Failure mode analysis method and device for tunnel excavation surface in heterogeneous strata

Abstract

The embodiments of the present application provide a method, device, equipment and computer-readable storage medium for analyzing the failure mode of a tunnel excavation face in a heterogeneous stratum. The method includes constructing a failure mechanism of a tunnel excavation face based on the buried depth data and diameter data of the tunnel; converting the failure mechanism into an initial grid; constructing an upper limit analysis mechanical model of a tunnel motion unit based on the initial grid; inputting the initial grid and preset constraints into the upper limit analysis mechanical model of the tunnel motion unit to obtain a critical load coefficient and a failure form of a slip line network; extracting the failure mode of the current tunnel excavation face based on the critical load coefficient and the failure form of a slip line network. In this way, the calculation error is reduced, providing clear data support for the quantitative analysis of the surrounding rock stability of the tunnel excavation face, and facilitating the formulation of auxiliary engineering implementation plans.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of failure mode analysis, and in particular, to a failure mode analysis method, device, equipment, and computer-readable storage medium for a tunnel excavation surface in heterogeneous strata. Background Art

[0002] As one of the most classic geotechnical analysis models, the circular tunnel stability problem has a wide range of applications. For tunnels buried in undrained clay strata, the excavation surface is more damaged than that of sandy strata, and the corresponding safety risk increases accordingly. In addition, the soil sediment particles deform under repeated loading and unloading, resulting in uneven strength distribution of natural clay strata. For example, the cohesion of pure clay increases with depth under undrained conditions. Therefore, quantitative analysis of the potential damage morphology and evolution law of clay strata with linear increase in shear strength with depth induced by tunnel excavation can provide data support for the formulation of tunnel support schemes, analysis of failure mechanisms, and optimization of tunnel construction.

[0003] The main technical issues in the current stability analysis method of circular tunnel excavation face in heterogeneous clay strata include:

[0004] 1. It is difficult to accurately simulate the boundary line of the circular tunnel excavation surface;

[0005] 2. The failure pattern of the tunnel excavation surface cannot be quantitatively analyzed.

[0006] The traditional rigid slider upper limit method is often implemented by pre-constructing the failure mechanism. Regarding the various failure modes of circular tunnels, a few rigid blocks are used to calculate the critical stability coefficient of the tunnel. However, these failure modes have a certain gap with the actual stratum deformation, especially the failure form around the tunnel.

[0007] The limit analysis finite element method combined with the finite element concept can accurately determine the arc boundary at the location of the circular tunnel excavation surface, and characterize the stratum deformation around the tunnel with an adaptive grid distribution map. However, the failure morphology of the excavation surface is highly dependent on the adaptive grid distribution map or the dissipated energy cloud map, and it is not easy to quantitatively analyze the failure mode.

[0008] As a classic geotechnical analysis theory, the slip line method has certain advantages in quantitative analysis, that is, the slip line method can obtain the failure boundary represented by characteristic lines. However, the strict slip line field theory requires that both the velocity field and the stress field be satisfied. Therefore, the current research objects of the slip line method are mostly concentrated on the bearing capacity of the foundation. For the stability of the tunnel excavation face with complex boundary conditions, especially when considering the heterogeneity of the formation, there are few related studies.

[0009] The rigid body translational motion unit upper limit method, which is based on the generalization of the rigid slider upper limit method, once considered dividing the tunnel calculation model with unstructured grids, and combining the rigid block failure mechanism obtained by nonlinear programming operations to obtain more detailed stratum failure forms. However, the unstructured grid is not prominent enough in the key area of ​​tunnel excavation face failure, and a large number of invalid discontinuities are generated in non-critical areas, which hinders the calculation efficiency. Summary of the invention

[0010] According to the embodiments of the present application, a failure mode analysis scheme for the excavation surface of a tunnel in a heterogeneous stratum is provided, in which the original rigid body translational motion method is improved, the unstructured grid division method is abandoned, and a minimalist rigid block failure mechanism is used as the starting point. The grid division is clearly divided into primary and secondary, and the rigid slider failure mechanism of the sliding network division is obtained by multiple iterative updates and calculations. The number of rigid sliders is greatly increased compared with the traditional method, which effectively reflects the displacement field around the tunnel, and can make the failure characteristics consistent with the slip line method. The boundary of the failure area can be quantitatively determined by the mesh velocity discontinuity line, which is conducive to the quantitative analysis of the failure morphology.

[0011] In a first aspect of the present application, a failure mode analysis method for a tunnel excavation surface in a heterogeneous stratum is provided. The method comprises:

[0012] Based on the tunnel's buried depth and diameter data, construct the failure mechanism of the tunnel excavation surface;

[0013] Converting the destruction mechanism into an initial grid;

[0014] Based on the initial grid, constructing an upper limit analysis mechanical model of the tunnel motion unit;

[0015] Inputting the initial grid and the preset constraint conditions into the tunnel motion unit upper limit analysis mechanical model to obtain the critical load coefficient and the failure form of the slip line network;

[0016] Based on the critical load factor and the failure form of the slip line network, the failure mode of the current tunnel excavation face is extracted.

[0017] Furthermore, the construction of a destruction mechanism for the tunnel excavation surface based on the tunnel burial depth data and diameter data includes:

[0018] Based on the buried depth and diameter data of the tunnel, an irregular pentagonal rigid block is constructed;

[0019] Based on the pentagonal rigid block, construct a first triangular block and a second triangular block;

[0020] The pentagonal rigid block, the first triangular block and the second triangular block are combined to obtain a destruction mechanism of the tunnel excavation surface.

[0021] Furthermore, converting the destruction mechanism into an initial grid includes:

[0022] Obtain engineering data for the tunnel;

[0023] Based on the engineering data, setting the boundary size, dimensionless gravity parameter and formation heterogeneity parameter of the tunnel;

[0024] Based on the boundary size of the tunnel, the dimensionless weight parameter and the formation heterogeneity parameter, the destruction mechanism is converted into an initial grid.

[0025] Furthermore, the objective function of the upper limit analysis mechanical model of the tunnel motion unit is:

[0026]

[0027] Among them, P c The energy dissipated by the speed discontinuity line;

[0028] P y is the virtual power of soil weight;

[0029] n d is the total number of model velocity discontinuities;

[0030] n e is the total number of units;

[0031] A i is the area of ​​the ith unit.

[0032] Furthermore, the constraint function includes:

[0033] Velocity discontinuity plastic flow constraint conditions:

[0034] ξ′ i +ξ″ i ≥0;ξ″ i -ξ′≥0,(i=1,…,n d )

[0035] Velocity boundary conditions:

[0036]

[0037]

[0038] Geometric constraints:

[0039] -A i ≤0,(i=1,…,n e )

[0040] Boundary geometry constraints:

[0041] yi =f(x i ),(i=1,…,n b )

[0042] Among them, n y is the total number of cells on the velocity boundary;

[0043] n b is the total number of nodes on the geometric boundary;

[0044] ξ' i and ξ″ i is an intermediate variable.

[0045] Furthermore, before constructing the tunnel motion unit upper limit analysis mechanical model based on the initial grid, the method further includes:

[0046] Based on the boundary size of the tunnel, a magnetic adsorption area is constructed;

[0047] Based on the magnetic attraction area, a region for calculating an initial grid is determined.

[0048] Furthermore, the step of constructing a magnetic adsorption area based on the boundary size of the tunnel includes:

[0049] Based on the boundary dimensions of the tunnel, determine the circular boundary of the excavation face;

[0050] By extracting fitting points, the circular boundary is replaced with multiple straight lines;

[0051] Connect multiple straight lines of the excavation surface to form a closed calculation model boundary;

[0052] Based on the calculation model boundary, a magnetic adsorption area is constructed.

[0053] In one possible implementation,

[0054] In a second aspect of the present application, a failure mode analysis device for a tunnel excavation surface in a heterogeneous stratum is provided. The device comprises:

[0055] A construction module, used to construct a destruction mechanism of the tunnel excavation surface based on the tunnel's buried depth data and diameter data;

[0056] A conversion module, used for converting the destruction mechanism into an initial grid;

[0057] A construction module, for constructing an upper limit analysis mechanical model of a tunnel motion unit based on the initial grid;

[0058] An analysis module, used to input the initial grid and preset constraint conditions into the tunnel motion unit upper limit analysis mechanical model to obtain the critical load coefficient and the failure form of the slip line network;

[0059] The extraction module is used to extract the failure mode of the current tunnel excavation face based on the critical load coefficient and the failure form of the slip line network.

[0060] In a third aspect of the present application, an electronic device is provided, which includes a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the program, the method described above is implemented.

[0061] In a fourth aspect of the present application, a computer-readable storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the method according to the first aspect of the present application is implemented.

[0062] The method for analyzing the failure mode of a tunnel excavation face in a heterogeneous stratum provided in an embodiment of the present application constructs a failure mechanism of the tunnel excavation face based on the buried depth and diameter data of the tunnel; converts the failure mechanism into an initial grid; constructs an upper limit analysis mechanical model of a tunnel motion unit based on the initial grid; inputs the initial grid and preset constraints into the upper limit analysis mechanical model of the tunnel motion unit to obtain a critical load coefficient and a failure form of a slip line network; extracts the failure mode of the current tunnel excavation face based on the critical load coefficient and the failure form of the slip line network, reduces calculation errors, provides clear data support for quantitative analysis of the stability of the surrounding rock of the tunnel excavation face, and facilitates the formulation of auxiliary engineering implementation plans.

[0063] It should be understood that the contents described in the Summary of the Invention are not intended to limit the key or important features of the embodiments of the present application, nor are they intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The above and other features, advantages and aspects of the embodiments of the present application will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, wherein:

[0065] Figure 1 is a flow chart of a failure mode analysis method for a tunnel excavation face in a heterogeneous stratum according to an embodiment of the present application;

[0066] Figure 2 A schematic diagram of stability calculation of a circular tunnel excavation face in a heterogeneous clay stratum according to an embodiment of the present application;

[0067] Figure 3 A diagram of a semi-structural calculation model for calculating the stability of a circular tunnel excavation face in a heterogeneous clay stratum according to an embodiment of the present application;

[0068] Figure 4It is a schematic diagram of the linear increase of undrained shear strength of clay with depth on the velocity discontinuity line according to an embodiment of the present application;

[0069] Figure 5 A schematic diagram of a preset extremely simplified failure form of a circular tunnel excavation surface in a heterogeneous clay stratum according to an embodiment of the present application;

[0070] Figure 6 A schematic diagram of the magnetic adsorption geometric boundary of a circular tunnel excavation surface in a heterogeneous clay stratum according to an embodiment of the present application;

[0071] Figure 7 A schematic diagram of initial grid and unit information of a circular tunnel excavation surface in a heterogeneous clay stratum according to an embodiment of the present application;

[0072] Figure 8 It is a schematic diagram of initial grid and unit information after nonlinear programming calculation of circular tunnel excavation surface in heterogeneous clay stratum according to an embodiment of the present application;

[0073] Fig. 9 A schematic diagram of a flow chart of a motion unit grid update process for a circular tunnel excavation face in a heterogeneous clay stratum according to an embodiment of the present application;

[0074] Fig.10 A schematic diagram of the destruction morphology corresponding to the update of the motion unit grid of the circular tunnel excavation face in the heterogeneous clay stratum according to an embodiment of the present application;

[0075] Fig.11 It is a schematic diagram of extracting quantitative indicators of the destruction morphology of a circular tunnel excavation surface in a heterogeneous clay stratum according to an embodiment of the present application;

[0076] Fig.12 is a block diagram of a failure mode analysis device for a tunnel excavation face in a heterogeneous stratum according to an embodiment of the present application;

[0077] Fig.13 It is a schematic diagram of the structure of a terminal device or a server suitable for implementing the embodiments of the present application. DETAILED DESCRIPTION

[0078] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0079] In addition, the term "and / or" in this article is only a description of the association relationship between the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0080] Figure 1 A flow chart of a failure mode analysis method for a tunnel excavation face in a heterogeneous stratum according to an embodiment of the present disclosure is shown. The method comprises:

[0081] S110, constructing a destruction mechanism of the tunnel excavation surface based on the buried depth data and diameter data of the tunnel.

[0082] In some embodiments, the buried depth data and diameter data of the tunnel can be obtained through the engineering data of the construction site; the engineering data can be obtained through construction drawings and the like, which is not further limited here.

[0083] In some embodiments, a minimalist destruction mechanism for a undrained clay stratum tunnel (destruction mechanism of the tunnel excavation surface) is constructed according to the tunnel burial depth and tunnel diameter, and the area from directly above the tunnel to the surface is set as an irregular pentagonal rigid block n1n3n4n5n2. The first rigid block n3n4n6 and the second rigid block n4n5n6 are continued to be drawn below the pentagonal rigid block. The pentagonal block n1n3n4n5n2 and the first and second triangular blocks n3n4n6 and n4n5n6 are combined to form a minimalist rigid block destruction mechanism, and the corresponding absolute velocities are V1-V3 respectively.

[0084] S120, converting the destruction mechanism into an initial grid.

[0085] In some embodiments, the boundary size of the stability of the circular tunnel in the heterogeneous stratum, the dimensionless weight parameter, and the stratum heterogeneity parameter are set through engineering data. The boundary nodes are connected, the destruction mechanism constructed by step S110 is converted into an initial grid for the upper limit analysis of the motion unit, and the pentagonal block n1n3n4n5n2 is split into 3 triangular units. At this time, only triangular grids exist in the initial grid.

[0086] Furthermore, common edges between adjacent cells are extracted and used as velocity discontinuities. The information of cells, nodes and velocity discontinuities of the initial grid is integrated.

[0087] S130, constructing an upper limit analysis mechanical model of the tunnel motion unit based on the initial grid.

[0088] In some embodiments, in order to fit the circular boundary of the excavation surface, the arc line may be replaced by multiple straight lines.

[0089] The polyline is formed by extracting N fitting points at equal intervals on the arc line and connecting the fitting points to form a polyline, which is the potential geometric boundary of the excavation surface. In order to ensure the accuracy of the calculation, N is usually greater than 5000.

[0090] Connect the polyline at the excavation surface with the geometric boundaries at other locations to form a closed calculation model boundary, and expand it on both sides of the closed geometric boundary to form a geometric adsorption area; the expansion length is preferably 10 -4 .

[0091] Furthermore, the excavation surface area and the stratum area are separated by geometric boundaries. The nodes located in the excavation surface area are automatically adsorbed to the geometric boundary during nonlinear programming operations, and the nodes located in the stratum area are also automatically adsorbed to the geometric boundary when they are close to the geometric boundary, forming a magnetic adsorption area. That is, magnetic adsorption areas are set on both sides of the geometric boundary.

[0092] In some embodiments, an upper limit analysis mechanical model of the circular tunnel motion unit is established based on the initial grid information in the calculation domain (magnetic adsorption area).

[0093] Specifically, the upper limit analysis mechanical model of the circular tunnel motion unit includes:

[0094] When calculating the dissipated energy of the discontinuity line, the undrained shear strength increases linearly with depth:

[0095]

[0096] Among them, c u0 is the shear strength at the surface;

[0097] ρ is the strength growth coefficient along the vertical downward direction;

[0098] Calculate the dissipated energy power P on the i-th speed discontinuity line c,i When , the integral along the entire length of the velocity discontinuity line is:

[0099]

[0100] in, is the normal velocity difference on the i-th velocity discontinuity line;

[0101] Since the shear strength of the soil changes linearly in the y direction, the vertical coordinate y can be taken as the midpoint value of each velocity discontinuity line, and the integral of the above formula can be further simplified to:

[0102]

[0103] Based on associated flow constraints Further transform the above formula into:

[0104]

[0105] In this disclosure, in order to facilitate subsequent calculation and analysis, two intermediate variables are set:

[0106]

[0107] ξ″ i =u r,i (x 2,i -x 1,i )+v r,i (y 2,i -y 1,i )+u l,i (x 1,i -x 2,i )+v l,i (y 1,i -y 2,i )

[0108] Among them, n d is the total number of model velocity discontinuities;

[0109] u r,i and v r,i is the unit velocity component on the clockwise side of the i-th velocity discontinuity line;

[0110] u l,i and v l,i is the component corresponding to the counterclockwise direction;

[0111] x 1,i and 1,i is the starting point coordinate of the i-th speed discontinuity line;

[0112] x 2,i and 2,i is the end point coordinate;

[0113] The calculation formula for the dissipated energy and power of the i-th speed discontinuity line is obtained:

[0114] P c,i =c u,i (y)ξ′ i

[0115] Sum the energy dissipated by the velocity discontinuity lines in the computational domain:

[0116]

[0117] Virtual power of soil weight P γ The calculation is as follows:

[0118]

[0119] Among them, ne is the total number of units;

[0120] A i is the area of ​​the i-th unit. During the node movement, it is necessary to ensure that A i Always positive value;

[0121] A nonlinear programming model is established, where the decision variables are:

[0122] Rigid body unit velocity component: u i , v i (i=1,…,n e ), n e is the total number of units;

[0123] Grid node coordinate component: x i ,y i (i=1,…,n n ), n n is the total number of nodes;

[0124] The objective function of the mechanical model for the upper limit analysis of the tunnel motion unit is:

[0125]

[0126] Among them, P c The energy dissipated by the speed discontinuity line;

[0127] P y is the virtual power of soil weight;

[0128] n d is the total number of model velocity discontinuities;

[0129] n e is the total number of units;

[0130] A i is the area of ​​the ith unit.

[0131] S140, inputting the initial grid and the preset constraint conditions into the tunnel motion unit upper limit analysis mechanical model to obtain the critical load coefficient and the failure form of the slip line network.

[0132] In some embodiments, the following constraints may be set:

[0133] Velocity discontinuity plastic flow constraint conditions:

[0134] ξ′ i +ξ″ i ≥0;ξ″ i -ξ′≥0,(i=1,…,n d )

[0135] Velocity boundary conditions:

[0136]

[0137]

[0138] Geometric constraints:

[0139] -A i ≤0,(i=1,…,n e )

[0140] Boundary geometry constraints:

[0141] y i =f(x i ),(i=1,…,n b )

[0142] Among them, n y is the total number of cells on the velocity boundary;

[0143] n b is the total number of nodes on the geometric boundary;

[0144] ξ' i and ξ″ i is an intermediate variable.

[0145] In some embodiments, the initial grid and preset constraints are input into the tunnel motion unit upper limit analysis mechanical model to obtain the critical load coefficient and the failure form of the slip line network.

[0146] Specifically, a nonlinear programming operation is performed on the initial mesh to obtain an optimized initial mesh. The mesh around the circular excavation surface is encrypted multiple times, and the shape of the excavation surface is refined to obtain the prototype of the failure morphology of the circular tunnel excavation surface in heterogeneous strata. The small-angle deformed triangular units that appear in the mesh update are merged. Finally, the mesh in the calculation domain is encrypted as a whole to obtain a high-precision upper limit solution of the critical load coefficient and a mesh failure morphology of the slip line.

[0147] S150, extracting the failure mode of the current tunnel excavation face based on the critical load coefficient and the failure form of the slip line network.

[0148] In some embodiments, a subroutine is used to extract failure morphological feature data, and failure characteristic analysis indicators are introduced to achieve quantitative analysis of the stability failure morphology of a circular tunnel excavation face in a heterogeneous clay stratum.

[0149] Specifically, the velocity of each rigid block is identified, and the failure mode is divided into the overall rigid sinking zone and the cross-slip network failure zone based on the unit velocity.

[0150] The surface settlement width and stratum damage area of ​​the circular tunnel failure morphology in heterogeneous clay strata are extracted to achieve quantitative analysis of the failure morphology and extract the failure mode of the current tunnel excavation surface.

[0151] A specific embodiment according to the present disclosure is given below:

[0152] like Figure 2 As shown, Figure 2 The stability analysis model of tunnel excavation face under surface overload is shown. It can be simplified into a semi-structural plane strain problem during calculation. Figure 3 .

[0153] The main controlling factor of tunnel excavation face damage is assumed to be the uniformly distributed overload σ s , Excavation face support forceσ t , let σ t =0, and σ t Taking non-zero values ​​(σ s -σ t ) / C u0 The calculated values ​​are the same. The influencing factors are tunnel height D, burial depth C, soil bulk density γ, and undrained soil shear strength C. u , further, to simplify the analysis, the parameters are dimensionless. That is: the burial depth ratio C / D, the soil weight parameter γD / C u0 , soil heterogeneity strength parameter ρD / c u0 , critical load factor (σ s -σ t ) / C u0 .

[0154] According to the existing experimental data, the soil sediment particles deform under repeated loading and unloading, resulting in uneven strength distribution of natural clay strata. For example, the cohesion of pure clay increases linearly with depth under undrained conditions, making the stability analysis of tunnel excavation face complicated. Therefore, the linear increase of shear strength with depth is considered in this disclosure:

[0155]

[0156] In the calculation and analysis, the shear strength mainly affects the dissipated energy power on the velocity discontinuity line. Figure 4 .

[0157] It is assumed that a rigid lining is applied along the length of the tunnel as support, and the excavation face is free and unconstrained. The tunnel excavation face is vertical, the x and y coordinate axes represent the horizontal and vertical directions, and the origin is set as the midpoint of the excavation face; the horizontal and vertical velocity components u and v of the model are consistent with the x and y coordinate axes.

[0158] In the present disclosure, an example in which typical parameters are depth ratio C / D=4, dimensionless weight parameter γD / c=3, and soil heterogeneity strength parameter ρD / c=1 is used for explanation:

[0159] According to Figure 3 The mechanical model shown is used to construct the tunnel excavation face motion-permitted destruction mechanism in different regions. First, the rigid blocks n1n3n4n5n2 are constructed directly above the excavation face. Since the present disclosure considers undrained pure clay soil layers, that is, the internal friction angle φ=0°, the main sliding surfaces are all vertically downward; based on engineering experience, there is a destructive soil body in front of the excavation face, so triangular rigid blocks n3n4n6 and n4n5n6 are set in front of the excavation face. The aforementioned blocks are combined to form a minimalist block system destruction mechanism suitable for the excavation face of a tunnel in clay strata, and the corresponding absolute velocities are V1~V3 respectively; the corresponding block system destruction morphology, discontinuous line relative velocity vector closure diagram and block absolute velocity vector diagram can be referred to. Figure 5 .

[0160] According to the calculation parameters (determined by engineering data), the model is set to L1 = 20m, L2 = 50m, C = 40m, and D = 10m. According to the model boundary, the constructed multi-block destruction mechanism of the tunnel excavation surface is transformed into a plane triangulated network: the triangular blocks n3n4n6 and n4n5n6 remain unchanged, and the pentagonal block n1n3n4n5n2 above the excavation surface is split into 3 triangular rigid units.

[0161] In order to improve the calculation efficiency, in this paper, the arc boundary of the circular tunnel excavation surface is simplified. First, more than 5000 fitting points are extracted at equal distances on the arc boundary, connected to each other to form a polyline, and the polyline is connected to the model calculation boundary to form a closed geometric boundary. The closed geometric boundary is expanded by 10 -5 length, forming a square ring-shaped magnetic adsorption area such as Figure 6 As shown, the excavation area and the stratum area are separated by geometric boundaries. Figure 6 On the right side, when the grid node coordinates satisfy x 2 +y 2 ≤(D / 2) 2 When the condition is met, it is identified as an internal node of the excavation surface, otherwise it is an internal node of the stratum. For the internal nodes of the excavation surface, they will be automatically adsorbed to the geometric boundary of the excavation surface in the subsequent nonlinear programming operation, and the nodes located in the stratum area will also be adsorbed to the geometric boundary when they are close to the geometric boundary to avoid the generation of deformed units.

[0162] Analyze and extract the common edges (i.e. potential velocity discontinuity lines) of all adjacent triangular rigid blocks to generate the initial mesh reference Figure 5, renumber all unit nodes, node numbers are 1, 2, 3..., 12, unit numbers are 1, 2,..., 12, and speed discontinuity lines are 1, 2,..., 13. Record and store unit, node, and speed discontinuity line information, refer to Figure 5 .

[0163] based on Figure 5 The initial grid shown in the figure imports the grid information and constraints into the nonlinear programming model, automatically searches for the optimal failure mode, and obtains the critical overload coefficient σ s / C u0 is 8.274, corresponding to the optimized grid reference Figure 6 ,contrast Figure 5 It can be seen that some nodes are moved to a better position, and the nodes at the excavation face position are adsorbed to the circular tunnel boundary. At this point, the optimized initial mesh is ready for subsequent motion unit mesh updates.

[0164] The initial grid and unit information can be found in Figure 7 , Figure 7 The initial mesh and cell information of the circular tunnel excavation face in heterogeneous clay strata are shown.

[0165] The motion unit grid update is a process in which the grid update operation and the nonlinear programming operation are implemented alternately. Figure 8 As shown, Figure 8 The figure shows the initial mesh and unit information after nonlinear programming of the circular tunnel excavation surface in heterogeneous clay strata. Fig. 9 , Fig. 9 The moving unit grid update process of the circular tunnel stability problem in heterogeneous clay strata is shown. Fig. 9 The figure below is an enlarged view of the mesh division near the circular excavation surface after each update. First, the mesh of the main damage area in front of the excavation surface is initially encrypted, and two nodes are added to the circular excavation surface area. After nonlinear programming calculation (σ s -σ t ) / C u0 Reduced to 7.365, we get Fig. 9 The grid shown.

[0166] Furthermore, the front of the main damage area is encrypted and nodes are added at the excavation surface. The mesh after nonlinear programming operation is shown in Fig. 9 (b), (σ s -σ t ) / C u0 The value of the grid is reduced to 7.182. At this time, triangular units with small sharp angles appear. These units are identified and eliminated through mesh merging. After nonlinear programming operation, the grid diagram is as follows: Fig. 9 (c) shows, (σ s -σt ) / C u0 It increases to 7.223. According to the upper limit, the accuracy is known to decrease, but this treatment can facilitate the subsequent mesh update. It is recognized that the mesh above the main damage area is sparse, and nodes are added to the main damage surface on the right side, and connected with the surrounding nodes to form a new unit to achieve the mesh expansion upward. Later, because the mesh in the extended area is sparse, the area is encrypted again, and nodes are continued to be added at the circular excavation surface. After nonlinear programming calculation, the mesh diagram is as follows Fig. 9 As shown in (e), (σ s -σ t ) / C u0 The excavation surface boundary is initially in the shape of an arc, but there is still a problem of abrupt transition. The grid in the computational domain is encrypted as a whole. After nonlinear programming, the grid is as follows: Fig. 9 (f) as shown in (σ s -σ t ) / C u0 It drops to 6.599. At this time, the mesh density in the computational domain is high, the excavation surface boundary is very close to the arc, and the mesh update accuracy is improved less than the previous one, and the motion unit mesh update is completed.

[0167] It should be noted that if Fig.10 As shown, Fig.10 The failure form of the superimposed velocity field is shown. In the upper limit analysis of the motion unit, not all units on both sides of the velocity discontinuity line have effective relative displacement. The discontinuity lines are classified by dissipated energy density, and the invalid discontinuity lines with low dissipated energy are hidden. The remaining effective velocity discontinuity lines are connected to form an optimized rigid block system, which can be regarded as the failure form calculated by the upper limit analysis of the motion unit. The superimposed velocity on the rigid block unit represents the deformation trend when the formation is destroyed, where n' d is the corresponding number of valid discontinuous lines.

[0168] After the grid is updated, the corresponding burial depth ratio C / D = 4, the dimensionless weight parameter γD / c = 3, and the soil heterogeneous strength parameter ρD / c = 1 are obtained. Fig.11 As shown in the figure, the slip line network failure form formed by the effective velocity discontinuity lines, and its clear velocity discontinuity lines provide convenience for extracting failure characteristics. The internal discontinuity lines are hidden, and the surface settlement width and failure area are identified according to the unit velocity. The dimensionless quantitative index of the failure form, the surface settlement width l, is introduced. d / D and the formation damage area Sf / Sc, calculate l d / D=3.12,S f / S c =16.53.

[0169] In the present disclosure, the failure morphology is inherited. If other multi-parameter calculation and analysis is required, it is not necessary to fully implement each set of parameters. Fig. 9 The refinement iterations shown. Fig. 9 (f) The corresponding grid is used as the initial grid for calculation and analysis, and then the above process is continued to reduce the iteration workload.

[0170] According to the embodiments of the present disclosure, the following technical effects are achieved:

[0171] The circular excavation surface is refined through the mesh updating process, and the excavation surface position boundary in the calculation result coincides with the circular boundary, which reduces the calculation error.

[0172] The fine staggered slip line network of the tunnel excavation face soil obtained by iterative refinement based on the minimalist triangulated network has clear failure boundaries and failure characteristics. The failure characteristics are extracted, and quantitative indicators of failure morphology are introduced, which provides clear data support for the quantitative analysis of the stability of the surrounding rock of the tunnel excavation face, and is more conducive to the formulation of auxiliary engineering implementation plans.

[0173] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that the present application is not limited by the described order of actions, because according to the present application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present application.

[0174] The above is an introduction to the method embodiment. The following is a further explanation of the scheme described in this application through an apparatus embodiment.

[0175] Fig.12 The block diagram 1200 showing the failure mode analysis device for a tunnel excavation face in a heterogeneous stratum according to an embodiment of the present application includes:

[0176] A construction module 1210 is used to construct a destruction mechanism of the tunnel excavation surface based on the buried depth data and diameter data of the tunnel;

[0177] A conversion module 1220, used to convert the destruction mechanism into an initial grid;

[0178] A construction module 1230 is used to construct an upper limit analysis mechanical model of a tunnel motion unit based on the initial grid;

[0179] The analysis module 1240 is used to input the initial grid and the preset constraint conditions into the tunnel motion unit upper limit analysis mechanical model to obtain the critical load coefficient and the failure form of the slip line network;

[0180] The extraction module 1250 is used to extract the failure mode of the current tunnel excavation face based on the critical load coefficient and the failure form of the slip line network.

[0181] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the described module can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0182] Fig.13 A schematic diagram of the structure of a terminal device or server suitable for implementing an embodiment of the present application is shown.

[0183] like Fig.13 As shown, the terminal device or server includes a central processing unit (CPU) 1301, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 1302 or the program loaded from the storage part 1308 to the random access memory (RAM) 1303. In the RAM 1303, various programs and data required for the operation of the terminal device or server are also stored. The CPU 701, ROM 1302 and RAM 1303 are connected to each other through a bus 1304. An input / output (I / O) interface 1305 is also connected to the bus 1304.

[0184] The following components are connected to the I / O interface 1305: an input section 1306 including a keyboard, a mouse, etc.; an output section 1307 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 1308 including a hard disk, etc.; and a communication section 1309 including a network interface card such as a LAN card, a modem, etc. The communication section 1309 performs communication processing via a network such as the Internet. A drive 1310 is also connected to the I / O interface 1305 as needed. A removable medium 1311, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 1310 as needed, so that a computer program read therefrom is installed into the storage section 1308 as needed.

[0185] In particular, according to an embodiment of the present application, the above method flow steps can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a machine-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 1309, and / or installed from the removable medium 1311. When the computer program is executed by the central processing unit (CPU) 1301, the above-mentioned functions defined in the system of the present application are executed.

[0186] It should be noted that the computer-readable medium shown in the present application may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system, device or device. In the present application, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries a computer-readable program code. This propagated data signal may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. The program code contained on the computer-readable medium may be transmitted using any appropriate medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0187] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each box in the flow chart or block diagram can represent a module, a program segment or a part of the code, and the aforementioned module, program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0188] The units or modules involved in the embodiments described in the present application may be implemented by software or hardware. The units or modules described may also be arranged in a processor. The names of these units or modules do not, in some cases, constitute limitations on the units or modules themselves.

[0189] As another aspect, the present application further provides a computer-readable storage medium, which may be included in the electronic device described in the above embodiment; or may exist independently without being assembled into the electronic device. The above computer-readable storage medium stores one or more programs, and when the above programs are used by one or more processors to execute the method described in the present application.

[0190] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of application involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the aforementioned application concept. For example, the above features are replaced with (but not limited to) technical features with similar functions applied in the present application.

Claims

1. A failure mode analysis method for tunnel excavation surface in heterogeneous strata, characterized in that: include: Based on the tunnel depth and diameter data, the destruction mechanism of the tunnel excavation surface is constructed, including: Based on the buried depth and diameter data of the tunnel, an irregular pentagonal rigid block is constructed; Based on the pentagonal rigid block, construct a first triangular block and a second triangular block; The pentagonal rigid block, the first triangular block and the second triangular block are combined to obtain a destruction mechanism of the tunnel excavation surface; Converting the destruction mechanism into an initial grid; Based on the initial grid, constructing an upper limit analysis mechanical model of the tunnel motion unit; The initial grid and the preset constraints are input into the tunnel motion unit upper limit analysis mechanical model to obtain the critical load coefficient and the failure form of the slip line network, including: Performing nonlinear programming operation on the initial grid to obtain an optimized initial grid; Based on the optimized initial mesh, the mesh around the excavation surface is encrypted multiple times, and the shape of the excavation surface is refined to obtain the prototype of the destruction morphology of the circular tunnel excavation surface in the heterogeneous stratum; Based on the prototype of the destruction morphology of the circular tunnel excavation surface in the heterogeneous stratum, the small-angle deformed triangular units appearing in the grid update are merged; After the merging process is completed, the grid in the computational domain is encrypted as a whole to obtain a high-precision upper limit solution of the critical load factor and a mesh failure form of the slip line; Based on the critical load factor and the failure form of the slip line network, the failure mode of the current tunnel excavation face is extracted.

2. The method according to claim 1, characterized in that The converting the destruction mechanism into an initial grid comprises: Obtain engineering data for the tunnel; Based on the engineering data, setting the boundary size, dimensionless gravity parameter and formation heterogeneity parameter of the tunnel; Based on the boundary size of the tunnel, the dimensionless weight parameter and the formation heterogeneity parameter, the destruction mechanism is converted into an initial grid.

3. The method according to claim 2, characterized in that The objective function of the upper limit analysis mechanical model of the tunnel motion unit is: Among them, P c The energy dissipated by the speed discontinuity line; P y is the virtual power of soil weight; n d is the total number of model speed discontinuities; n e is the total number of units; A i is the area of ​​the i-th unit; σ s The overload is evenly distributed on the surface; C is the burial depth; γ is the soil bulk density; ξ i ′ is a preset intermediate variable.

4. The method according to claim 3, characterized in that The constraints include: Velocity discontinuity plastic flow constraint conditions: x i ′+ξ i ″≥0;ξ i ″-ξ′≥0,i=1,…,n d Velocity boundary conditions: Geometric constraints: -A i ≤0,i=1,…,n e Boundary geometry constraints: y i =f(x i ),i=1,…,n b Among them, n v is the total number of cells on the velocity boundary; n b is the total number of nodes on the geometric boundary; ξ i ′ and i ″ is an intermediate variable.

5. The method according to claim 4, characterized in that Before constructing the tunnel motion unit upper limit analysis mechanical model based on the initial grid, the method further includes: Based on the boundary size of the tunnel, a magnetic adsorption area is constructed; Based on the magnetic attraction area, a region for calculating an initial grid is determined.

6. The method according to claim 5, characterized in that The step of constructing a magnetic adsorption area based on the boundary size of the tunnel includes: Based on the boundary dimensions of the tunnel, determine the circular boundary of the excavation face; By extracting fitting points, the circular boundary is replaced with multiple straight lines; Connect multiple straight lines of the excavation surface to form a closed calculation model boundary; Based on the calculation model boundary, a magnetic adsorption area is constructed.

7. A failure mode analysis device for tunnel excavation surface in heterogeneous strata, characterized in that: include: The construction module is used to construct the destruction mechanism of the tunnel excavation face based on the tunnel's buried depth data and diameter data, including: Based on the buried depth and diameter data of the tunnel, an irregular pentagonal rigid block is constructed; Based on the pentagonal rigid block, construct a first triangular block and a second triangular block; The pentagonal rigid block, the first triangular block and the second triangular block are combined to obtain a destruction mechanism of the tunnel excavation surface; A conversion module, used for converting the destruction mechanism into an initial grid; A construction module, for constructing an upper limit analysis mechanical model of a tunnel motion unit based on the initial grid; The analysis module is used to input the initial grid and the preset constraint conditions into the upper limit analysis mechanical model of the tunnel motion unit to obtain the critical load coefficient and the failure form of the slip line network, including: Performing nonlinear programming operation on the initial grid to obtain an optimized initial grid; Based on the optimized initial mesh, the mesh around the excavation surface is encrypted multiple times, and the shape of the excavation surface is refined to obtain the prototype of the destruction morphology of the circular tunnel excavation surface in the heterogeneous stratum; Based on the prototype of the destruction morphology of the circular tunnel excavation surface in the heterogeneous stratum, the small-angle deformed triangular units appearing in the grid update are merged; After the merging process is completed, the grid in the computational domain is encrypted as a whole to obtain a high-precision upper limit solution of the critical load factor and a mesh failure form of the slip line; The extraction module is used to extract the failure mode of the current tunnel excavation face based on the critical load coefficient and the failure form of the slip line network.

8. An electronic device comprising a memory and a processor, wherein a computer program is stored in the memory, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 6 is implemented.

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

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