[0069] (3)

[0070] where D1 is the flexural rigidity of the thin plate, and the expression is:

[0071] (4)

[0072] where E is the elastic modulus of the plate and μ is the Poisson's ratio of the plate. Under the given conditions, the two "tunnel" regions (Ω1 and Ω2) on the thin plate are sufficient to generate an additional thrust p. In local coordinates, the positions of the two circles are and , and the radius is R. Therefore, A mn can be written as:

[0073] (5)

[0074] Since there is no force acting on the Ω3 region, Equation (5) can be simplified to:

[0075] (6)

[0076] Using the polar coordinate transformation (r, θ) to solve the double integral, substitute , and dA = rdrdθ into Equation (6). Equation (6) becomes

[0077] (7)

[0078] Equation (7) has no elementary solution. The MATLAB commercial software provides a double numerical integration function dblquad. The value of Amn can be calculated using MATLAB code.

[0079] According to Equation (1), the deformation volume V of the wall can be further calculated W ,

[0080] (8)

[0081] Expanding Equation (3), the expression of V W can be obtained:

[0082] (9)

[0083] As Figure 2As shown in the figure, considering the spatial effect of ground deformation, when calculating the deformation volume, the transverse deformation curve perpendicular to the diaphragm wall (x-direction) and the longitudinal deformation curve parallel to the diaphragm wall (y-direction) should be introduced. A large number of experimental and numerical results show that the transverse deformation curve fits well with the normal distribution. Therefore, the expression of the transverse deformation curve is:

[0084] (10)

[0085] In the formula, S xmax is the maximum transverse deformation, x0 is the transverse deformation influence range, and x m is the distance from the position of the maximum deformation value. Peck (1969) and Bowles (1988) proposed an empirical expression to determine the value of x0 of ground deformation,

[0086] (11)

[0087] In the formula, φ is the internal friction angle of the soil, and x m can be calculated by the empirical expression,

[0088] (12)

[0089] Based on a large number of measured ground deformation data in Beijing, China, the longitudinal deformation curve can be well fitted by the Boltzmann function. Therefore, the ground longitudinal deformation can be expressed as:

[0090] (13)

[0091] In the formula, S ymax is the maximum longitudinal deformation, and y0 is the longitudinal deformation influence range. Referring to the calculation method of x0, the value of y0 can be determined as:

[0092] (14)

[0093] In the formula, L0 is the width of the diaphragm wall. Considering the transverse deformation and longitudinal deformation, the deformation S at any point on the ground is:

[0094] (15)

[0095] In the formula, S max is the maximum deformation. Within the deformation influence range, the deformation volume V S ,

[0096] (16)

[0097] Equation (16) does not have the form of an elementary function, but it can be solved using the double numerical integration function dblquad in Matlab code.

[0098] The ground heave caused by the tunnel passing through the diaphragm wall is mainly due to the shield thrust force F. The jacking force and the driving resistance of an earth pressure balance shield are equal. The driving resistance of the shield includes: the frictional force F between the outer shell of the shield machine and the soil f , the mud pressure F on the working face T , the penetration resistance F received by the cutting edge G , the frictional force F between the segments and the shell plate at the tail of the shield P and the traction force F at the tail of the shield Y . The main resistances of the shield are F f , F T and F G . Therefore, the shield jacking force F can be approximated as,

[0099] (17)

[0100] (1) The frictional force F between the outer shell of the shield machine and the soil f

[0101] Calculate the frictional force F between the shield and the soil f Before calculating the frictional force F between the shield and the soil, it is necessary to calculate the upper soil pressure p and the left and right pressures q during the driving process. Assume that the soil on both sides of the excavation undergoes active deformation after being disturbed and extends upward to the ground, forming a soil arch ring with a diameter of 2D. Terzaghi derived the expression for the upper soil pressure p e1 expression,

[0102] (18)

[0103] In the formula, K is the lateral earth pressure coefficient, μ0 is the pipe-soil friction coefficient, H is the height of the diaphragm wall, and γ0 is the average unit weight of the soil.

[0104] The soil pressure p at the bottom of the shield e2 is mainly due to the soil resistance caused by the self-weight of the shield,

[0105] (19)

[0106] In the formula, W is the self-weight of the shield, and L is the length of the shield.

[0107] The horizontal soil pressures on the left and right sides of the shield are,

[0108] (20)

[0109] Therefore, the frictional force F between the shield and the soil f is,

[0110] (21)

[0111] Wherein, N1 and N2 are respectively the left - right and up - down normal earth pressures acting on the unit soil mass of the shield shell, and μ1 is the friction coefficient, which is taken as . Therefore, by integrating the circular shield tunnel, N1 and N2 are respectively obtained as

[0112] (22)

[0113] (23)

[0114] F T includes the frictional resistance F between the inner wall of the soil bin and the soil T1 and the resistance F in front of the excavation face T2 . In order to analyze the frictional resistance, the following assumptions need to be proposed: ① The inner wall of the soil bin does not deform, the soil mass is an ideal elastic body and the gravity influence is ignored; ② The contact between the soil bin and the surrounding soil mass is flat and the force distribution is uniform. Based on the above assumptions, the force equilibrium equation of the micro - element body is established

[0115] (24)

[0116] After simplification, it is[[ID=3I]]

[0117] (25)

[0118] Considering , Equation (25) becomes

[0119] (26)

[0120] In addition, the stress and strain of the micro - element body satisfy Hook's law

[0121] (27)

[0122] Wherein, E1 and ν1 are respectively the elastic modulus and Poisson's ratio of the soil. Considering that the inner wall of the soil bin is rigid, so ε θ = ε r = 0, it can be obtained that

[0123] (28)

[0124] By combining Equation (26) and (28), the solution of the differential equation can be obtained

[0125] (29)

[0126] Wherein, C is an arbitrary constant. When l = a, at the junction of the soil bin and the pressure baffle, the pressure value σ1 of the inner wall of the soil bin is qe , substituting into Equation (29), we get:

[0127] (30)

[0128] Further combining Equations (26), (29) and (30), the normal stress and shear stress on the soil bin wall surface are obtained as follows,

[0129] (31)

[0130] (32)

[0131] From this, the frictional resistance F between the soil bin and the soil can be obtained T1 ,

[0132] (33)

[0133] The resistance F directly in front of the shield excavation face T2 Calculated according to the static earth pressure state, that is:

[0134] (34)

[0135] Where ω is the cutter head opening ratio. Therefore, the shield excavation face resistance F T is

[0136] (35)

[0137] (3) The cutter head is subject to the penetration resistance F G

[0138] F G mainly represents the penetration degree of the cutter head.

[0139] (36)

[0140] Where α, z1, z2, and z3 are undetermined coefficients, and τ p is the shear strength of the shield soil mass. Using the method of dimensional analysis, z1 = z2 = z3 = 1 is obtained. And it is considered that α = 0.0607 in the fine sand layer.

[0141] Combining Equations (17), (21), (35) and (36), it can be seen that the shield jacking force F is mainly affected by the excavation area, soil bin pressure and cutter head opening ratio. F is positively correlated with the excavation area and soil bin pressure, and negatively correlated with the cutter head opening ratio.

[0142] Such as Figure 3As shown, first, according to the soil layer parameters and shield parameters, calculate the shield jacking force F and jacking pressure P according to equations (17), (21), (35) and (36). Then, substitute the geometric and mechanical parameters of the tunnel and diaphragm wall into equation (9) to obtain the deformation V of the diaphragm wall. W Determine the proportionality coefficient M in equation (1) according to the mechanical properties of the soil. u Then, use equation (1) to calculate the ground heave volume V. S According to the value of V, S use the Matlab code to obtain the numerical solution of equation (16) and calculate the maximum value S of the ground heave. max Finally, the ground heave S at any point can be calculated by equation (15). The main calculation parameters in the surface deformation process are the excavation area of the shield, the soil chamber pressure and the cutter head opening rate, the Poisson's ratio ν1 and friction angle φ of the soil, the elastic modulus E and Poisson's ratio μ of the diaphragm wall, the depth H and thickness b of the diaphragm wall, and the proportionality coefficient Mu. Among these parameters, the value of Mu needs to be determined according to the properties of the rock and soil layers.

[0143] Example 2

[0144] According to the proposed deformation calculation method, determine the deformation of the diaphragm wall. The mechanical parameters of the diaphragm wall used in the calculation are shown in Table 2, and other formation parameters are shown in Table 1. The diaphragm wall is constructed with C30 concrete. The values of m and n in equation (4) affect the calculation accuracy of the method in this paper. In order to determine the optimal values of m and n, more than 100 experimental calculations were carried out. In the experimental calculations, the values of m and n varied between 3 and 20. When m and n are greater than 10, the calculation results change little. The results show that the calculation results have the best accuracy when the values of m and n are 11.

[0145] Table 1

[0146] Soil layer <![CDATA[重度γ(kN / m 3 )]]> <![CDATA[Bearing capacity f ak (kPa)]]> Internal friction angle φ (°) Compression modulus Es (MPa) Poisson's ratio μ Permeability coefficient k (cm / s) Miscellaneous fill ①-1 20.0 - 6.5 - 0.3 5.0e-3 Silty clay ③-1 14.1 123 9.7 4.6 0.3 3.5e-7 Silty clay ③-2 13.3 155 7.8 3.4 0.3 2.8e-7 Silty clay with sand ③-5 13.5 125 8.6 4.3 0.25 6.4e-5 Fine sand ④-1 19.0 256 28 18.6 0.25 3.1e-3 Fine sand ④-2 19.5 300 36 22.6 0.25 2.1e-3

[0147] Table 2

[0148] Material Elastic modulus E (GPa) Poisson's ratio Μ Internal friction angle φ (°) Diaphragm wall 20 0.1 50

[0149] Select the deformation monitoring points DB-1, DB-2, DB-3, DB-4, DB-5 and the horizontal deformation monitoring point CX-1 in the monitoring section A-A' to verify the accuracy of the proposed method for the deformation when passing through the diaphragm wall. The calculated value of the horizontal deformation at the top of the diaphragm wall is 0.6 mm, which is not much different from the measured value. The calculated deformation values of DB-1, DB-2, DB-3, DB-4, DB-5 are 5.0 mm, 5.95 mm, 7.44 mm, 7.64 mm, 7.9 mm respectively. Except for the monitoring point DB-1, the maximum difference between the measured deformation and the calculated deformation is 24.6%. In addition, the measured ground heave value is less than the calculated value, and the predicted maximum surface heave deformation is 8.5 mm; the maximum horizontal displacement of the diaphragm wall is 13.5 mm. The reason is that the vertical deformation of the diaphragm wall is not considered in the model. In fact, the deformation of the wall will affect the ground heave around. However, the measured deformation of the diaphragm wall is 0.2 mm. This shows that the deformation of the diaphragm wall is small and will not significantly affect the predicted surface deformation ability of the model. Therefore, the results show that this method can be used for the ground heave deformation caused by the shield tunnel passing through the building enclosure structure.

[0150] According to the foundation heave calculation results, the trench shape was observed during the entire ground heave process. The maximum deformation is 7.64 mm, which is located at the exact center of the two tunnels. The farther away from the tunnel, the smaller the deformation value.

[0151] Numerical simulation verification of a subway passing under the diaphragm wall

[0152] Due to problems such as few data points, low measurement accuracy, and strong interference from the surrounding environment in the on-site measured data, the subway monitoring data cannot fully reflect the deformation evolution law of Yuanlin Road caused by the passing of Line 12, and the internal deformation and stress characteristics of the rock and soil mass cannot be intuitively displayed. Therefore, numerical simulation means were used to carry out the analysis of the influence of the subway passing.

[0153] (1) Establishment of numerical model

[0154] Considering reducing the influence of boundary constraints on excavation, the calculation range of the model established this time is 20 m on each side in the y direction and 80 m on each side in the x direction, and 83 m below the ground surface is taken above the top surface. The overall model size is 193 m × 50 m × 83 m. The strata are simplified into 6 kinds of strata, including ①-1 miscellaneous fill, ③-1 silty clay, ③-2 silty clay, ④-1 fine sand, ④-2 fine sand. At the same time, in order to accurately simulate the influence of shield tunnel excavation on the deformation of Yuanlin Road Station and the ground surface, the shield tunnel section and the frame structure of Yuanlin Road Station were subjected to grid encryption treatment, and the average grid size in this area is 0.5 m. The grid cells of the entire model are 175,515, and the number of nodes is 187,740. The boundary constraints are that the x and y boundaries adopt normal simply supported boundaries, and the bottom layer is the x, y, and z fixed boundaries.

[0155] (2)Calculation parameters

[0156] To fully study the interaction between various structural components and the soil during the shield tunneling process, solid elements are used for the soil, tunnel, and frame structure. Among them, the hardening soil HS elastoplastic constitutive model is used for the soil, and the linear elastic model is used for the shield segments and frame structure. The material parameters are shown in Table 3.

[0157] Table 3

[0158] Material name <![CDATA[Heavy kN / m 3 > Cohesion (KPa) Friction angle (°) Elastic modulus (MPa) Poisson's ratio Miscellaneous fill ①-1 20.0 10 6.5 3.0 0.3 Silty clay ③-1 14.1 16.5 9.7 5.0 0.3 Silty clay ③-2 13.3 13.1 7.8 5.2 0.3 Silty clay with sand ③-2 13.5 11 8.6 5.1 0.25 Fine sand ④-1 19.0 0 28 13.8 0.25 Fine sand ④-2 19.5 0 36 15.8 0.25 Frame structure of Yuanlin Road Station 2800 \ \ 80000 0.15 Shield segment 2500 \ \ 50000 0.2

[0159] (3)Calculation steps

[0160] This numerical calculation is divided into three stages. First, the in-situ stress is balanced; then the excavation and segment installation processes are simulated. Finally, when approaching the diaphragm wall, the propulsion load of the shield tunnel is applied. The influence of shield tunneling on the diaphragm wall, Yuanlin Road Station of Line 4, and ground surface deformation is simulated.

[0161] (4)Comparison between the simulation results and the newly proposed model

[0162] According to the numerical calculation results, the deformation of the diaphragm wall and the ground surface displacement results obtained from the numerical simulation are compared and analyzed with the results calculated by the newly proposed model. Generally, the overall trends of the horizontal displacement of the diaphragm wall and the ground surface deformation obtained from the numerical simulation are consistent. During the shield jacking process, a parabolic displacement distribution of "large in the middle and small at both ends" along the wall direction occurs in the diaphragm wall. And within a certain range, the farther away from the diaphragm wall, the greater the ground surface heave deformation. When reaching a certain range, the ground surface deformation decreases rapidly. By comparing the numerical values of the numerical simulation and the new model calculation, it can be found that the maximum errors of the horizontal displacement of the diaphragm wall and the ground surface deformation are 15% and 13% respectively. The greater the depth of the diaphragm wall, the greater the deviation between the two. When the ground surface vertical deformation is far from the wall, the deviation gradually increases. And after reaching a certain range, the error between the two decreases. At the same time, the ground surface deformation calculated by the new model is slightly larger than the numerical simulation result. The reason is that the ground surface settlement deformation caused by shield excavation is considered in the numerical simulation, offsetting part of the heave deformation caused by shield jacking.

[0163] To further reveal the mechanism of ground surface deformation caused by shield pushing, compared with the situation under shield pushing, after shield excavation is completed, the horizontal deformation of the diaphragm wall is relatively small, with a deformation value of 6.0 mm. However, the stress distributions of the diaphragm wall under shield pushing and after shield excavation are approximately the same, and stress concentration occurs at the bottom plate position. The maximum stresses of the diaphragm wall under shield pushing and after shield excavation are 24.8 MPa and 25.2 MPa respectively. The relatively small horizontal deformation of the diaphragm wall after shield excavation indicates that the diaphragm wall plays a good "partitioning" role, reducing the settlement of the protected subway frame structure and the ground surface. However, under the action of shield pushing, the horizontal deformation of the diaphragm wall causes a relatively large uplift deformation of the subway frame structure and the ground surface. The maximum uplift deformation is 8.0 mm. At the same time, settlement deformation occurs in the subway frame structure far from the shield section, indicating that the frame structure has a certain degree of tilting deformation. If this tilting deformation is large, it is likely to cause cracking and damage to the frame structure. Therefore, as a retaining structure, the diaphragm wall can better protect the safety of existing structures caused by shield tunnel excavation, but it may cause a relatively large ground surface uplift deformation under the action of shield pushing.

[0164] On the other hand, the present invention also provides an electronic device, including a memory, a processor, and a computing program stored in the memory and executable on the processor. When the processor executes the computer program, the method for predicting ground surface deformation caused by a shield tunnel passing under an existing diaphragm wall is implemented.

[0165] On the other hand, the present invention also provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the method for predicting ground surface deformation caused by a shield tunnel passing under an existing diaphragm wall is implemented.

[0166] The above is only a preferred specific embodiment 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 those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A prediction method for surface deformation caused by a shield tunnel passing under an existing diaphragm wall, characterized in that, Including: Calculating the shield jacking force according to the soil layer parameters and shield parameters, and calculating the jacking pressure based on the shield jacking force; Calculating the Fourier coefficients based on the deflection caused by the jacking pressure acting on the diaphragm wall; Obtaining the deformation of the diaphragm wall based on the Fourier coefficients and the geometric and mechanical parameters of the tunnel and the diaphragm wall, and determining the proportionality coefficient according to the mechanical properties of the rock and soil layers; Calculating the ground heave volume based on the deformation of the diaphragm wall and the proportionality coefficient; Calculating the maximum value of the ground heave based on the ground heave volume; Calculating the deformation of any point on the ground based on the maximum value of the ground heave; The expression for calculating the Fourier coefficients based on the deflection caused by the jacking pressure acting on the diaphragm wall is: ； Among them, is the Fourier coefficient, is the diaphragm wall width, is the diaphragm wall height, is an arbitrary uniformly distributed load, and m and n are positive integers, is the flexural rigidity of the thin plate; The calculation expression for obtaining the deformation of the diaphragm wall based on the Fourier coefficients and the geometric and mechanical parameters of the tunnel and the diaphragm wall is: ； Among them, V W is the deformation of the diaphragm wall, H is the depth of the diaphragm wall, m and n are series numbers, and L0 is the width of the diaphragm wall.

2. The method according to claim 1, characterized in that, The calculation expression for calculating the shield jacking force according to the soil layer parameters and shield parameters is: ； Among them, F f is the frictional force between the shield machine shell and the soil, F T is the mud pressure on the working face, F G is the penetration resistance received by the cutting edge, and F is the shield thrust force.

3. The method according to claim 2, wherein The calculation expression for the frictional force between the shield machine shell and the soil is: ； Wherein, μ1 is the friction coefficient, N1 and N2 are the left-right and up-down normal earth pressures acting on the unit soil body of the shield shell respectively, and L is the length of the shield; The calculation expression for the mud pressure on the working face is: ； where D is the radius, ν1 is the Poisson's ratio of the soil, q e is the pressure value on the inner wall of the soil bin, a is the length of the soil bin, is the Poisson's ratio of the soil, φ is the internal friction angle of the soil, and ω is the cutter head opening ratio; The calculation expression for the penetration resistance received by the cutting edge is: ； where α, z1, z2, and z3 are coefficients to be determined, and τ p is the shear strength of the shield soil mass.

4. The method according to claim 1, characterized in that, The calculation expression for calculating the ground heave volume based on the deformation of the diaphragm wall and the proportionality coefficient is: ； where Mu is the proportionality coefficient and V S is the volume of ground heave.

5. The method according to claim 1, wherein The calculation expression for calculating the maximum value of the ground heave based on the ground heave volume is: ； Among them, S max is the maximum deformation value, x is the horizontal displacement, x m is the distance from the position of the maximum deformation amount, x0 is the horizontal deformation influence range, y is the vertical displacement, and y0 is the vertical deformation influence range.

6. The method according to claim 1, wherein The calculation expression for calculating the deformation of any point on the ground based on the maximum value of the ground heave is: ； Wherein, S is the deformation of any point on the ground.

7. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1-6.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the method according to any one of claims 1-6.

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