Near-field dynamic material point passivation and activation method for simulating tunnel excavation supporting effect

Abstract

The invention discloses a near-field dynamic material point passivation and activation method for simulating a tunnel excavation supporting effect, and relates to the technical field of tunnel excavation, the near-field dynamic material point passivation and activation method comprises the following steps: establishing a near-field dynamic constitutive force function according to near-field dynamic material parameters and fracture parameters; determining a tunnel excavation and support area according to tunnel structural parameters, discretizing the excavation and support area into material points, and generating an excavation and support space coordinate matrix according to attribute classification of the material points; correcting the near-field dynamic constitutive force function by using the scalar piecewise function to obtain a corrected near-field dynamic constitutive force function; and tunnel excavation and support simulation is realized through a material point passivation and activation technology. According to the method, the original material points of the excavation and support area are passivated and activated to ensure that the attributes and coordinates of the material points remain unchanged, so that the complex process of regenerating new material points and attribute judgment and information storage thereof is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel excavation, and in particular to a near-field dynamic material point passivation and activation method for simulating tunnel excavation support. Background Art

[0002] As an emerging theory of non-local action, peridynamics discretizes the solution area into material points with certain physical and mechanical information, and characterizes the deformation and damage of materials based on the spatial position changes of material points and the interaction between adjacent material points. Because it uses the integral form of the motion equation, it overcomes the singularity problem existing in the traditional numerical method for solving discontinuous problems, and in theory, there is no special requirement for the size of the non-local action domain, so that peridynamics can describe a series of mechanical behaviors from continuous to discontinuous, from microscopic to macroscopic, and is particularly suitable for solving the damage and destruction problems of solid materials. The above-mentioned non-local action idea enables peridynamics to better reproduce the random evolution process of crack damage in solid materials, making it widely concerned in the study of damage evolution of tunnel surrounding rock and lining.

[0003] The stress and deformation of tunnel structures are often closely related to their construction process. The construction process of tunnel engineering mainly includes two parts: excavation and support. Among them, tunnel excavation unloading is one of the main reasons for the instability of surrounding rock and the induction of various geological disasters; the role of tunnel support is to resist the continuous deformation of surrounding rock, put the surrounding rock in a multiaxial stress state, and provide support force for the surrounding rock to maintain stability. Therefore, whether the tunnel excavation and support process can be accurately simulated is crucial to exploring the evolution mechanism of crack damage in soft rock tunnel lining. However, due to the lack of near-field dynamics methods that can reflect the dynamic change process of tunnel excavation and support, it is impossible to effectively reveal the evolution mechanism of tunnel excavation disturbance and support bearing failure.

[0004] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention

[0005] In view of the problems in the related art, the present invention proposes a near-field dynamic material point passivation and activation method that simulates the tunnel excavation support effect to overcome the above-mentioned technical problems existing in the existing related art.

[0006] To this end, the specific technical solution adopted by the present invention is as follows:

[0007] A peridynamic material point passivation and activation method for simulating tunnel excavation support, the peridynamic material point passivation and activation method comprising:

[0008] The peridynamic material parameters and fracture parameters are calculated based on the pre-collected tunnel structural parameters, and the peridynamic constitutive force function is established according to the peridynamic material parameters and fracture parameters;

[0009] Determine the tunnel excavation and support areas according to the tunnel structural parameters, discretize the excavation and support areas into material points, and generate the excavation and support space coordinate matrix according to the material point attribute classification;

[0010] The domain range of the material point is determined based on the excavation and support space coordinate matrix, and a scalar piecewise function is constructed according to the domain range of the material point. The peridynamic constitutive force function is corrected by using the scalar piecewise function to obtain a corrected peridynamic constitutive force function.

[0011] The central difference method is used to calculate and update the characteristic parameters of material points, and the tunnel excavation and support simulation is realized through the material point passivation and activation technology;

[0012] In the tunnel excavation and support simulation, the failure conditions of the material point bonds in the support area are cyclically judged, and the cumulative damage of the support is calculated based on the failure conditions. The simulation results are optimized according to the cumulative damage of the support.

[0013] Preferably, the structural characteristic parameters of the tunnel include tunnel geometric dimensions, surrounding rock parameters and lining parameters; the peridynamic 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; δ represents the field radius;

[0017] The calculation formula of critical elongation is:

[0018]

[0019] Where s0 represents the critical elongation; G0 represents the material fracture energy; κ represents the elastic parameter; δ represents the field radius.

[0020] Preferably, determining the tunnel excavation and support area according to the tunnel structural parameters, discretizing the excavation and support area into material points, and generating the excavation and support space coordinate matrix according to the material point attribute classification includes:

[0021] Based on the geometric dimensions of the tunnel and the parameters of the surrounding rock, the area to be excavated and supported is determined, and the size of the cube lattice is determined. The calculation area is covered by arranging the cube lattice in parallel.

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

[0023] The coordinates of the material points belonging to the excavation area are stored in the excavation material point data set, and the coordinates of the material points belonging to the support area are stored in the support material point data set.

[0024] Preferably, the domain range of the material point is determined based on the excavation and support space coordinate matrix, and a scalar piecewise function is constructed according to the domain range of the material point. The peridynamic constitutive force function is corrected by using the scalar piecewise function, and the corrected peridynamic constitutive force function includes:

[0025] Calculate the distance between the current material point and the adjacent material points based on the material point coordinates, and determine the number of other material points within the material point area;

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

[0027] The initial boundary conditions simulating tunnel excavation and support are applied, and the modified peridynamic constitutive force function is modified by using a scalar piecewise function to obtain the modified peridynamic constitutive force function.

[0028] Preferably, calculating the distance between the current material point and the adjacent material point based on the material point coordinates, and determining the number of other material points within the material point area includes:

[0029] Determine the radius of the material point area, and calculate the distance between the current material point and the adjacent material point based on 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 means that there is an interaction force between the current material point and the adjacent material point, and the current material point is a material point within the material point domain, and the number of all material points within the material point domain is counted;

[0031] If the distance between the current material point and the adjacent material point is greater than the domain radius, it means 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 the preset time period is:

[0033]

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

[0035] Preferably, the expression of the modified peridynamic constitutive force function is:

[0036]

[0037] In the formula, ο(x i ,x j ,t) represents the current material point x i and the adjacent material point x j The distance between the two material points in the preset time period t is a scalar piecewise function; μ represents the fracture parameter; s represents the elongation; 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.

[0038] Preferably, the tunnel excavation and support simulation is realized by material point passivation and activation technology, including:

[0039] If the scalar piecewise function ο(x i ,x j ,t) is less than the preset threshold, the material point passivation effect is realized, and the connection between the material points inside the excavation area and the non-excavation area is weakened to achieve the tunnel excavation disturbance simulation effect;

[0040] If the scalar piecewise function ο(x i ,x j ,t) is greater than the preset threshold, the material point activation effect is achieved, and the connection between the internal and external rock material points in the support area is enhanced to simulate the support construction process;

[0041] If the scalar piecewise function ο(x i ,x j ,t) is equal to the preset threshold, it means that there is no change in the force between material points.

[0042] Preferably, cyclically judging the failure conditions of material point bonds in the support area in the tunnel excavation and support simulation, and calculating the support cumulative damage based on the failure conditions includes:

[0043] Calculate the tensile strain between the current material point and the adjacent points in tunnel excavation and support simulation, and compare the tensile strain with the critical elongation;

[0044] If the tensile strain is greater than or equal to the critical elongation, it means that the material point bond has failed. The number of failed bonds is counted, and the ratio of the number of failed bonds to the initial number of intact bonds is calculated to obtain the cumulative damage value of the support. If the tensile strain is less than the critical elongation, it means that the material point bond has not failed.

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

[0046] The present invention passivates and activates the original material points in the excavation and support areas to ensure that the properties and coordinates of the material points remain unchanged, thereby avoiding the complex process of regenerating new material points and judging their properties and storing information. This method effectively improves the calculation efficiency and overcomes the low efficiency of traditional peri-field dynamics methods in simulating the dynamic construction process of excavation and support. The constitutive force function is corrected by introducing a scalar piecewise function. This method has a simple format and clear physical meaning, and can more intuitively describe the changes in the mechanical behavior of the excavation and support areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 is a flow chart of a method for passivation and activation of peridynamic material points for simulating tunnel excavation support according to an embodiment of the present invention;

[0049] Figure 2 is a schematic diagram of a peridynamic material point passivation and activation method for simulating tunnel excavation support according to an embodiment of the present invention;

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

[0051] Figure 4 This is a diagram comparing displacements of measuring points in a stress balance stage in a near-field dynamic material point passivation and activation method for simulating tunnel excavation support according to an embodiment of the present invention;

[0052] Figure 5 This is a diagram comparing the crown measurement points in the excavation stage of a near-field dynamic material point passivation and activation method for simulating tunnel excavation support according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments. They can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in this field should be able to understand other possible implementation methods and advantages of the present invention.

[0054] According to an embodiment of the present invention, a peridynamic material point passivation and activation method for simulating tunnel excavation support is provided.

[0055] The present invention is further described with reference to the accompanying drawings and specific embodiments. Figure 1 As shown, according to the peridynamic material point passivation and activation method for simulating tunnel excavation support according to an embodiment of the present invention, the peridynamic material point passivation and activation method comprises:

[0056] S1. Calculate the peridynamic material parameters and fracture parameters based on the pre-collected tunnel structural parameters, and establish the peridynamic constitutive force function according to the peridynamic material parameters and fracture parameters.

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

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

[0059]

[0060] Where 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.

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

[0062]

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

[0064] S2. Determine the tunnel excavation and support area according to the tunnel structural parameters, discretize the excavation and support area into material points, and generate the excavation and support space coordinate matrix according to the material point attribute classification.

[0065] Among them, the tunnel excavation and support areas are determined according to the tunnel structural parameters, the excavation and support areas are discretized into material points, and the excavation and support space coordinate matrix is ​​generated according to the material point attribute classification, including:

[0066] Based on the geometric dimensions of the tunnel and the parameters of the surrounding rock, the area to be excavated and supported is determined, and the size of the cube lattice is determined. The calculation area is covered by arranging the cube lattice in parallel.

[0067] Take the center point of the cubic lattice as the material point coordinate and determine the region to which the material point coordinate belongs;

[0068] The coordinates of the material points belonging to the excavation area are stored in the excavation material point data set, and the coordinates of the material points belonging to the support area are stored in the support material point data set.

[0069] In order to facilitate understanding of the above technical scheme of the present invention, the present invention will be described in detail below in the actual process of determining the tunnel excavation and support areas according to the tunnel structural parameters, discretizing the excavation and support areas into material points, and generating the excavation and support space coordinate matrix according to the material point attribute classification.

[0070] Determine the area to be excavated and the support area, discretize the calculation area, and generate the surrounding rock and support space coordinate matrix according to the material point attribute classification, including:

[0071] Determine the area to be excavated and the support area based on the geometric dimensions of the tunnel and surrounding rock.

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

[0073] The discrete calculation area includes: determining the basic size of the cubic lattice; arranging these lattices in parallel, covering the calculation area with the discretized lattice, and each lattice center is the coordinate of the spatial material point. It is judged whether its spatial distribution range belongs to the excavation or support area, so as to classify and count its coordinate matrix.

[0074] Generating the surrounding rock and support spatial coordinate matrix based on the material point attribute classification means that the material point spatial position (material point coordinates) in the excavation or support area is determined, and the material point coordinates belonging to the excavation area are stored in the excavation material point data set, and those belonging to the support area are stored in another data set. From the perspective of programming language, a data set is an array, such as coordinates [n][4].

[0075] S3. Determine the domain range of the material point based on the excavation and support space coordinate matrix, and construct a scalar piecewise function according to the domain range of the material point. Use the scalar piecewise function to correct the peridynamic constitutive force function to obtain a corrected peridynamic constitutive force function.

[0076] Among them, the domain range of the material point is determined based on the excavation and support space 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 correct the peridynamic constitutive force function, and the corrected peridynamic constitutive force function includes:

[0077] Based on the material point coordinates, the distance between the current material point and the adjacent material points is calculated, and the number of other material points within the material point area is determined.

[0078] Among them, 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 within the material point area is determined, including:

[0079] Determine the radius of the material point area, 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 domain radius, it means that there is an interaction force between the current material point and the adjacent material point, and the current material point is a material point within the material point domain, and the number of all material points within the material point domain is counted;

[0081] If the distance between the current material point and the adjacent material point is greater than the domain radius, it means that there is no interaction force between the material point and the adjacent material point.

[0082] 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 points in a preset time period is established.

[0083] The initial boundary conditions simulating tunnel excavation and support are applied, and the modified peridynamic constitutive force function is modified by using a scalar piecewise function to obtain the modified peridynamic constitutive force function.

[0084] In order to facilitate understanding of the above technical scheme of the present invention, the present invention in the actual process determines the domain range of material points based on the excavation and support space coordinate matrix, constructs a scalar piecewise function according to the domain range of material points, and uses the scalar piecewise function to correct the peridynamic constitutive force function to obtain the corrected peridynamic constitutive force function. This is described in detail below.

[0085] Among them, the number of other material points within the range of the material point domain is determined as follows:

[0086] Determine the radius δ of the material point domain, and calculate the distance between the material point and other adjacent material points 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 domain of the material point; repeat the judgment until the number of all material points in the domain of the material point is counted.

[0087] According to perifield dynamics, there is an interaction force between material points and other material points within a certain range. This range is called a "field" and its radius is represented by δ. That is, there is interaction between adjacent material points only when the distance between them is less than or equal to δ, and there is no interaction beyond this area.

[0088] Apply initial boundary conditions (including displacement boundary constraints, overburden gravity loads and lateral tectonic stresses), introduce scalar piecewise functions, and modify the peridynamic constitutive force function to include:

[0089] The traditional peridynamic constitutive force function is:

[0090]

[0091] Wherein, μ represents the fracture parameter; s represents the elongation; 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.

[0092] Material point x i With other material points x within a certain range j The scalar piecewise function at time t is as follows:

[0093]

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

[0095] By introducing the scalar piecewise function, the modified peridynamic constitutive force function can be obtained as follows:

[0096]

[0097] In the formula, ο(x i ,x j ,t) represents the current material point x i and the adjacent material point x j The distance between the two material points in the preset time period t is a scalar piecewise function; μ represents the fracture parameter; s represents the elongation; 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.

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

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

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

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

[0102] If the scalar piecewise function ο(x i ,x j ,t) is equal to the preset threshold, it means that there is no change in the force between material points.

[0103] In order to facilitate understanding of the above technical solution of the present invention, the following is a detailed description of the present invention in the actual process of using the central difference method to calculate and update the characteristic parameters of material points, and realizing tunnel excavation and support simulation through material point passivation and activation technology.

[0104] The velocity and position of the material point are calculated and updated by the central difference method. The central difference method is used to calculate and update the velocity and position of the material point at each time step. speed and displacement Then the speed of the material point in step n+1 is and displacement satisfy:

[0105]

[0106]

[0107] In the formula, Δt represents the time step; and They represent the acceleration, velocity and displacement of the material point in n steps respectively; and They represent the velocity and displacement of the material point in the n+1 step respectively.

[0108] After the initial ground stress is balanced, the material point passivation and activation method is used to realize the tunnel excavation and support simulation.

[0109] like Figure 2 As shown in the figure, the material point passivation and activation method is to introduce a scalar piecewise function ο(x i ,xj ,t) to simulate the excavation and support effects. i ,x j ,t) is less than 1, the material point passivation effect is exerted, that is, the (0<ο(x i ,x j ,t)<1) or cut off (ο(x i ,x j ,t)=0) the connection between the material points inside the excavation area and the non-excavation area, realize the controlled release of surrounding rock stress, and achieve the simulation effect of tunnel excavation disturbance. On the contrary, when ο(x i ,x j When ο(x t) 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, and the lining activation is achieved to simulate the support construction process; when ο(x i ,x j , t) is equal to 1, it means that the forces between material points are not changed, and the initial state of the model is maintained, that is, it does not belong to the excavation or support area. Among them, the passivation and activation methods of peridynamic material points include:

[0110] Determine the excavation, softening, surrounding rock and support areas; before tunnel excavation, soften the excavation area, and then calculate the scalar function o(x i ,x j ,t)=c p / c0; When tunneling, the excavation area is completely passivated and the support area is "activated". According to the scalar piecewise function, the excavation area o(x i ,x j ,t)=0, support area o(x i ,x j ,t)=c a / c0).

[0111] S5. In the tunnel excavation and support simulation, the failure conditions of the material point bonds in the support area are cyclically determined, and the cumulative damage of the support is calculated based on the failure conditions, and the simulation results are optimized according to the cumulative damage of the support.

[0112] Among them, the failure of material point bonds in the support area is cyclically judged in the tunnel excavation and support simulation, and the cumulative damage of the support is calculated based on the failure situation, including:

[0113] Calculate the tensile strain between the current material point and the adjacent points in tunnel excavation and support simulation, and compare the tensile strain with the critical elongation;

[0114] If the tensile strain is greater than or equal to the critical elongation, it means that the material point bond has failed. The number of failed bonds is counted, and the ratio of the number of failed bonds to the initial number of intact bonds is calculated to obtain the cumulative damage value of the support. If the tensile strain is less than the critical elongation, it means that the material point bond has not failed.

[0115] In order to facilitate understanding of the above technical scheme of the present invention, the present invention will be described in detail below in the actual process of cyclically judging the failure conditions of material point keys in the support area in tunnel excavation and support simulation, and calculating the support cumulative damage based on the failure conditions, and optimizing the simulation results based on the support cumulative damage.

[0116] Determine the failure of material point bonds in the support area, calculate the cumulative damage of the support, and repeat the cycle until the specified calculation step is reached or the convergence condition is met. Determine the failure of material point bonds in the support area and calculate the cumulative damage of the support, including:

[0117] Calculate the tensile strain s between adjacent material points and determine its relationship with the critical elongation s0. When the tensile strain s of two material points is ≥ s0, the material point bond fails. Count the number of failed bonds and divide it by the initial number of intact bonds to obtain the cumulative damage value of the support.

[0118] The failure condition of the material point bond is determined by judging whether the tensile strain s of the two material points exceeds its critical elongation s0. The cumulative damage of the support is the ratio of the number of remaining complete bonds to the initial number of bonds after the material point bond breaks.

[0119] The following is a tunnel excavation model test as a verification example to illustrate the rationality of the near-field dynamic material point passivation and activation method for simulating the tunnel excavation support effect provided by the present invention.

[0120] Referring to the geometric dimensions and material parameters of the model test in the existing literature, a modeling analysis is carried out for the construction stage, and the effectiveness of the peridynamic material point passivation and activation method proposed in this invention is verified by analyzing the deformation characteristics of the surrounding rock disturbance. According to the true triaxial geomechanical model test system, a 1m×1m two-dimensional strain model is established. The horizontal and vertical loads borne by the model are both 0.5MPa. Figure 3 shown.

[0121] The model is modeled in a uniform discrete manner, and the multi-layer lining is simplified into a whole. The material point spacing (Δx) is 0.02m, the field radius δ=3Δx, and the surrounding rock material parameters are gravity=19kN / m 3, 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, and 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 first performs ground stress balance calculation and then performs tunnel excavation simulation.

[0122] By monitoring the displacement of the boundary material points in the tunnel model over time, it can be seen that the initial stress field has reached a balanced state around the 150th step, as shown in Figure 4 Then, at step 200, the initial stress field displacement is cleared, and at step 201, tunnel excavation and support are carried out, and the settlement deformation of the arch crown measuring point is monitored, as shown in Figure 5 As shown. It can be seen that the excavation of the tunnel broke the original equilibrium state, causing a sudden change in the monitoring data of the vault settlement, and it tended to be stable after 1200 steps. The overall growth trend was consistent with the model test results, indicating that the material point passivation and activation method proposed in the present invention effectively reproduced the disturbance characteristics of tunnel excavation and supporting surrounding rock. In addition, it can be seen from the surrounding rock displacement cloud map in the stable stage that the deformation distribution law of the simulation results is basically consistent with the test results, and the surrounding rock deformation satisfies the vault> spandrel> waist. However, the vault settlement monitored by the simulation in the stable stage is about 20% higher than the model test results. The reason for this error is related to the homogenization of the surrounding rock material in the numerical simulation, the assumption of isotropy, and the use of instantaneous loading in the simulation instead of graded loading in the model test. In short, by comparing with the model test results, the simulation results are relatively consistent, verifying the effectiveness of the material point passivation and activation method.

[0123] In summary, with the help of the above-mentioned technical scheme of the present invention, the present invention passivates and activates the original material points in the excavation and support areas to ensure that the properties and coordinates of the material points remain unchanged, thereby avoiding the complex process of regenerating new material points and their property judgment and information storage. This method effectively improves the calculation efficiency and overcomes the low efficiency of traditional near-field dynamics methods in simulating the dynamic construction process of excavation and support. The constitutive force function is corrected by introducing a scalar piecewise function. This method has a simple format and clear physical meaning, and can more intuitively describe the changes in the mechanical behavior of the excavation and support areas.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for passivation and activation of peridynamic material points simulating tunnel excavation support, characterized in that: The peridynamic material point passivation and activation method comprises: The peridynamic material parameters and fracture parameters are calculated based on the pre-collected tunnel structural parameters, and the peridynamic constitutive force function is established according to the peridynamic material parameters and fracture parameters; Determine the tunnel excavation and support areas according to the tunnel structural parameters, discretize the excavation and support areas into material points, and generate the excavation and support space coordinate matrix according to the material point attribute classification; The domain range of the material point is determined based on the excavation and support space coordinate matrix, and a scalar piecewise function is constructed according to the domain range of the material point. The peridynamic constitutive force function is corrected by using the scalar piecewise function to obtain a corrected peridynamic constitutive force function. The central difference method is used to calculate and update the characteristic parameters of material points, and the tunnel excavation and support simulation is realized through the material point passivation and activation technology; In the tunnel excavation and support simulation, the failure conditions of the material point bonds in the support area are cyclically judged, and the cumulative damage of the support is calculated based on the failure conditions. The simulation results are optimized according to the cumulative damage of the support.

2. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 1, characterized in that: The tunnel structural characteristic parameters include tunnel geometric dimensions, surrounding rock parameters and lining parameters; The peridynamic material parameters include micro elastic modulus and critical elongation.

3. A peridynamic material point passivation and activation method for simulating tunnel excavation support 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; δ represents the field radius; The calculation formula of the critical elongation is: Where s0 represents the critical elongation; G0 represents the material fracture energy; κ represents the elastic parameter; δ represents the field radius.

4. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 3, characterized in that: The step of determining the tunnel excavation and support area according to the tunnel structural parameters, discretizing the excavation and support area into material points, and generating the excavation and support space coordinate matrix according to the material point attribute classification includes: Based on the geometric dimensions of the tunnel and the parameters of the surrounding rock, the area to be excavated and supported is determined, and the size of the cube lattice is determined. The calculation area is covered by arranging the cube lattice in parallel. Take the center point of the cubic lattice as the material point coordinate and determine the region to which the material point coordinate belongs; The coordinates of the material points belonging to the excavation area are stored in the excavation material point data set, and the coordinates of the material points belonging to the support area are stored in the support material point data set.

5. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 4, characterized in that: The method of judging the domain range of the material point based on the excavation and support space coordinate matrix, constructing a scalar piecewise function according to the domain range of the material point, and using the scalar piecewise function to correct the peridynamic constitutive force function, obtains a corrected peridynamic constitutive force function including: Calculate the distance between the current material point and the adjacent material points based on the material point coordinates, and determine the number of other material points within the material point area; According to the range of the material point domain, a scalar piecewise function of the distance between the current material point and the adjacent material points in a preset time period is established; The initial boundary conditions simulating tunnel excavation and support are applied, and the modified peridynamic constitutive force function is modified by using a scalar piecewise function to obtain the modified peridynamic constitutive force function.

6. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 5, characterized in that: The calculation of the distance between the current material point and the adjacent material point based on the material point coordinates and the determination of the number of other material points within the material point area include: Determine the radius of the material point area, and calculate the distance between the current material point and the adjacent material point based on the material point coordinates; If the distance between the current material point and the adjacent material point is less than or equal to the domain radius, it means that there is an interaction force between the current material point and the adjacent material point, and the current material point is a material point within the material point domain, and the number of all material points within the material point domain is counted; If the distance between the current material point and the adjacent material point is greater than the domain radius, it means that there is no interaction force between the material point and the adjacent material point.

7. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 6, characterized in that: The expression of the scalar piecewise function of the distance between the current material point and the adjacent material point in the preset time period is: In the formula, ο(x i ,x j ,t) represents the current material point x i and the adjacent material point x j The distance between the two is a scalar piecewise function in a preset time period t; c0 represents the micro elastic modulus of the surrounding rock; c p The micro elastic modulus indicating the softening of the surrounding rock; c a Represents the micro elastic modulus of the lining.

8. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 7, characterized in that: The expression of the modified peridynamic constitutive force function is: In the formula, ο(x i ,x j ,t) represents the current material point x i and the adjacent material point x j The distance between the two material points in the preset time period t is a scalar piecewise function; μ represents the fracture parameter; s represents the elongation; 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.

9. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 8, characterized in that: The tunnel excavation and support simulation realized by material point passivation and activation technology includes: If the scalar piecewise function ο(x i ,x j ,t) is less than the preset threshold, the material point passivation effect is achieved, and the connection between the material points inside the excavation area and the non-excavation area is weakened to achieve the tunnel excavation disturbance simulation effect; If the scalar piecewise function ο(x i ,x j ,t) is greater than the preset threshold, the material point activation effect is achieved, and the connection between the internal and external rock material points in the support area is enhanced to simulate the support construction process; If the scalar piecewise function ο(x i ,x j ,t) is equal to the preset threshold, it means that there is no change in the force between material points.

10. A peridynamic material point passivation and activation method for simulating tunnel excavation support according to claim 9, characterized in that: The method of cyclically judging the failure conditions of material point bonds in the support area in the tunnel excavation and support simulation, and calculating the support cumulative damage based on the failure conditions includes: Calculate the tensile strain between the current material point and the adjacent points in tunnel excavation and support simulation, and compare the tensile strain with the critical elongation; If the tensile strain is greater than or equal to the critical elongation, it means that the material point bond has failed. The number of failed bonds is counted, and the ratio of the number of failed bonds to the initial number of intact bonds is calculated to obtain the cumulative damage value of the support. If the tensile strain is less than the critical elongation, it means that the material point bond has not failed.

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