A near-field dynamics particle passivation and activation method for simulating the supporting effect of tunnel excavation

Abstract

The application discloses a kind of near-field dynamics particle passivation and activation method simulating tunnel excavation support effect, it is related to tunnel excavation technical field, this near-field dynamics particle passivation and activation method includes: according to near-field dynamics material parameter and fracture parameter establishes near-field dynamics constitutive force function;According to tunnel structured parameter determines tunnel excavation and support area, excavation and support area is discretized into particle, and according to particle attribute classification generates excavation and support space coordinate matrix;Utilize scalar subsection function to correct near-field dynamics constitutive force function, obtain modified near-field dynamics constitutive force function;Tunnel excavation and support simulation are realized by particle passivation and activation technology.The original particle of excavation and support area is passivated and activated by the application, to ensure that the attribute and coordinate of particle remain unchanged, so as to avoid the complex process of generating new particle and its attribute judgment and information storage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tunnel excavation, in particular to a near-field dynamics particle passivation and activation method for simulating the effect of tunnel excavation and support. BACKGROUND

[0002] As a new non-local action theory, near-field dynamics discretizes the solving region into material points with certain physical and mechanical information, and represents the deformation and failure of materials according to the spatial position change of the material points and the interaction between adjacent material points. Since the motion equation of near-field dynamics is in integral form, it overcomes the singularity problem in solving discontinuous problems with traditional numerical methods, and theoretically does not have special requirements for the size of the non-local action range, so that near-field dynamics can describe a series of mechanical behaviors from continuity to discontinuity and from micro to macro, and is particularly suitable for solving damage and failure problems of solid materials. The above-mentioned non-local action idea enables near-field dynamics to better reproduce the random evolution process of solid material cracking and damage, and has attracted widespread attention in the study of damage evolution of tunnel surrounding rock and lining.

[0003] The stress deformation of a tunnel structure is often closely related to its construction process. The construction process of a tunnel project mainly includes excavation and support. Among them, tunnel excavation unloading is one of the main reasons for causing surrounding rock instability and inducing various geological disasters; the role of tunnel support is to resist the continuous deformation of surrounding rock, so as to provide support force for the stability of surrounding rock under multi-axial stress state. Therefore, whether the tunnel excavation and support process can be accurately simulated is crucial to the exploration of the cracking and damage evolution mechanism of soft rock tunnel lining. However, due to the lack of a near-field dynamics method that can reflect the dynamic change process of tunnel excavation and support, the evolution mechanism of tunnel excavation disturbance and support load failure cannot be effectively revealed.

[0004] At present, there is no effective solution to the problems in the related art. SUMMARY

[0005] In view of the problems in the related art, the present application proposes a near-field dynamics particle passivation and activation method for simulating the effect of tunnel excavation and support, to overcome the above technical problems existing in the prior art.

[0006] To this end, the present application adopts the following specific technical solutions:

[0007] A near-field dynamics particle passivation and activation method for simulating the effect of tunnel excavation and support, the near-field dynamics particle passivation and activation method comprising:

[0008] calculating near-field dynamics material parameters and fracture parameters based on pre-collected tunnel structured parameters, and establishing a near-field dynamics constitutive force function according to the near-field dynamics material parameters and fracture parameters;

[0009] determining the tunnel excavation and support region according to the tunnel structural parameters, discretizing the excavation and support region into material points, and generating an excavation and support space coordinate matrix according to the material point attribute classification;

[0010] judging the domain range of the material points based on the excavation and support space coordinate matrix, constructing a scalar piecewise function according to the domain range of the material points, modifying the near-field dynamic constitutive force function by using the scalar piecewise function, and obtaining a modified near-field dynamic constitutive force function;

[0011] calculating and updating the characteristic parameters of the material points by using the central difference method, and realizing the tunnel excavation and support simulation through the material point passivation and activation technology;

[0012] judging the failure condition of the support region material point key in the tunnel excavation and support simulation, calculating the support cumulative damage based on the failure condition, and optimizing the simulation result according to the support cumulative damage.

[0013] Preferably, the tunnel structural characteristic parameters include tunnel geometric dimensions, surrounding rock parameters and lining parameters; and the near-field dynamic material parameters include micro-elastic modulus and critical elongation.

[0014] Preferably, the calculation formula of the micro-elastic modulus is:

[0015]

[0016] In the formula, c represents the micro-elastic modulus; E represents the elastic modulus of the material; h represents the thickness of the two-dimensional strain model; and δ represents the domain radius.

[0017] The calculation formula of the critical elongation is:

[0018]

[0019] In the formula, s0 represents the critical elongation; G0 represents the material fracture energy; κ represents the elastic parameter; and δ represents the domain radius.

[0020] Preferably, the determination of the tunnel excavation and support region according to the tunnel structural parameters, the discretization of the excavation and support region into material points, and the generation of the excavation and support space coordinate matrix according to the material point attribute classification include:

[0021] determining the region to be excavated and supported based on the tunnel geometric dimensions and the surrounding rock parameters, determining the cubic lattice size, and covering the calculation region by parallel arrangement of the cubic lattices;

[0022] judging the region to which the center point of the cubic lattice belongs as the material point coordinate;

[0023] The coordinates of the material points belonging to the excavation region are stored in an excavation material point dataset, and the coordinates of the material points belonging to the support region are stored in a support material point dataset.

[0024] Preferably, the domain range of the material point is determined based on the excavation and support spatial coordinate matrix, and a scalar piecewise function is constructed according to the domain range of the material point, the scalar piecewise function is used to modify the near-field dynamic constitutive force function to obtain a modified near-field dynamic constitutive force function, which includes:

[0025] The distance between the current material point and the adjacent material point is calculated based on the material point coordinates, and the number of other material points in the domain range of the material point is determined.

[0026] According to the domain range of the material point, a scalar piecewise function of the distance between the current material point and the adjacent material point in a preset time period is established.

[0027] The initial boundary conditions of the simulated tunnel excavation and support are applied, and the modified near-field dynamic constitutive force function is modified by using the scalar piecewise function to obtain a modified near-field dynamic constitutive force function.

[0028] Preferably, the distance between the current material point and the adjacent material point is calculated based on the material point coordinates, and the number of other material points in the domain range of the material point is determined.

[0029] The domain radius of the material point is determined, and the distance between the current material point and the adjacent material point is calculated according to the material point coordinates.

[0030] If the distance between the current material point and the adjacent material point is less than or equal to the domain radius, it indicates that there is an interaction force between the current material point and the adjacent material point, and the current material point is within the domain range of the material point, and the number of all material points within the domain range of the material point is counted.

[0031] If the distance between the current material point and the adjacent material point is greater than the domain radius, it indicates that there is no interaction force between the material point and the adjacent material point.

[0032] Preferably, the expression of the scalar piecewise function of the distance between the current material point and the adjacent material point in a preset time period is:

[0033]

[0034] In the formula, o(x i ,x j ,t) represents the scalar piecewise function of the distance between the current material point x i and the adjacent material point x j in a preset time period t; c0 represents the microscopic elastic modulus of the surrounding rock; c p represents the microscopic elastic modulus of the softening of the surrounding rock; and c aa micro elastic modulus of the lining.

[0035] Preferably, the expression of the constitutive force function of the near-field dynamics is modified as:

[0036]

[0037] wherein, o(x i ,x j ,t) represents a scalar piecewise function of the distance between the current material point x i and the neighboring material point x j in a preset time period t; μ represents a fracture parameter; s represents an elongation rate; ξ represents the relative position of the two material points in the initial reference configuration; η represents the relative displacement of the two material points in the current configuration; ξ+η represents the relative position of the two material points in the current configuration; || represents the modulus of a vector; c represents a micro elastic modulus.

[0038] Preferably, the tunnel excavation and support simulation by the material point deactivation and activation technology comprises:

[0039] If the scalar piecewise function o(x i ,x j ,t) is less than a preset threshold value, then the material point deactivation is realized, and the connection between the material points inside the excavation area and the non-excavation area is weakened, so as to realize the simulation effect of the tunnel excavation disturbance;

[0040] If the scalar piecewise function o(x i ,x j ,t) is greater than the preset threshold value, then the material point activation is realized, and the connection between the material points inside and outside the support area is enhanced, so as to simulate the support construction process;

[0041] If the scalar piecewise function o(x i ,x j ,t) is equal to the preset threshold value, then the force between the material points is not changed.

[0042] Preferably, in the tunnel excavation and support simulation, the failure condition of the support area material point key is judged in a loop, and the accumulated damage of the support is calculated based on the failure condition.

[0043] In the tunnel excavation and support simulation, the tensile strain between the current material point and the neighboring point is calculated, and the tensile strain is compared with the critical elongation rate;

[0044] If the tensile strain is greater than or equal to the critical elongation rate, then the material point key is failed, the number of failed keys is counted, and the ratio of the number of failed keys to the number of initial complete keys is calculated to obtain the accumulated damage value of the support; if the tensile strain is less than the critical elongation rate, then the material point key is not failed.

[0045] The beneficial effects of the present application are:

[0046] The present application ensures that the attributes and coordinates of the material points remain unchanged by passivating and activating the original material points in the excavation and support area, thereby avoiding the complex process of generating new material points and their attribute judgment and information storage, effectively improving the calculation efficiency, overcoming the low efficiency problem of the traditional near-field dynamics method in simulating the dynamic construction process of excavation and support, and modifying the constitutive force function by introducing a scalar piecewise function, which is simple in format, clear in physical meaning, and can more intuitively describe the mechanical behavior change of the excavation and support area. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0048] Figure 1 is a flowchart of a near-field dynamics material point passivation and activation method for simulating the effect of tunnel excavation and support according to an embodiment of the present application;

[0049] Figure 2 is a schematic diagram of a two-dimensional strain model in a near-field dynamics material point passivation and activation method for simulating the effect of tunnel excavation and support according to an embodiment of the present application;

[0050] Figure 3 is a schematic diagram of a two-dimensional strain model in a near-field dynamics material point passivation and activation method for simulating the effect of tunnel excavation and support according to an embodiment of the present application;

[0051] Figure 4 is a schematic diagram of a two-dimensional strain model in a near-field dynamics material point passivation and activation method for simulating the effect of tunnel excavation and support according to an embodiment of the present application;

[0052] Figure 5 is a schematic diagram of a two-dimensional strain model in a near-field dynamics material point passivation and activation method for simulating the effect of tunnel excavation and support according to an embodiment of the present application; DETAILED DESCRIPTION

[0053] To further illustrate the embodiments, the present application provides drawings, which are part of the disclosure of the present application, mainly used to illustrate the embodiments, and can explain the operating principle of the embodiments in conjunction with the related description of the specification. With reference to these contents, those skilled in the art should understand other possible embodiments and advantages of the present application.

[0054] According to an embodiment of the present application, a near-field dynamic particle passivation and activation method for simulating the supporting effect of tunnel excavation is provided.

[0055] The present application will be further described in conjunction with the drawings and specific embodiments, as shown in the drawings, the near-field dynamic particle passivation and activation method for simulating the supporting effect of tunnel excavation according to the embodiment of the present application, the near-field dynamic particle passivation and activation method comprises: Figure 1

[0056] S1, based on the pre-acquired tunnel structural parameters, the near-field dynamic material parameters and fracture parameters are calculated, and the near-field dynamic constitutive force function is established according to the near-field dynamic material parameters and fracture parameters.

[0057] Among them, the tunnel structural characteristic parameters include tunnel geometric dimensions, surrounding rock parameters and lining parameters, including tunnel excavation radius, Poisson, fracture energy of surrounding rock and lining, elastic modulus, density, Poisson's ratio; the near-field dynamic material parameters include micro-elastic modulus and critical elongation.

[0058] Among them, the calculation formula of micro-elastic modulus (two-dimensional model micro-elastic modulus) is:

[0059]

[0060] In the formula, c represents the micro-elastic modulus; E represents the elastic modulus of the material; h represents the thickness of the two-dimensional strain model; and δ represents the field radius.

[0061] The calculation formula of critical elongation (two-dimensional model critical elongation) is:

[0062]

[0063] In the formula, s0 represents the critical elongation; G0 represents the material fracture energy; κ represents the elastic parameter; and δ represents the field radius.

[0064] S2, according to the tunnel structural parameters, the tunnel excavation and support area is determined, the excavation and support area is discretized into particles, and the excavation and support space coordinate matrix is generated according to the particle attribute classification.

[0065] Among them, according to the tunnel structural parameters, the tunnel excavation and support area is determined, the excavation and support area is discretized into particles, and the excavation and support space coordinate matrix is generated according to the particle attribute classification, which comprises:

[0066] Based on the tunnel geometric dimensions and surrounding rock parameters, the area to be excavated and supported is determined, and the cubic lattice size is determined, and the calculation area is covered by parallel arrangement of cubic lattices;

[0067] ​The center point of the cubic lattice is taken as the material point coordinate, and the region to which the material point coordinate belongs is determined;

[0068] The material point coordinates belonging to the excavation region are stored in an excavation material point dataset, and the material point coordinates belonging to the support region are stored in a support material point dataset.

[0069] In order to facilitate the understanding of the above technical solutions of the present application, the following will be described in detail according to the tunnel structured parameters to determine the tunnel excavation and support regions, discretize the excavation and support regions into material points, and generate the excavation and support space coordinate matrices according to the material point attribute classification in the actual process.

[0070] The region to be excavated and the support region are determined, the calculation region is discretized, and the surrounding rock and support space coordinate matrices are generated according to the material point attribute classification, which includes:

[0071] The region to be excavated and the support region are determined according to the tunnel and surrounding rock geometric dimensions.

[0072] In the near-field dynamics theory, the analysis object is composed of a large number of material points with material information (material performance parameters, position, displacement, etc.), so these material points can be represented by a small number of cubic lattices with uniform specifications.

[0073] Discretizing the calculation region includes: determining the basic size of the cubic lattice; arranging these lattices in parallel, covering the discretized lattices in the calculation region, taking the center of each lattice as a spatial material point coordinate, determining whether its spatial distribution range belongs to the excavation or support region, and classifying and counting its coordinate matrix.

[0074] According to the material point attribute classification, the surrounding rock and support space coordinate matrices are generated, that is, according to the spatial position (material point coordinate) of the material point obtained by judgment in the excavation or support region, the material point coordinates belonging to the excavation region are stored in the excavation material point dataset, and the material point coordinates belonging to the support region are stored in another dataset. From the perspective of programming language, the dataset is an array, for example, coordinate[n][4].

[0075] S3, based on the excavation and support space coordinate matrices, the domain range of the material point is determined, and a scalar piecewise function is constructed according to the domain range of the material point, the near-field dynamics constitutive force function is modified by using the scalar piecewise function, and a modified near-field dynamics constitutive force function is obtained.

[0076] Among them, based on the excavation and support space coordinate matrices, the domain range of the material point is determined, and a scalar piecewise function is constructed according to the domain range of the material point, the near-field dynamics constitutive force function is modified by using the scalar piecewise function, and a modified near-field dynamics constitutive force function is obtained, which includes:

[0077] Calculate the distance between the current material point and the adjacent material point based on the material point coordinates, and determine the number of other material points in the material point field range.

[0078] The distance between the current material point and the adjacent material point is calculated based on the material point coordinates, and the number of other material points in the material point field range is determined.

[0079] Determine the material point field radius, and calculate the distance between the current material point and the adjacent material point based on the material point coordinates;

[0080] If the distance between the current material point and the adjacent material point is less than or equal to the field radius, it indicates that the current material point and the adjacent material point have mutual interaction force, and the current material point is a material point within the material point field range, and the number of all material points within the material point field range is counted.

[0081] If the distance between the current material point and the adjacent material point is greater than the field radius, it indicates that the material point and the adjacent material point do not have mutual interaction force.

[0082] According to the material point field range, a scalar piecewise function of the distance between the current material point and the adjacent material point in a preset time period is established.

[0083] Apply the initial boundary conditions of the simulated tunnel excavation and support, and modify the near-field dynamic constitutive force function using the scalar piecewise function to obtain the modified near-field dynamic constitutive force function.

[0084] In order to facilitate understanding of the above technical solutions of the present application, the following describes the determination of the material point field range based on the excavation and support spatial coordinate matrix, the construction of the scalar piecewise function based on the material point field range, and the modification of the near-field dynamic constitutive force function using the scalar piecewise function to obtain the modified near-field dynamic constitutive force function in the actual process of the present application.

[0085] The number of other material points in the material point field range is determined.

[0086] Determine the material point field radius δ, calculate the distance between the material point and the adjacent other material point based on the spatial coordinates of the material point; when the distance between the two is less than or equal to δ, it is a material point within the field range of the material point; loop until the number of all material points within the field of the material point is counted.

[0087] According to the near-field dynamics, the material point and other material points within a certain range have mutual interaction force, and the range is called "field", and its radius is represented by δ, i.e. the adjacent material points have interaction only when the distance is less than or equal to δ, and there is no interaction beyond this area.

[0088] Applying initial boundary conditions (including applying displacement boundary constraints, overburden gravity load and lateral tectonic stress), introducing scalar piecewise function, modifying near-field dynamic constitutive force function including:

[0089] The traditional near-field dynamic constitutive force function is:

[0090]

[0091] In the formula, μ represents a fracture parameter; s represents elongation; ξ represents the relative position of two material points in the initial reference configuration; η represents the relative displacement of two material points in the current configuration; ξ+η represents the relative position of two material points in the current configuration; || represents the modulus of a vector.

[0092] Material point x i and other material points x j within a certain range thereof

[0093]

[0094] In the formula, ο(x i ,x j ,t) represents the scalar piecewise function of the distance between the current material point x i and the adjacent material point x j in the preset time period t; c0 represents the microscopic elastic modulus of the surrounding rock; c p represents the microscopic elastic modulus of the surrounding rock softening; and c a represents the microscopic elastic modulus of the lining.

[0095] By introducing the scalar piecewise function, the modified near-field dynamic constitutive force function is as follows:

[0096]

[0097] In the formula, ο(x i ,x j ,t) represents the scalar piecewise function of the distance between the current material point x i and the adjacent material point x j in the preset time period t; μ represents a fracture parameter; s represents elongation; ξ represents the relative position of two material points in the initial reference configuration; η represents the relative displacement of two material points in the current configuration; ξ+η represents the relative position of two material points in the current configuration; || represents the modulus of a vector; and c represents the microscopic elastic modulus.

[0098] S4, using the central difference method to calculate and update the characteristic parameters of the material points, and realizing the tunnel excavation and support simulation through the material point passivation and activation technology.

[0099] Among them, the simulation of tunnel excavation and support through material point passivation and activation technology includes:

[0100] If the scalar piecewise function ο(x) i ,x j When ,t) is less than the preset threshold, the material point passivation effect is achieved, and the connection between material points inside the excavated area and the non-excavated area is weakened, so as to achieve the simulation effect of tunnel excavation disturbance.

[0101] If the scalar piecewise function ο(x) i ,x j When ,t) is greater than the preset threshold, the material point activation effect is achieved, and the connection between the material points inside the support area and the external rock mass is enhanced to simulate the support construction process.

[0102] If the scalar piecewise function ο(x) i ,x j When ,t) equals the preset threshold, it means that the interaction force between material points will not be changed.

[0103] To facilitate understanding of the above technical solutions of the present invention, the following provides a detailed description of how the present invention uses the central difference method to calculate and update the characteristic parameters of material points in actual processes, and uses material point passivation and activation technology to simulate tunnel excavation and support.

[0104] The velocity and position parameters of the material point are calculated and updated using the central difference method. Specifically, the central difference method is used to solve for the velocity and displacement of the material point at each time step. This is done when the acceleration of the material point at n steps is known. speed and displacement Then the velocity of the material point in step n+1 and displacement satisfy:

[0105]

[0106] In the formula, Δt represents the time step; and These represent the acceleration, velocity, and displacement of a point mass at step n, respectively. and These represent the velocity and displacement of the material point at step n+1, respectively.

[0107] After initial stress equilibrium is achieved, material point passivation and activation methods are used to simulate tunnel excavation and support.

[0108] like Figure 2 As shown, the material point passivation and activation method introduces a scalar piecewise function ο(x) into the material point constitutive force function. i ,xj The failure simulation of excavation and support effects is performed using ο(x). i ,x j When ,t) is less than 1, the material point passivation effect is exerted, that is, the effect of (0 < ο(x)) is weakened. i ,x j ,t)<1) or cut off (ο(x) i ,x j By controlling the connection between the material points within the excavated area and the non-excavated area (t) = 0, the stress release of the surrounding rock can be controlled, achieving the effect of simulating tunnel excavation disturbance. Conversely, when ο(x) = 0... i ,x j When ο(x) is greater than 1, the material point activation effect is achieved, that is, the connection between the material points inside the support area and between the material points and the external rock mass is enhanced, thus activating the lining and simulating the support construction process; when ο(x) is greater than 1, the material point activation effect is achieved, that is, the connection between the material points inside the support area and the external rock mass is enhanced, thus activating the lining and simulating the support construction process; i ,x j When ,t) equals 1, it indicates that the interaction forces between material points are not changed, and the initial state of the model is maintained, i.e., it does not belong to the excavation or support area. Among them, the near-field dynamic material point passivation and activation methods include:

[0109] Determine the excavation, softening, surrounding rock, and support areas; before tunnel excavation, the excavation area is softened, and the scalar function o(x) is used according to the piecewise scalar function. i ,x j ,t)=c p / c0; During tunnel excavation, the excavation area is completely passivated while the support area is "activated". According to the scalar piecewise function, the excavation area o(x) is then... i ,x j ,t)=0, support area o(x i ,x j ,t)=c a / c0).

[0110] S5. In the tunnel excavation and support simulation, the failure status of material point bonds in the support area is judged cyclically, and the cumulative support damage is calculated based on the failure status. The simulation results are optimized based on the cumulative support damage.

[0111] In the tunnel excavation and support simulation, the failure status of material point bonds in the support area is cyclically assessed, and the cumulative support damage is calculated based on the failure status, including:

[0112] In the simulation of tunnel excavation and support, the tensile strain between the current material point and the adjacent points is calculated, and the tensile strain is compared with the critical elongation.

[0113] If the tensile strain is greater than or equal to the critical elongation, it indicates that the material point key fails, the number of failed keys is counted, and the ratio of the number of failed keys to the initial number of complete keys is calculated to obtain the support cumulative damage value; if the tensile strain is less than the critical elongation, it indicates that the material point key does not fail.

[0114] In order to facilitate the understanding of the above technical solutions of the present application, the following will be described in detail in the actual process of the present application in the simulation of tunnel excavation and support, the failure condition of the material point key in the support area is judged, and the support cumulative damage is calculated based on the failure condition, and the simulation result is optimized according to the support cumulative damage.

[0115] The failure condition of the material point key in the support area is judged, the support cumulative damage is calculated, and the cycle is repeated until the specified calculation step is reached or the convergence condition is met, wherein the failure condition of the material point key in the support area is judged, and the support cumulative damage is calculated, including:

[0116] The tensile strain s between adjacent material points is calculated, and the size relationship between s and the critical elongation s0 is judged, when the tensile strain s of two material points is greater than or equal to s0, that is, the material point key fails; the number of failed keys is counted, and the support cumulative damage value is obtained by dividing the initial number of complete keys.

[0117] The failure condition of the material point key is determined by judging whether the tensile strain s of two material points exceeds the critical elongation s0, and the support cumulative damage is the ratio of the number of remaining complete keys to the initial number of keys after the material point key fails.

[0118] The following takes a tunnel excavation model test as a verification example to illustrate the rationality of the near-field dynamics material point passivation and activation method provided by the present application for simulating the support effect of tunnel excavation.

[0119] Referring to the geometric size and material parameters of the model test in the prior art, modeling analysis is carried out for the construction stage, and the disturbance deformation characteristics of the surrounding rock are analyzed to verify the effectiveness of the near-field dynamics material point passivation and activation method provided by the present application. According to the true triaxial geomechanical model test system, a two-dimensional strain model of 1m x 1m is established, and the horizontal load and vertical load borne by the model are both 0.5MPa, as shown in Figure 3 .

[0120] The model is modeled by uniform dispersion, and the multi-layer lining is simplified as a whole, the material point spacing (Δx) is 0.02m, the field radius δ = 3Δx, and the surrounding rock material parameters are specific gravity = 19kN / m 3, the elastic modulus = 0.0213 GPa, uniaxial compressive strength = 0.25 MPa, cohesion = 1.82 kPa, internal friction angle = 26.8 °, the initial support parameters of the lining material are elastic modulus = 0.42 GPa, uniaxial compressive strength = 0.43 MPa, tensile strength = 0.022 MPa, the secondary lining parameters of the lining material are elastic modulus = 0.66 GPa, uniaxial compressive strength = 0.67 MPa, tensile strength = 0.048 MPa, the model is first calculated for the stress equilibrium, and then simulated for the tunnel excavation.

[0121] It can be known from monitoring the change rule of the displacement of the material points at the lower boundary of the tunnel model with time steps that the initial stress field has reached a balanced state at about the 150th step, as shown in the figure. Figure 4 The displacement of the initial stress field is then cleared at the 200th step, the tunnel excavation and support are carried out at the 201th step, and the settlement deformation of the arch crown monitoring point is monitored, as shown in the figure. Figure 5 It can be seen that the excavation of the tunnel breaks the original balanced state, causes the sudden change of the settlement monitoring data of the arch crown, and tends to be stable after the 1200th step, and the overall growth trend is consistent with the model test results, which shows that the material point passivation and activation method proposed in the application effectively reproduces the disturbance characteristics of the surrounding rock in the tunnel excavation and support. In addition, it can be seen from the displacement cloud of the surrounding rock in the stable stage that the deformation distribution rule of the simulation result is basically consistent with the test result, and the surrounding rock deformation satisfies arch crown > arch shoulder > arch waist. However, the arch crown settlement monitored in the stable stage is about 20% higher than the model test result, and the reason for the error is related to the homogenization and isotropy assumption of the numerical simulation of the surrounding rock material, and the instantaneous loading used in the simulation instead of the staged loading in the model test. In summary, through comparison with the model test results, the simulation results are relatively good, which verifies the effectiveness of the material point passivation and activation method.

[0122] In summary, by means of the technical scheme of the application, the original material points in the excavation and support area are passivated and activated, the properties and coordinates of the material points are ensured to remain unchanged, so that the complex process of generating new material points and their property judgment and information storage is avoided, the calculation efficiency is effectively improved, the low efficiency problem of the traditional near-field dynamics method in simulating the dynamic construction process of excavation and support is overcome, and the scalar piecewise function is introduced to modify the constitutive force function, so that the method has simple format, clear physical meaning, and can more intuitively describe the mechanical behavior change of the excavation and support area.

[0123] The above only describes the preferred embodiments of the application and should not be used to limit the application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application should be included in the protection scope of the application.

Claims

1. A method of simulating the effect of tunnel excavation support by near-field dynamics of particle passivation and activation, characterized in that, The near-field dynamics particle passivation and activation method comprises: The near-field dynamics material parameters and fracture parameters are calculated based on the pre-acquired tunnel structural parameters, and a near-field dynamics constitutive force function is established according to the near-field dynamics material parameters and fracture parameters; The tunnel excavation and support region is determined according to the tunnel structural parameters, the excavation and support region is discretized into particles, and an excavation and support space coordinate matrix is generated according to the particle attribute classification; The field range of the particle is judged based on the excavation and support space coordinate matrix, a scalar segmented function is constructed according to the field range of the particle, the near-field dynamics constitutive force function is modified by using the scalar segmented function, and a modified near-field dynamics constitutive force function is obtained; The characteristic parameters of the particle are calculated and updated by using the central difference method, and the tunnel excavation and support simulation is realized by using the particle passivation and activation technology; The failure condition of the support region particle key is cyclically judged in the tunnel excavation and support simulation, the cumulative damage of the support is calculated based on the failure condition, and the simulation result is optimized according to the cumulative damage of the support. The tunnel excavation and support simulation is realized by using the particle passivation and activation technology, which comprises: The scalar piecewise function is the current material point x. i With neighboring material point x j The distance between them is a scalar piecewise function ο(x) within a preset time period t. i ,x j ,t); If the scalar piecewise function ο(x) i ,x j When ,t) is less than the preset threshold, the material point passivation effect is achieved, and the connection between material points inside the excavated area and the non-excavated area is weakened, so as to achieve the simulation effect of tunnel excavation disturbance. If the scalar section function 0(x i ,x j ,t) is greater than a preset threshold value, then the activation of the material points is realized, and the connection between the internal and external rock mass material points in the support area is enhanced to simulate the support construction process. If the scalar section function 0(x i ,x j ,t) is equal to a preset threshold value, it indicates that the force between the material points is not changed.

2. A method of simulating the effect of tunnel excavation support by near-field dynamics particle passivation and activation according to claim 1, characterized in that, The tunnel structural characteristic parameters comprise tunnel geometric dimensions, surrounding rock parameters and lining parameters; The near-field dynamics material parameters comprise a micro-elastic modulus and a critical elongation.

3. A method of simulating the effect of tunnel excavation support by means of near-field dynamics particle blunting and activation according to claim 2, characterized in that, The calculation formula of the micro-elastic modulus is: In the formula, c represents the micro-elastic modulus, E represents the elastic modulus of the material, h represents the thickness of the two-dimensional strain model, and δ represents the field radius. The calculation formula of the critical elongation is: In the formula, s0 represents the critical elongation, G0 represents the material fracture energy, κ represents the elastic parameter, and δ represents the field radius.

4. A method of simulating the effect of tunnel excavation support by means of near-field dynamics particle blunting and activation according to claim 1, characterized in that, The tunnel excavation and support region is discretized into particles according to the tunnel structural parameters, and an excavation and support space coordinate matrix is generated according to the particle attribute classification, which comprises: The region to be excavated and supported is determined based on the tunnel geometric dimensions and the surrounding rock parameters, and the size of the cubic lattice is determined, and the calculation region is covered by parallel arrangement of the cubic lattices; The center point of the cubic lattice is taken as the particle coordinate, and the region to which the particle coordinate belongs is judged; The particle coordinates belonging to the excavation region are stored in the excavation particle data set, and the particle coordinates belonging to the support region are stored in the support particle data set.

5. A method of simulating the effect of tunnel excavation support by means of near-field dynamics particle blunting and activation according to claim 1, characterized in that, The field range of the particle is judged based on the excavation and support space coordinate matrix, a scalar segmented function is constructed according to the field range of the particle, the near-field dynamics constitutive force function is modified by using the scalar segmented function, and a modified near-field dynamics constitutive force function is obtained, which comprises: The distance between the current particle and the adjacent particles is calculated based on the particle coordinate, and the number of other particles in the field range of the particle is judged; The distance between the current particle and the adjacent particles in the preset time period is established as a scalar segmented function according to the field range of the particle; The initial boundary conditions of the simulated tunnel excavation and support are applied, and the modified near-field dynamics constitutive force function is modified by using the scalar segmented function, and a modified near-field dynamics constitutive force function is obtained.

6. A method of simulating the effect of tunnel excavation support by near-field dynamics particle passivation and activation according to claim 5, characterized in that, The distance between the current material point and the adjacent material point is calculated based on the material point coordinate, and the number of other material points in the material point field range is determined, including: The material point field radius is determined, and the distance between the current material point and the adjacent material point is calculated based on the material point coordinate; If the distance between the current material point and the adjacent material point is less than or equal to the field radius, it indicates that the current material point and the adjacent material point have interaction force, and the current material point is a material point in the material point field range, and the number of all material points in the material point field range is counted. If the distance between the current material point and the adjacent material point is greater than the field radius, it indicates that the material point and the adjacent material point do not have interaction force.

7. A method of simulating the effect of tunnel excavation support by means of near-field dynamics particle passivation and activation according to claim 6, characterized in that, The expression of the distance between the current material point and the adjacent material point in the preset time period is a scalar segmented function: In the formula, o(x i ,x j ,t) represents the scalar piecewise function of the distance between the current material point x i and the adjacent material point x j in the preset time period t; c0 represents the microscopic elastic modulus of the surrounding rock; c p represents the microscopic elastic modulus of the surrounding rock softening; and c a represents the microscopic elastic modulus of the lining.

8. A method of simulating the effect of tunnel excavation support by near-field dynamics particle passivation and activation according to claim 7, characterized in that, The expression of the modified near-field dynamics constitutive force function is: where, o(x i ,x j ,t) represents the scalar-valued piecewise function of the distance between the current material point x i and the neighboring material point x j over the pre-set time period t; μ represents the fracture parameter; s represents the stretch; ξ represents the relative position of the two material points in the initial reference configuration; η represents the relative displacement of the two material points in the current configuration; ξ + η represents the relative position of the two material points in the current configuration; || represents the modulus of the vector; c represents the micro-elastic modulus.

9. A method of simulating the effect of tunnel excavation support by means of near-field dynamics particle blunting and activation according to claim 1, characterized in that, The failure condition of the support area material point key is judged in the tunnel excavation and support simulation, and the accumulated damage of the support is calculated based on the failure condition, including: The tensile strain between the current material point and the adjacent point is calculated in the tunnel excavation and support simulation, and the tensile strain is compared with the critical elongation rate; If the tensile strain is greater than or equal to the critical elongation rate, it indicates that the material point key has failed, the number of failed keys is counted, and the ratio of the number of failed keys to the number of initial complete keys is calculated to obtain the support accumulated damage value; If the tensile strain is less than the critical elongation rate, it indicates that the material point key has not failed.

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