Method and system for acquiring deformation stress increment of extremely-thin lamellar weak surrounding rock

Abstract

The invention discloses a method and a system for acquiring deformation stress increment of extremely-thin lamellar weak surrounding rock. Relates to the technical field of tunnel engineering. Obtaining a strain increment matrix of the extremely-thin laminar weak surrounding rock under the overall coordinate system, calculating a stress tensor matrix of deformation of the extremely-thin laminar weak surrounding rock under the overall coordinate system by combining the rotation matrix and the element stiffness matrix under an elastic assumption theory, and calculating a deformation stress increment according to the stress tensor matrix after characteristic correction; according to the scheme, the method is improved on the basis of a traditional extremely-thin lamellar surrounding rock mechanical property simulation technology, and a stress increment matrix of deformation of the extremely-thin lamellar weak surrounding rock under an overall coordinate system is calculated on the basis of a strain increment matrix, a rotation matrix and an element stiffness matrix under an elastic assumption theory; after the characteristics of the stress increment matrix are corrected, the deformation stress increment is calculated, the stress deformation characteristics of the extremely-thin lamellar weak surrounding rock are accurately and reasonably described, and the engineering analysis efficiency of the extremely-thin lamellar weak surrounding rock is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering, and in particular to a method and system for obtaining deformation stress increments of extremely thin layered weak surrounding rock. Background Art

[0002] In tunnel engineering and underground cavern construction, accurate mechanical description of extremely thin layered surrounding rock is a prerequisite for implementing scientific support design. This type of rock mass has significant heterogeneity and anisotropy, and its mechanical behavior is controlled by multiple coupled factors, including the geometric distribution of interlayer structural planes, the mechanical properties of the rock matrix, and the spacing between structural planes. Currently, the numerical simulation methods commonly used both domestically and internationally mainly include the following four categories: The discrete element model (DEM) simulates layered structures by discretizing granular elements. Although it can characterize rock mass fragmentation, it suffers from low computational efficiency and high complexity of the contact determination algorithm. This makes numerical convergence difficult, especially under conditions of large deformation in weak surrounding rock. The contact surface model uses explicit interface elements to describe interlayer slip, but it has the disadvantage of insufficient sensitivity to the structural plane spacing parameter and cannot accurately reflect the progressive failure process of thin rock masses (layer thickness < 10 cm); Although the ubiquitous joint model can take into account the influence of multiple groups of structural planes, its constitutive relationship does not reasonably introduce the yield criterion of the rock matrix, resulting in an oversimplification of the rock failure mechanism under high stress conditions. Although the transversely isotropic ubiquitous joint model has partially solved the problem of material anisotropy, the following technical bottlenecks still exist: the stiffness matrix has not established the mechanical mechanism of normal / tangential stiffness anisotropy; the equivalent continuous medium transformation criterion considering the spacing and layer thickness of the structural planes has not been constructed; and the multi-scale coupling of the elastic-plastic constitutive law of the rock matrix and the plastic evolution of the structural planes has not been achieved.

[0003] These methods exhibit significant limitations when applied to extremely thin, weak surrounding rock. First, existing models generally assume isotropic stiffness, which fundamentally conflicts with the actual normal-tangential stiffness disparity found in thin rock masses. Second, the spacing parameters for structural planes are often averaged, ignoring the characteristic spacing gradient distribution characteristic of thin-layered structures. Third, existing algorithms fail to establish a co-evolution equation for the plastic yielding of the rock matrix and structural planes, resulting in distorted numerical representations of the progressive failure process of the surrounding rock. These issues directly lead to conservative or insufficient support parameter design, which has caused numerous engineering accidents such as initial support encroachment and face instability in deep tunnels with weak surrounding rock. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: for the traditional method of simulating the mechanical properties of ultra-thin layered surrounding rocks, in the application of ultra-thin layered weak surrounding rocks, it exposes significant limitations such as ignoring the spacing gradient distribution law unique to thin layered structures, low calculation efficiency and high difficulty; the purpose of the present invention is to provide a method and system for obtaining deformation stress increments of ultra-thin layered weak surrounding rocks, and to improve the method on the basis of traditional ultra-thin layered weak surrounding rock mechanical properties simulation technology. Based on the strain increment matrix of ultra-thin layered weak surrounding rocks, combined with the rotation matrix and the unit stiffness matrix, under the elastic assumption theory, the stress tensor matrix of the deformation of the ultra-thin layered weak surrounding rocks in the overall coordinate system is calculated; after correcting the characteristics of the stress tensor matrix, the deformation stress increment is calculated, and the stress and deformation characteristics of the ultra-thin layered weak surrounding rocks are accurately and reasonably described, thereby improving the engineering analysis efficiency of the ultra-thin layered weak surrounding rocks.

[0005] The present invention is achieved through the following technical solutions: This solution provides a method for obtaining deformation stress increments of extremely thin layered weak surrounding rock, wherein the extremely thin layered weak surrounding rock is a weak surrounding rock containing a set of extremely thin layered structural surfaces and meeting the Mohr Coulomb strength criterion. The method comprises: Construct a global coordinate system and collect structural surface information of extremely thin layered weak surrounding rock in the global coordinate system; Construct the local coordinate system and the rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; Describe the stiffness parameters of extremely thin layered weak surrounding rock in the local coordinate system, and construct the element stiffness matrix based on the stiffness parameters; Obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the element stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock in the global coordinate system is deformed; The stress tensor matrix is ​​modified according to its plastic properties and the actual deformation stress increment matrix is ​​calculated.

[0006] A further optimization solution is that the structural surface information includes: Unit normal vector and normal spacing of the structural surface in the global coordinate system l j , normal stiffness k n and shear stiffness k s ; Cohesion of structural surfaces c j , internal friction angle φ j and dilatancy angle Ψ j ; Young's elastic modulus of rock matrix Eso , Poisson's ratio v , cohesion c , internal friction angle φ and dilatancy angle Ψ .

[0007] A further optimization scheme is to construct a local coordinate system and a rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; including the following method: A local coordinate system that satisfies the right-hand screw rule is constructed with the normal direction of the structural surface as the z' axis of the local coordinate system and the direction of the structural surface as the y' axis of the local coordinate system; wherein the z' axis has direction A as the positive direction, and the direction A is the direction in which the angle between the z' axis and the z axis of the spatial global coordinate system is ≤90°; the x' axis of the local coordinate system has direction B as the positive direction, and the direction B is the direction in which the angle between the x' axis and the z axis of the global coordinate system is ≥90°; According to the unit normal vector of the structural surface in the global coordinate system, the unit direction vector of the local coordinate system in the global coordinate system is calculated; According to the unit direction vector of the local coordinate system under the global coordinate system, a rotation matrix from the global coordinate system to the local coordinate system is constructed.

[0008] A further optimization scheme is to describe the stiffness parameters of the extremely thin layered weak surrounding rock in the local coordinate system; including the following method: The stiffness parameters of the extremely thin layered weak surrounding rock are described using the transversely isotropic material method. The stiffness parameters include: Young's elastic modulus perpendicular to the structural surface , Young's elastic modulus parallel to the structural surface E' = E so , Poisson's ratio of the x' axis and the y' axis in the structural plane , Poisson's ratio in the x', y' and z' directions within the structural plane v'=v , and the shear modulus parallel to the plane ; .

[0009] A further optimization scheme is that the unit stiffness matrix is ​​constructed based on the stiffness parameters, including the following method: The first coefficient is calculated according to the following formula M and the second coefficient n : ; ; Based on the first coefficient M and the second coefficient n Construct the element stiffness matrix K: .

[0010] A further optimization scheme is to obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the unit stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock in the global coordinate system is deformed; including the following methods: The strain increment matrix in the global coordinate system is expressed as a column vector, and the stress increment matrix in the elastic assumption and local coordinate system is obtained based on the elastic assumption theory and the element stiffness matrix. Based on the rotation matrix, the stress increment matrix under the elastic assumption and the local coordinate system is converted into the stress increment matrix under the elastic assumption and the global coordinate system; The existing stress tensor matrix in the global coordinate system is preset, and combined with the existing stress tensor matrix and the stress increment matrix under the elastic assumption and the global coordinate system, the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock undergoes deformation in the global coordinate system is obtained.

[0011] A further optimization scheme is that the method of correcting the plastic characteristics of the stress tensor matrix includes: Convert the stress tensor matrix into the expression of principal stress space to calculate the yield function value of the substrate f s ; When the substrate yield function value f s When ≤0, no plastic correction is performed on the stress tensor matrix; when the yield function value of the substrate is f s When >0, the stress tensor matrix is ​​corrected for substrate plasticity; The yield function value of the structural surface is calculated based on the stress tensor matrix in the local coordinate system after the plastic properties of the substrate are corrected. f sj ; When the structural surface yield function value f sj When ≤0, no plastic correction is performed on the stress tensor matrix; when the yield function value of the structural surface f sj When >0, the stress tensor matrix is ​​plastically corrected.

[0012] A further optimization scheme is that the method of correcting the plastic characteristics of the stress tensor matrix includes: Construct the substrate strain auxiliary correction matrix in the principal stress space, convert the substrate strain auxiliary correction matrix into the expression of the local coordinate system and into the column vector form, calculate the substrate stress auxiliary correction matrix in the local coordinate system based on the element stiffness matrix, and then convert the substrate stress auxiliary correction matrix in the local coordinate system into the substrate stress auxiliary correction matrix S in the principal stress space. Convert the stress tensor matrix under the elastic assumption into the expression of the principal stress space, calculate the substrate yield function value based on the stress tensor matrix in the principal stress space under the elastic assumption, and calculate the substrate yield plasticity multiplier based on the substrate yield function value under the Mohr Coulomb strength criterion and the substrate stress auxiliary correction matrix S in the principal stress space. , according to the substrate yield plasticity multiplier The correction amount is ; Where D represents the rotation matrix from the global coordinate system to the principal stress space; Construct the structural surface strain auxiliary correction matrix, convert the structural surface strain auxiliary correction matrix into column vector form, and calculate the structural surface stress auxiliary correction matrix S in the local coordinate system according to the unit stiffness matrix j ; According to the stress tensor matrix in the local coordinate system after the plastic properties of the substrate are corrected, the structural surface yield function value is calculated, and the structural surface yield plasticity multiplier is calculated based on the structural surface yield function under the Mohr Coulomb strength criterion and the structural surface stress auxiliary correction matrix in the local coordinate system , according to the structural surface yield plasticity multiplier The correction amount is: ; Where C represents the rotation matrix from the global coordinate system to the local coordinate system.

[0013] A further optimization solution is that the calculation method of the actual deformation stress increment matrix includes:

[0014] in, represents the actual stress increment matrix; represents the stress tensor matrix under the elastic assumption.

[0015] This solution also provides a deformation stress increment acquisition system for extremely thin layered weak surrounding rock, which is used to implement the above-mentioned deformation stress increment acquisition method for extremely thin layered weak surrounding rock; the system includes: The acquisition module is used to construct the overall coordinate system and collect the structural surface information of the extremely thin layered weak surrounding rock under the overall coordinate system; A construction module is used to construct a local coordinate system and a rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; Description module, used to describe the stiffness parameters of extremely thin layered weak surrounding rock in the local coordinate system and construct the unit stiffness matrix based on the stiffness parameters; The calculation module is used to obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the unit stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock is deformed in the global coordinate system; The correction calculation module is used to perform plastic characteristic correction on the stress tensor matrix and calculate the actual deformation stress increment matrix.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention provides a method and system for obtaining deformation stress increments of extremely thin layered weak surrounding rock; based on the traditional mechanical property simulation technology of extremely thin layered weak surrounding rock, the method is improved, based on the strain increment matrix of extremely thin layered weak surrounding rock, combined with the rotation matrix and the unit stiffness matrix, under the elastic assumption theory, the stress tensor matrix of the deformation of the extremely thin layered weak surrounding rock in the overall coordinate system is calculated; after correcting the plastic characteristics of the stress increment matrix, the deformation stress increment is calculated, and the stress and deformation characteristics of the extremely thin layered weak surrounding rock are accurately and reasonably described, so that it can be used for the simulation of extremely thin layered weak surrounding rock in continuous medium models such as finite element models and finite difference models, thereby improving the analysis efficiency of extremely thin layered weak surrounding rock projects.

[0017] 2. The present invention provides a method and system for obtaining deformation stress increments of extremely thin layered weak surrounding rock, which takes into account the coupling of substrate yield failure and structural surface yield failure. The entire calculation process conforms to the mathematical principles of plastic mechanics; the calculation of deformation stress increments at each step is more realistic than previous results; in geotechnical engineering fields such as tunnels and slopes, the construction effects such as the surrounding rock plastic zone distribution, surrounding rock deformation distribution, and support structure stress deformation obtained by this method are more accurate, and have higher guiding value for engineering design and construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings: Figure 1 This is a flow chart of the method for obtaining deformation stress increment of extremely thin layered weak surrounding rock; Figure 2 Schematic diagram of the system structure for obtaining deformation stress increment of extremely thin layered weak surrounding rock; Figure 3 This is a schematic diagram comparing the calculation results of this method and the traditional method. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples and drawings. The exemplary embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0020] Traditional methods for simulating the mechanical properties of extremely thin layered surrounding rocks have significant limitations in applications to extremely thin layered weak surrounding rocks, such as ignoring the spacing gradient distribution law unique to thin layered structures, low computational efficiency, and high difficulty. In view of this, this solution provides the following embodiments to solve the above technical problems.

[0021] Example 1 This embodiment provides a method for obtaining deformation stress increment of extremely thin layered weak surrounding rock, such as Figure 1 As shown, the extremely thin layered weak surrounding rock is a weak surrounding rock containing a set of extremely thin layered structural surfaces and meeting the Mohr Coulomb strength criterion. The method includes: Step 1: Construct the overall coordinate system and collect the structural surface information of the extremely thin layered weak surrounding rock under the overall coordinate system; construct the spatial rectangular coordinate system oxyz It is an overall coordinate system, generally with the direction of gravity as the z-axis, the x-axis and the y-axis located in the horizontal plane, forming a 90° angle. oxyz Satisfies the right-hand screw rule.

[0022] The structural surface information includes: the unit normal vector of the structural surface in the global coordinate system ( n x , n y , n z )( n z ≥0), normal spacing l j , normal stiffness k n and shear stiffness k s ; Cohesion of structural surface c j , internal friction angle φ j and dilatancy angle Ψ j ; Young's elastic modulus of rock matrix (without structural surface) E so , Poisson's ratio v , cohesion c , internal friction angle φ and dilatancy angle Ψ .

[0023] Step 2: Construct a local coordinate system and a rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; this step specifically includes the following methods: A local coordinate system that satisfies the right-hand screw rule is constructed with the normal direction of the structural surface as the z' axis of the local coordinate system and the direction of the structural surface as the y' axis of the local coordinate system; wherein the z' axis has direction A as the positive direction, and the direction A is the direction in which the angle between the z' axis and the z axis of the spatial global coordinate system is ≤90°; the x' axis of the local coordinate system has direction B as the positive direction, and the direction B is the direction in which the angle between the x' axis and the z axis of the global coordinate system is ≥90°; According to the unit normal vector of the structural surface in the global coordinate system, the unit direction vector of the local coordinate system in the global coordinate system is calculated; specifically, the unit normal vector of the structural surface in the global coordinate system ( n x , n y , n z ), find the unit direction vectors of the x' axis, y' axis and z' axis in the local coordinate system o'x'y'z' in the global coordinate system oxyz Expressions of when n x = n y =0: x' Unit direction vector of the axis ; y' Unit direction vector of the axis ; z' Unit direction vector of the axis ; when n x ≠0 or n y ≠0: z' Unit direction vector of the axis ; y' Unit direction vector of the axis ; x' Unit direction vector of the axis .

[0024] According to the unit direction vector of the local coordinate system under the global coordinate system, the rotation matrix C from the global coordinate system to the local coordinate system is constructed; ; Step three, describing the stiffness parameters of the extremely thin layered weak surrounding rock in a local coordinate system, and constructing a unit stiffness matrix based on the stiffness parameters; in this step, describing the stiffness parameters of the extremely thin layered weak surrounding rock in a local coordinate system; including the method: The transversely isotropic material method is used to describe the stiffness parameters of extremely thin layered weak surrounding rock. It is assumed that the structural plane only affects the Young's elastic modulus in the direction perpendicular to the structural plane and the shear modulus in the direction parallel to the structural plane. The normal spacing of the structural plane is used to determine the stiffness parameters of the extremely thin layered weak surrounding rock. l j , structural surface shear stiffness k s , structural surface normal stiffness k n , Young's elastic modulus of rock matrix (without structural surface) E so , Poisson's ratio v calculates the stiffness parameter: Young's elastic modulus perpendicular to the structural surface , Young's elastic modulus parallel to the structural surface E' = E so , Poisson's ratio of the x' axis and the y' axis in the structural plane , Poisson's ratio in the x', y' and z' directions within the structural plane v'=v , and the shear modulus parallel to the plane ; ; G so It represents the shear elastic modulus of rock.

[0025] The method of constructing a unit stiffness matrix based on stiffness parameters includes: The first coefficient is calculated according to the following formula M and the second coefficient n : ; ; Based on the first coefficient M and the second coefficient n Construct the element stiffness matrix K: .

[0026] Step 4: Obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the unit stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock is deformed in the global coordinate system; this step specifically includes the following methods: The strain increment matrix in the global coordinate system Represented as a column vector , and according to the elastic assumption theory and the element stiffness matrix, the stress increment matrix under the elastic assumption and the local coordinate system is obtained; the column vector form of the stress increment matrix under the elastic assumption and the local coordinate system is obtained , we get the stress increment matrix under elastic assumption and local coordinate system .

[0027] Specifically, any symmetric matrix A 3×3 The operation rules written in the form of a column vector consisting of 6 components are as follows: , where x corresponds to 1, y corresponds to 2, and z corresponds to 3 in any rectangular coordinate system.

[0028] Based on the rotation matrix C, the stress increment matrix under the elastic assumption and local coordinate system , converted into a stress increment matrix under the elastic assumption and global coordinate system : ; Existing stress tensor matrix in the preset global coordinate system Combining the existing stress tensor matrix and the stress increment matrix under the elastic assumption and the global coordinate system, the stress tensor matrix of the deformation of the extremely thin layered weak surrounding rock in the global coordinate system is obtained. : .

[0029] Step 5: Modify the stress tensor matrix based on its plastic properties and calculate the actual deformation stress increment matrix.

[0030] In this step, the stress tensor matrix is ​​modified in a characteristic manner, including the following method: Assume that the first principal stress, the second principal stress and the third principal stress are 、 、 ; The rock matrix meets the Mohr Coulomb strength criterion, and the stress tensor matrix Transformed into the expression of principal stress space ,according to And the formula Calculate the yield function value of the substrate f s ; Plastic potential function of substrate ,in, , ;in, 、 represent the intermediate parameters related to the internal friction angle and dilatancy angle respectively; represents the internal friction angle of rock; Indicates the shear dilatancy angle of rock; when the yield function value of the substrate f sWhen ≤0, no plastic correction is performed on the stress tensor matrix; when the yield function value of the substrate is f s When >0, the stress tensor matrix is ​​corrected for substrate plasticity; If substrate yield correction is required for the stress increment matrix, the correction amount can be obtained by: Construct the auxiliary matrix of substrate plastic strain: . Convert P into the expression in the local coordinate system ,Will Convert to column vector form ,according to Column vector form of , and then obtain the substrate stress auxiliary correction matrix S1, and convert the stress auxiliary correction matrix S1 into the expression form of the principal stress space , according to the formula and the substrate yield function value f s Calculate the substrate yield plasticity multiplier , according to the substrate yield plasticity multiplier The correction amount is ; Where S represents the expression of the principal stress space of the auxiliary correction matrix of the substrate stress; D represents the rotation matrix from the global coordinate system to the principal stress space, which is composed of the stress tensor matrix It can be uniquely determined that C represents the rotation matrix from the global coordinate system to the local coordinate system; The structural surface yield function under the Mohr-Coulomb strength criterion is: , the structural surface plastic potential function is: ; First determine whether to perform substrate plasticity correction, and calculate the stress tensor matrix in the global coordinate system after the substrate plasticity correction , the calculation method is:

[0031] Will Converted into a stress increment matrix in the local coordinate system after correction of the plastic properties of the substrate , and calculate the structural surface yield function value f sj ; When the structural surface yield function value f sj When ≤0, no plastic correction is performed on the stress tensor matrix; when the yield function value of the structural surface f sj When >0, the stress tensor matrix is ​​plastically corrected.

[0032] If structural surface plastic correction is required for the stress increment matrix, the correction amount can be obtained by: Constructing the auxiliary correction matrix of structural surface strain : , The structural surface strain auxiliary correction matrix Convert to column vector form ,calculate and converted to S j , the yield function is: , combined with the structural surface stress auxiliary correction matrix and the structural surface yield function value f sj Calculate the structural surface yield plasticity multiplier , according to the structural surface yield plasticity multiplier The correction amount is: ; Among them, S j Represents the auxiliary correction matrix of structural surface stress; C represents the rotation matrix from the global coordinate system to the local coordinate system.

[0033] The actual stress increment is calculated based on the stress tensor matrix after characteristic correction; including the method:

[0034] in, represents the actual stress increment matrix; represents the stress increment matrix under the elastic assumption.

[0035] Example 2 This embodiment provides a deformation stress increment acquisition system for extremely thin layered weak surrounding rock, which is used to implement the deformation stress increment acquisition method for extremely thin layered weak surrounding rock described in Example 1; Figure 2 As shown, the system includes: The acquisition module is used to construct the overall coordinate system and collect the structural surface information of the extremely thin layered weak surrounding rock under the overall coordinate system; A construction module is used to construct a local coordinate system and a rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; Description module, used to describe the stiffness parameters of extremely thin layered weak surrounding rock in the local coordinate system and construct the unit stiffness matrix based on the stiffness parameters; The calculation module is used to obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the unit stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock is deformed in the global coordinate system; The correction calculation module is used to perform plastic characteristic correction on the stress tensor matrix and calculate the actual deformation stress increment matrix.

[0036] Example 3 This embodiment provides a computer-readable medium having a computer program stored thereon. The computer program is executed by a processor to implement the method for obtaining deformation stress increments of ultra-thin layered weak surrounding rock as described in Example 1, specifically performing the following steps: Step 1: construct a global coordinate system and collect structural surface information of extremely thin layered weak surrounding rock in the global coordinate system; Step 2: Construct the local coordinate system and the rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; Step 3: describe the stiffness parameters of the extremely thin layered weak surrounding rock in the local coordinate system, and construct the unit stiffness matrix based on the stiffness parameters; Step 4: Obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the element stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock is deformed in the global coordinate system; Step 5: Modify the stress tensor matrix based on its plastic properties and calculate the actual deformation stress increment matrix.

[0037] In this embodiment, the unit normal vector of the known structural surface , the normal spacing of the structural surface is 0.1m, the normal stiffness k n = 1.5×10 11 Pa / m, tangential stiffness k s = 5×10 8 Pa / m. Structural surface cohesion c j =5×10 4 Pa, internal friction angle φ j =18°, dilatancy angle Ψ j =0°; Young's elastic modulus of rock matrix E so =1×10 9 Pa, Poisson's ratio v =0.3, cohesion c =1×10 5 Pa, internal friction angle φ =24° and dilatancy angle Ψ =0°.

[0038] Stress increment in the global coordinate system , current stress state , the deformation stress increment matrix calculated according to the conventional transverse anisotropic pervasive joint model (without considering the substrate yield) is , the deformation stress increment matrix calculated according to this method (considering the yield of the substrate) is The deformation stress increment results obtained by the conventional method and the method of this application are as follows: Figure 3 As shown in the figure, it can be seen that the stress increment calculation results of this method are more accurate than those of conventional methods, which can further make the construction effects such as the surrounding rock plastic zone distribution, surrounding rock deformation distribution, and support structure stress and deformation in engineering analysis more accurate.

[0039] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for obtaining deformation stress increment of extremely thin layered weak surrounding rock, characterized by: The extremely thin layered weak surrounding rock is a weak surrounding rock containing a set of extremely thin layered structural surfaces and meeting the Mohr Coulomb strength criterion. The method includes: Construct a global coordinate system and collect structural surface information of extremely thin layered weak surrounding rock in the global coordinate system; Construct the local coordinate system and the rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; Describe the stiffness parameters of extremely thin layered weak surrounding rock in the local coordinate system, and construct the element stiffness matrix based on the stiffness parameters; Obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the element stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock in the global coordinate system is deformed; The stress tensor matrix is ​​modified according to its plastic properties and the actual deformation stress increment matrix is ​​calculated.

2. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 1, characterized in that: The structural surface information includes: Unit normal vector and normal spacing of the structural surface in the global coordinate system l j , normal stiffness k n and shear stiffness k s ; Cohesion of structural surfaces c j , internal friction angle φ j and dilatancy angle Ψ j ; Young's elastic modulus of rock matrix E so , Poisson's ratio v , cohesion c , internal friction angle φ and dilatancy angle Ψ .

3. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 2, characterized in that: The method of constructing a local coordinate system and a rotation matrix from the global coordinate system to the local coordinate system according to the structural surface information includes: method: A local coordinate system that satisfies the right-hand screw rule is constructed with the normal direction of the structural surface as the z' axis of the local coordinate system and the direction of the structural surface as the y' axis of the local coordinate system; wherein the z' axis has direction A as the positive direction, and the direction A is the direction in which the angle between the z' axis and the z axis of the spatial global coordinate system is ≤90°; the x' axis of the local coordinate system has direction B as the positive direction, and the direction B is the direction in which the angle between the x' axis and the z axis of the global coordinate system is ≥90°; According to the unit normal vector of the structural surface in the global coordinate system, the unit direction vector of the local coordinate system in the global coordinate system is calculated; According to the unit direction vector of the local coordinate system under the global coordinate system, a rotation matrix from the global coordinate system to the local coordinate system is constructed.

4. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 3, characterized in that: The stiffness parameters describing the extremely thin layered weak surrounding rock in the local coordinate system; Included methods: The stiffness parameters of the extremely thin layered weak surrounding rock are described using the transversely isotropic material method. The stiffness parameters include: Young's elastic modulus perpendicular to the structural surface , Young's elastic modulus parallel to the structural surface E' = E so , Poisson's ratio of the x' axis and the y' axis in the structural plane , Poisson's ratio in the x', y' and z' directions within the structural plane v'=v and the shear modulus parallel to the plane ; .

5. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 4, characterized in that: The method of constructing a unit stiffness matrix based on stiffness parameters includes: The first coefficient is calculated according to the following formula M and the second coefficient n : ； ； Based on the first coefficient M and the second coefficient n Construct the element stiffness matrix K: 。 6. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 3, characterized in that: The strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system is obtained, and the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock in the global coordinate system is calculated under the elastic assumption theory in combination with the rotation matrix and the unit stiffness matrix; Includes methods: The strain increment matrix in the global coordinate system is expressed as a column vector, and the stress increment matrix in the elastic assumption and local coordinate system is obtained based on the elastic assumption theory and the element stiffness matrix. Based on the rotation matrix, the stress increment matrix under the elastic assumption and the local coordinate system is converted into the stress increment matrix under the elastic assumption and the global coordinate system; The existing stress tensor matrix in the global coordinate system is preset, and combined with the existing stress tensor matrix and the stress increment matrix under the elastic assumption and the global coordinate system, the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock undergoes deformation in the global coordinate system is obtained.

7. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 6, characterized in that: The method of performing plastic property correction on the stress tensor matrix includes: Convert the stress tensor matrix into the expression of principal stress space to calculate the yield function value of the substrate f s ; When the substrate yield function value f s When ≤0, no plastic correction is performed on the stress tensor matrix; when the yield function value of the substrate is f s When >0, the stress tensor matrix is ​​corrected for substrate plasticity; The yield function value of the structural surface is calculated based on the stress tensor matrix in the local coordinate system after the plastic properties of the substrate are corrected. f sj ; When the structural surface yield function value f sj When ≤0, no plastic correction is performed on the stress tensor matrix; when the yield function value of the structural surface f sj When >0, the stress tensor matrix is ​​plastically corrected.

8. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 7, characterized in that: The method of performing plastic property correction on the stress tensor matrix includes: Construct a substrate strain auxiliary correction matrix in the principal stress space, convert the substrate strain auxiliary correction matrix into the expression form of the local coordinate system and into the column vector form, calculate the substrate stress auxiliary correction matrix in the local coordinate system based on the unit stiffness matrix, and then convert the substrate stress auxiliary correction matrix in the local coordinate system into the substrate stress auxiliary correction matrix S in the principal stress space, convert the stress tensor matrix under the elastic assumption into the expression form of the principal stress space, calculate the substrate yield function value based on the stress tensor matrix in the principal stress space under the elastic assumption, and calculate the substrate yield plasticity multiplier based on the substrate yield function value under the Mohr Coulomb strength criterion and the substrate stress auxiliary correction matrix S in the principal stress space , according to the substrate yield plasticity multiplier The correction amount is ; Where D represents the rotation matrix from the global coordinate system to the principal stress space; Construct the structural surface strain auxiliary correction matrix, convert the structural surface strain auxiliary correction matrix into column vector form, and calculate the structural surface stress auxiliary correction matrix S in the local coordinate system according to the unit stiffness matrix j ; According to the stress tensor matrix in the local coordinate system after the plastic properties of the substrate are corrected, the structural surface yield function value is calculated, and the structural surface yield plasticity multiplier is calculated based on the structural surface yield function under the Mohr Coulomb strength criterion and the structural surface stress auxiliary correction matrix in the local coordinate system , according to the structural surface yield plasticity multiplier The correction amount is: ; Where C represents the rotation matrix from the global coordinate system to the local coordinate system.

9. The method for obtaining deformation stress increment of ultra-thin layered weak surrounding rock according to claim 8, characterized in that: The calculation method of the actual deformation stress increment matrix includes: ； in, represents the actual stress increment matrix; represents the stress tensor matrix under the elastic assumption.

10. A deformation stress increment acquisition system for extremely thin layered weak surrounding rock, characterized by: A method for obtaining deformation stress increments of ultra-thin layered weak surrounding rock according to any one of claims 1 to 9; the system comprises: The acquisition module is used to construct the overall coordinate system and collect the structural surface information of the extremely thin layered weak surrounding rock under the overall coordinate system; A construction module is used to construct a local coordinate system and a rotation matrix from the global coordinate system to the local coordinate system based on the structural surface information; Description module, used to describe the stiffness parameters of extremely thin layered weak surrounding rock in the local coordinate system and construct the unit stiffness matrix based on the stiffness parameters; The calculation module is used to obtain the strain increment matrix of the extremely thin layered weak surrounding rock in the global coordinate system, and combine the rotation matrix and the unit stiffness matrix under the elastic assumption theory to calculate the stress tensor matrix under the elastic assumption when the extremely thin layered weak surrounding rock is deformed in the global coordinate system; The correction calculation module is used to perform plastic characteristic correction on the stress tensor matrix and calculate the actual deformation stress increment matrix.

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