CN116465732A - Method and system for taking value of mechanical parameters of rock mass joint unit - Google Patents
Method and system for taking value of mechanical parameters of rock mass joint unit Download PDFInfo
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Abstract
The invention belongs to the technical field of geotechnical mechanics, and particularly discloses a method and a system for taking the value of mechanical parameters of a rock mass joint unit. The method comprises the following steps: acquiring macroscopic mechanical parameters of the complete rock based on an indoor rock basic mechanical test; carrying out rock mass grading on the engineering rock mass according to the rock mass grading standard to obtain equivalent rock mass mechanical parameters; deducing an elastoplastic stiffness matrix of the joint unit according to Mohr-Coulomb criterion and associated flow rule; and calculating the mechanical parameters of the joint unit according to the homogenization theory and the limit strain theory, and verifying the rationality of the mechanical parameters of the joint unit. The invention is based on the idea of equivalent continuous model, the structural surface is processed into the soft interlayer with a certain thickness, the rock mass is divided into the elastic rock unit and the elastic-plastic joint unit, and the mechanical characteristics of the joint unit are comprehensively obtained through the analysis of the whole joint rock mass unit, so that the engineering calculation precision can be met, and the invention is convenient for directly applying the indoor test data.
Description
Technical Field
The invention belongs to the technical field of geotechnical mechanics, and particularly relates to a method and a system for taking the value of mechanical parameters of a rock mass joint unit.
Background
The rock mass acts as a body that experiences a lengthy diagenetic history, with a large number of fractures and joints generally distributed within the body. The number of the micro cracks is large, the size is small, the cutting degree of the rock mass is high, and the mechanical property and deformation characteristic of the rock mass are directly affected. However, since the number of joint cracks is extremely large, simulation is not feasible one by one, and therefore, how to simulate a rock mass structure with numerous joint cracks accurately and efficiently becomes a problem to be solved urgently in the rock mass engineering industry.
At present, two main ideas exist for solving strategies of equivalent rock mass structures. The first idea is based on the recognition that defects in geotechnical materials are prevalent, and is based on the rock mass characterization unit method (Zhou Chuangbing, three major. Theory of rock mass characterization unit volume REV-a basic problem of rock mass mechanical parameter value [ J ]. Engineering geology report, 1999,7 (4): 332-336.) established by analyzing the influence of discontinuous structures on the overall mechanical behavior of the material. The method comprises the steps of dividing rock mass grades according to national standard BQ, GSI, RQD indexes and other rock mass grading standards, obtaining rock mass mechanical parameters, combining numerical simulation analysis to determine rock mass characterization unit volume (REV), taking the mechanical parameters of the rock mass characterization unit as the mechanical parameters of engineering scale rock mass (Kulatilike PHS W.Estimating elastic constants and strength of discontinuous rock [ J ] Journal of geotechnical engineering,1985,111 (7): 847-864. How full, xue Tinghe, peng Yanfei. Research on engineering rock mass mechanical parameter determination methods [ J ]. Rock mechanics and engineering theory, 2001 (02): 225-229.). In addition, chinese patent CN113946958A discloses a method for solving a rock mass characterization unit REV based on a discrete fracture network method, and the method can reasonably reflect the macroscopic mechanical behavior of a general fractured rock mass, is a popular method in the current engineering world, but is influenced by size effect, and the laboratory test data of the rock mass cannot be used as a main basis for parameter selection. The second concept is to consider a rock mass as a two-phase formation of a complete rock and a structural plane, wherein both rock units and structural plane units are considered as isotropic bodies, but the rock mass units combined by the two are anisotropic bodies. The method unifies two damage forms of damage along joint surfaces and rock damage through an intensity equivalent principle to obtain mechanical parameters of the whole rock mass. The method for equivalent strength is the front edge of the current academic research, wherein rock mechanical parameters are obtained through an indoor mechanical test, and the value of the mechanical parameters of the joint unit becomes the key of whether the model can accurately represent the mechanical characteristics and the damage characteristics of the rock mass structure.
In summary, the current solving method related to the equivalent rock mass structure still has a certain defect, and the main appearance is that: (1) The node distribution in the natural rock mass is wide, and the analyzed medium has discrete uncertainty, and if the medium is treated as a node unit, great difficulty is brought to numerical modeling and calculation; (2) The REV value of the rock mass is usually very large or even absent, and the test result of the laboratory sample cannot be directly used as the mechanical parameter value basis of the rock mass characterization unit.
Based on the above-mentioned defects and shortcomings, a new method for evaluating mechanical parameters of a rock mass joint unit is needed in the art to overcome the uncertainty of discrete analysis of the medium and the inaccuracy of evaluating according to the test result in the prior art.
Disclosure of Invention
Aiming at the defects or improvement demands of the prior art, the invention provides a method and a system for taking the value of the mechanical parameters of a rock mass joint unit, which are based on the idea of an equivalent continuous model, process a structural surface into a weak interlayer with a certain thickness, divide the rock mass into an elastic rock unit and an elastoplastic joint unit, and comprehensively obtain the mechanical characteristics of the joint unit through analyzing the whole joint rock unit. The method integrates the indoor mechanical test and rock quality classification, not only can meet engineering calculation precision, but also is convenient for directly applying the indoor test data.
In order to achieve the above object, according to one aspect of the present invention, a method for evaluating mechanical parameters of a rock mass joint unit is provided, comprising the steps of:
s1, acquiring macroscopic mechanical parameters of the complete rock based on an indoor rock basic mechanical test;
s2, classifying the rock mass of the engineering rock mass according to the rock mass quality classification standard to obtain equivalent rock mass mechanical parameters;
s3, deducing an elastic-plastic rigidity matrix of the joint unit according to Mohr-Coulomb criterion and associated flow rule;
s4, substituting the mechanical parameters of the complete rock, the mechanical parameters of the equivalent rock and the elastic-plastic rigidity matrix of the joint unit to calculate the strength parameters of the joint unit according to the homogenization theory, and simultaneously, calculating the limit strain of the equivalent rock based on the limit strain theory and the mechanical parameters of the equivalent rock;
s5, calculating the fracture energy of the mechanical unit according to the ultimate strain of the equivalent rock mass and the strength parameter of the joint unit, and determining the mechanical parameter of the joint unit according to the fracture energy.
As a further preference, in step S1, the room rock is substantially mechanicallyThe test comprises rock uniaxial compression and rock Brazilian fracture test, and the elastic modulus E of the complete rock is obtained according to the rock uniaxial compression test r And Poisson ratio v r The method comprises the steps of carrying out a first treatment on the surface of the Obtaining the tensile strength f of the complete rock according to the Brazilian rock splitting test t r 。
As a further preferred aspect, in step S2, the equivalent rock mass mechanical parameter comprises an elastic modulus E m Poisson ratio v m Cohesive force c m Angle of internal frictionAnd tensile strength f t m 。
As a further preference, step S3 comprises the steps of:
s31 building a yield function f and a first material parameter m (kappa) and a second material parameter sigma c (kappa) expression, selecting Mohr-Coulomb criterion as yield criterion of the joint unit, constructing yield function:
f(σ 1 ,σ 3 ,κ)＝m(κ)σ 1 -σ 3 -σ c (κ)＝0
in sigma 1 Sum sigma 3 The maximum principal stress and the minimum principal stress of the material are respectively, and the internal variable kappa represents the hardening degree of the material;
s32, constructing an elastoplastic stiffness matrix of the joint unit, wherein the elastoplastic stiffness matrix [ K ] of the joint unit is constructed by adopting a flow rule associated with a yielding surface through plastic deformation ep ]The calculation model of (2) is as follows:
in [ K ] e ]The elastic stiffness matrix of the joint unit is represented by R, R and sigma, wherein R is the hardening modulus, and sigma is the vector representation of the stress of the joint unit.
As a further preference, step S4 comprises the steps of:
s41, solving joint unit rigidity: solving the normal direction of the joint unit according to the rigidity equivalent principle of the continuous mediumRigidity K N And tangential stiffness K S ；
S42, solving the tensile strength and the shear strength of the joint unit: according to the homogenization theory requirement, the yield points of the joint unit and the equivalent rock mass unit are kept consistent, and the tensile strength f of the joint unit is constructed t Initial cohesion c 0 And initial internal friction forceIs a calculation formula of (2).
As a further preferred feature, the normal stiffness K of the joint unit N And tangential stiffness K S The calculation formula of (2) is as follows:
in the method, in the process of the invention,h is the thickness of the equivalent rock mass unit, E r And v r Elastic modulus and poisson ratio of the complete rock, E m And v m The elastic modulus and the poisson ratio of the engineering rock mass are respectively;
as a further preference, the tensile strength f of the joint unit t Initial cohesion c 0 And initial internal friction forceThe calculation formulas of (a) are respectively as follows:
f t ＝f t m
in the method, in the process of the invention,f t m 、c m and->Tensile strength, cohesion and internal friction angle of equivalent rock mass units, respectively +.>Is the shear strain of the equivalent rock mass at the initial yield point.
As a further preferred aspect, in step S4, the calculating the equivalent rock mass limit strain includes: according to the limit strain theory, solving by adopting a numerical limit analysis methodAnd->
In the method, in the process of the invention,c is the lateral strain of the equivalent rock mass unit under the unidirectional compression condition m Is the cohesion of the equivalent rock mass unit, < +.>Is the internal friction angle of the equivalent rock mass unit E m And v m The elastic modulus and poisson ratio of the equivalent rock mass are respectively.
As a further preference, in step S5, the type I breaking energy G of the joint is calculated from the stress-strain curve of the joint I And type II break energy G II ：
Wherein f s And f s ' initial shear strength and residual shear strength of the joint unit, respectively; delta epsilon and delta gamma are the normal and tangential cumulative strains of the joint unit from the initial yield point to the failure point, respectively.
As a further preferred aspect, the method further comprises: based on finite-discrete element coupling software/program, carrying out numerical simulation on uniaxial compression and Brazilian split test, and verifying the applicability and rationality of the mechanical parameter value of the joint unit.
According to another aspect of the invention, a system for evaluating mechanical parameters of a rock mass joint unit is also provided, for implementing the method.
In general, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:
1. the invention is based on the idea of equivalent continuous model, the structural surface in the engineering rock mass is processed into a weak interlayer with a certain thickness, and the equivalent rock mass unit is divided into an elastic rock unit and an elastic-plastic joint unit, so that the anisotropic equivalent rock mass unit can be divided into two interactive isotropic units. The established equivalent rock mass model not only considers the influence of the joint on the mechanical property of the rock mass, but also can be regarded as a continuous body in a macroscopic sense, thereby overcoming the problems of difficult modeling and low calculation efficiency when the conventional method simulates the general joint fracture rock mass.
2. According to the invention, the influence of the joint on the mechanical property of the rock mass is considered, the Mohr-Coulomb criterion and the related flow rule are adopted to describe the elastoplastic deformation of the joint unit, and the calculation formula of the mechanical parameter of the joint unit is deduced by comprehensively analyzing the whole joint rock mass unit based on the homogenization theory and the limit strain theory. The derivation process comprehensively considers the indoor mechanical test and rock mass quality classification, thereby overcoming the inaccuracy of the traditional method which directly adopts the indoor mechanical test result and reflecting the macroscopic mechanical behavior of the jointed rock mass more accurately.
3. The physical meaning of the calculated parameters in the mechanical parameter value formula of the joint unit deduced by the invention is clear, the calculated parameters can be obtained through rock mechanical test results and rock mass quality grading standards, the value result can be verified through finite-discrete element coupling software/program, and the method is simple, convenient, high in practicability and easy to popularize, and is an equivalent parameter analysis method of the joint rock mass, which can not only meet engineering calculation precision, but also is convenient for directly applying indoor test data.
Drawings
FIG. 1 is a flow chart of a method for evaluating mechanical parameters of a rock mass joint unit according to an embodiment of the present invention;
fig. 2 (a) is a schematic diagram of an indoor uniaxial compression test, and fig. 2 (b) is a schematic diagram of an indoor brazilian split test;
fig. 3 (a) is a graph showing the trend of the adhesion parameter of the joint unit according to the method of the present invention with κ, and fig. 3 (b) is a graph showing the trend of the friction angle parameter of the joint unit according to the method of the present invention with κ;
fig. 4 (a) is a normal stress-strain curve of the joint unit, and fig. 4 (b) is a tangential stress-strain curve of the joint unit;
fig. 5 (a) is a diagram of an FDEM-uniaxial compression numerical simulation model according to the present invention, and fig. 5 (b) is a diagram of an FDEM-brazilian split numerical simulation model according to the present invention;
fig. 6 (a) is a simulated finite-discrete element stress-strain curve of uniaxial compression values according to the present invention, and fig. 6 (b) is a simulated finite element stress-strain curve of brazilian split values according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
As shown in fig. 1, the method for evaluating mechanical parameters of a rock mass joint unit provided by the embodiment of the invention comprises the following steps:
and step 1, acquiring macroscopic mechanical parameters of the complete rock based on an indoor rock basic mechanical test. Based on the basic mechanical test of the indoor rock, macroscopic mechanical parameters of the complete rock are obtained. Specifically, in the step 1, the rock mechanics test includes uniaxial compression and brazilian split test, as shown in fig. 2. Obtaining the elastic modulus E of the complete rock according to the rock uniaxial compression test r And Poisson ratio v r The method comprises the steps of carrying out a first treatment on the surface of the Obtaining the tensile strength f of the complete rock according to the Brazilian rock splitting test t r . In the invention, the uniaxial compression and Brazilian split test belong to the prior art, and the conventional uniaxial compression and Brazilian split test can meet the requirement of acquiring the rock parameters of the invention. The specific structure and method are not described in detail in this invention.
And 2, classifying rock mass grades based on rock mass quality classification standards, and obtaining macroscopic mechanical parameters of the engineering rock mass. Namely: and carrying out rock mass grading on the engineering rock mass according to the rock mass grading standard to obtain equivalent rock mass mechanical parameters. Specifically, the rock mass quality grade classification standard comprises national standard BQ, GSI, RQD indexes and the like. Classifying the rock mass in the engineering according to the rock mass quality classification standard to obtain the elastic modulus E of the engineering rock mass m Poisson ratio v m Adhesive and cohesiveForce c m Angle of internal frictionAnd tensile strength f t m 。
And 3, deriving an elastoplastic stiffness matrix of the joint unit based on Mohr-Coulomb criteria and associated flow rules. Specifically, the elastoplastic stiffness matrix of the joint unit may be solved as follows:
step 3.1, constructing the yield function f and the first material parameter m (κ) and the second material parameter σ c (kappa) expression: the Mohr-Coulomb criterion is selected as the yield criterion of the joint unit, then the yield function f (sigma 1 ,σ 3 Kappa) can be expressed as:
f(σ 1 ,σ 3 ,κ)＝m(κ)σ 1 -σ 3 -σ c (κ)＝0 (1)
wherein sigma 1 Sum sigma 3 The maximum principal stress and the minimum principal stress of the material, respectively; the internal variable κ characterizes the degree of hardening of the material, which determines how the yield surface of the hardened/softened material will change, the value of which is usually related to plastic strain; the first material parameter m (κ) is the ratio of the characterizing compressive strength to the characterizing tensile strength; second material parameter sigma c (kappa) characterizes unconfined compressive strength. First material parameter m (κ) and second material parameter σ c The expression of (κ) and the internal variable κ is:
wherein c (kappa) andthe cohesion and internal friction angle of the jointed rock mass, respectively, are linear functions of the internal variable k in the elastoplastic phase, i.e., decrease with increasing internal variable k, but to different extents, as shown in fig. 3. c 0 And->The initial cohesion and initial internal friction angle of the joint unit, respectively +.>And kappa (kappa) r The internal friction angle and the internal variable when the unit is completely destroyed;and dε p Equivalent plastic strain and plastic strain delta, respectively.
Step 3.2, constructing a rigidity matrix K of the joint unit: the plastic deformation uses the flow law associated with the yielding surface, then the elastoplastic stiffness matrix of the joint element [ K ep ]The expression of (2) is:
wherein [ K ] e ]Is the elastic rigidity matrix of the joint unit, K N And K S Is the normal rigidity and tangential rigidity coefficient of the joint unit; r is the hardening modulus, and at the yield point, R is 0; σ is a vector representation of the joint cell stress.
And 4, calculating mechanical parameters of the joint unit based on a homogenization theory and a limit strain theory. In the invention, the homogenization theory is to combine units with two different mechanical properties into a new unit by using a homogenization criterion and stress balance and motion constraint conditions. According to the homogenization theory, the relative displacement between the joint and the rock occurs inside the joint unit, and the two interfaces remain completely bonded. The homogenization theory requires that the yield points of the joint unit and the equivalent rock mass unit remain consistent, i.e. when the joint unit reaches the yield strain, the stress states of the joint unit and the rock mass unit all meet the yield function at the moment. The limit strain theory is to take limit strain under unidirectional stress as a criterion of damage of rock-soil materials under unidirectional stress. The ultimate strain theory considers that when a material just reaches yield, the material is initially yield, has elastic ultimate strain, and as plasticity progresses, the material breaks down, and the strain reaches the ultimate strain. The equivalent rock mass unit and the joint unit adopt an elastoplastic mechanism, so that it is feasible to calculate the limit strain of the rock mass unit and the joint unit by utilizing the limit strain theory.
In the step 4, the rock unit adopts an elastic structure, the rock body unit adopts an ideal elastic-plastic structure, and the mechanical parameters of the joint unit can be calculated according to the following steps:
step 4.1, solving the joint unit rigidity: according to the rigidity equivalent principle of the continuous medium, the normal rigidity K of the joint unit N And tangential stiffness K S The calculation formula is as follows:
wherein:
wherein h is the thickness of the equivalent rock mass unit; e (E) r And v r The elastic modulus and the poisson ratio of the complete rock are respectively obtained, and the initial straight line segment of the stress-strain curve is valued according to the indoor uniaxial compression test; e (E) m And v m The elastic modulus and the poisson ratio of the equivalent rock mass are respectively calculated according to the rock mass quality grading standard.
Step 4.2, solving the tensile strength and the shear strength of the joint unit: according to the homogenization theory requirement, the yield points of the joint unit and the equivalent rock mass unit are kept consistent, and the tensile strength f of the joint unit t Initial cohesion c 0 And initial internal friction forceThe calculation formula of (2) is as follows:
f t ＝f t m (16)
wherein:
wherein f t m 、c m Andrespectively the tensile strength, cohesive force and internal friction angle of the equivalent rock mass unit, and taking values according to the rock mass quality grading standard; />The specific value of the shear strain of the equivalent rock mass at the initial yield point is shown in step 4.3.
Step 4.3, solving the fracture energy of the joint unit: FIG. 4 is a stress-strain curve of an element of a joint, the area enclosed by the curve at the post-yielding stage being the breaking energy of the element, the type I breaking energy G of the element of the joint I And type II break energy G II The calculation formula of (2) is as follows:
wherein f s And f s ' initial shear strength and residual shear strength of the joint unit, respectively; delta epsilon and delta gamma are the normal and tangential cumulative strains of the joint unit from the initial yield point to the failure point, respectively. The formulas for Δε and Δγ are as follows:
wherein t is the thickness of the joint unit;and->The initial yield point and the tensile strain at the complete failure point are the tensile failure of the equivalent rock mass unit; />And->Is the shear strain at the initial yield point and the point of complete failure at the time of shear failure of the equivalent rock mass unit. According to the theory of extreme strain->And->The numerical limit analysis method can be used for solving, and the relation formula of the numerical limit analysis method is as follows:
wherein,,is the lateral strain of the equivalent rock mass unit under unidirectional compression.
And 5, carrying out numerical simulation on the uniaxial compression and Brazilian split test based on finite-discrete element coupling software, and verifying the applicability and rationality of the mechanical parameter value method of the joint unit. In the step 5, the mechanical parameters of the whole rock in the step 1 are used as input parameters of a physical unit, and the mechanical parameters of the joints calculated in the steps 3 to 4 are used as input parameters of the joint unit to perform numerical simulation of uniaxial compression and Brazilian split through finite-discrete element software. The numerical model is shown in fig. 5 (a) (b), and the model stress-strain curve results are shown in fig. 6 (a) and (b). The applicability and rationality of the mechanical parameter value method of the rock mass joint unit provided by the invention are verified by comparing the finite-discrete element simulation result with the engineering rock mass quality grading result.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The method for evaluating the mechanical parameters of the rock mass joint unit is characterized by comprising the following steps of:
s1, acquiring macroscopic mechanical parameters of the complete rock based on an indoor rock basic mechanical test;
s2, classifying the rock mass of the engineering rock mass according to the rock mass quality classification standard to obtain equivalent rock mass mechanical parameters;
s3, deducing an elastic-plastic rigidity matrix of the joint unit according to Mohr-Coulomb criterion and associated flow rule;
s4, substituting the mechanical parameters of the complete rock, the mechanical parameters of the equivalent rock and the elastic-plastic rigidity matrix of the joint unit to calculate the strength parameters of the joint unit according to the homogenization theory, and simultaneously, calculating the limit strain of the equivalent rock based on the limit strain theory and the mechanical parameters of the equivalent rock;
s5, calculating the fracture energy of the joint unit according to the ultimate strain of the equivalent rock mass and the strength parameter of the joint unit, and determining the mechanical parameter of the joint unit according to the fracture energy.
2. The method for evaluating mechanical parameters of a rock mass joint unit according to claim 1, wherein in step S1, the indoor rock basic mechanical test comprises a rock uniaxial compression test and a rock brazil split test, and the elastic modulus Er and poisson ratio v of the whole rock are obtained according to the rock uniaxial compression test r The method comprises the steps of carrying out a first treatment on the surface of the Obtaining the tensile strength f of the complete rock according to the Brazilian rock splitting test t r 。
3. The method for evaluating mechanical parameters of a rock mass joint unit according to claim 1, wherein in step S2, the equivalent rock mass mechanical parameters include an elastic modulus E m Poisson ratio v m Cohesive force c m Angle of internal frictionAnd tensile strength f t m 。
4. The method for evaluating mechanical parameters of a rock mass joint unit according to claim 1, wherein the step S3 comprises the steps of:
s31 building a yield function f and a first material parameter m (kappa) and a second material parameter sigma c (kappa) expression, selecting Mohr-Coulomb criterion as yield criterion of the joint unit, constructing yield function:
f(σ 1 ,σ 3 ,κ)＝m(κ)σ 1 -σ 3 -σ c (κ)＝0
in sigma 1 Sum sigma 3 The maximum principal stress and the minimum principal stress of the material are respectively, and the internal variable kappa represents the hardening degree of the material;
s32, constructing an elastoplastic stiffness matrix of the joint unit, wherein the elastoplastic stiffness matrix [ K ] of the joint unit is constructed by adopting a flow rule associated with a yielding surface through plastic deformation ep ]The calculation model of (2) is as follows:
in [ K ] e ]The elastic stiffness matrix of the joint unit is represented by R, R and sigma, wherein R is the hardening modulus, and sigma is the vector representation of the stress of the joint unit.
5. The method for evaluating mechanical parameters of a rock mass joint unit according to claim 1, wherein step S4 comprises the steps of:
s41, solving joint unit rigidity: solving the normal rigidity K of the joint unit according to the rigidity equivalent principle of the continuous medium N And tangential stiffness K S ；
S42, solving the tensile strength and the shear strength of the joint unit: according to the homogenization theory requirement, the yield points of the joint unit and the equivalent rock mass unit are kept consistent, and the tensile strength f of the joint unit is constructed t Initial cohesion c 0 And initial internal friction forceIs a calculation formula of (2).
6. The method for evaluating mechanical parameters of a rock mass joint unit according to claim 5, wherein the normal stiffness K of the joint unit N And tangential stiffness K S The calculation formula of (2) is as follows:
in the method, in the process of the invention,h is the thickness of the equivalent rock mass unit, E r And v r Elastic modulus and poisson ratio of the complete rock, E m And v m The elastic modulus and the poisson ratio of the equivalent rock mass are respectively;
tensile strength f of the joint unit t Initial cohesion c 0 And initial internal friction forceThe calculation formulas of (a) are respectively as follows:
f t ＝f t m
in the method, in the process of the invention,f t m 、c m and->Tensile strength, cohesion and internal friction angle of equivalent rock mass units, respectively +.>Is the shear strain of the equivalent rock mass at the initial yield point.
7. The method according to claim 1, wherein the mechanical parameter of the rock mass joint unit is a valueThe method is characterized in that in step S4, the calculating the equivalent rock mass limit strain comprises: according to the limit strain theory, solving by adopting a numerical limit analysis methodAnd->
In the method, in the process of the invention,c is the lateral strain of the equivalent rock mass unit under the unidirectional compression condition m As the cohesion of the equivalent rock mass unit,is the internal friction angle of the equivalent rock mass unit E m And v m The elastic modulus and poisson ratio of the equivalent rock mass are respectively.
8. The method for evaluating mechanical parameters of a rock mass joint unit according to claim 1, wherein in step S5, the type I breaking energy G of the joint unit is calculated from the stress-strain curve of the joint unit I And type II break energy G II ：
Wherein f s And f' s The initial shear strength and the residual shear strength of the joint unit are respectively; delta epsilon and delta gamma are the normal and tangential cumulative strains of the joint unit from the initial yield point to the failure point, respectively.
9. The method for evaluating mechanical parameters of a rock mass joint unit according to any one of claims 1 to 8, further comprising: based on finite-discrete element coupling software, carrying out numerical simulation on uniaxial compression and Brazilian split tests, and verifying the applicability and rationality of the mechanical parameter values of the joint units.
10. A system for the valuing of mechanical parameters of a rock mass joint unit, characterized by implementing the method of any one of claims 1-9.
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| CN117409870A (en) * | 2023-10-18 | 2024-01-16 | 中国矿业大学 | Mesomechanics prediction method for lateral limit compression deformation of soil-rock mixture |
| CN117409870B (en) * | 2023-10-18 | 2024-05-24 | 中国矿业大学 | Mesomechanics prediction method for lateral limit compression deformation of soil-rock mixture |
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