An evaluation method and system considering stress deflection induced rock mass crack activation and propagation

Abstract

The application discloses an evaluation method and system considering stress deflection induced rock mass crack activation and expansion, and the method comprises the following steps: obtaining basic mechanical parameters of a rock mass to be evaluated and a stress environment thereof; performing initial stress state analysis on the rock mass to be evaluated, constructing an initial state mechanical model of a structural surface, and solving initial state stress parameters; analyzing the influence of an excavation disturbance source, performing disturbance stress state analysis, constructing a mechanical analysis model under the influence of disturbance stress, and solving disturbance state stress parameters; performing geometric analysis of stress Mohr circles and strength curves in different states based on the initial stress state and the disturbance stress state; deriving a conditional equation of rock mass structural surface crack activation and expansion based on the disturbance stress state and the basic mechanical parameters, and performing rock mass crack activation damage risk evaluation and crack type discrimination based on the conditional equation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rock mass crack damage risk assessment, and particularly relates to an evaluation method and system considering stress deflection induced rock mass crack activation and expansion. BACKGROUND

[0002] The activation of internal cracks of surrounding rock in underground engineering has a direct impact on the failure mode and characteristics of rock mass. From the perspective of the internal structural integrity of rock strata, the instability of surrounding rock is often caused by the weakening or disappearance of rock mass bearing capacity due to the activation and expansion of internal cracks of rock mass, resulting in rock deformation or separation. In engineering, the stability of surrounding rock is often judged by the degree of internal damage and deterioration of rock mass, which helps to take targeted treatment measures.

[0003] At present, the existing rock mass damage discrimination and solving method lacks consideration of the stress size and direction environment of surrounding rock. Therefore, the application solves the problems in the above background by considering the stress environment to solve the rock mass crack activation and expansion method. SUMMARY

[0004] The application aims to solve the problems of the prior art and provides the following solutions.

[0005] An evaluation method considering stress deflection induced rock mass crack activation and expansion, comprising the following steps:

[0006] Obtaining the basic mechanical parameters of the rock mass to be evaluated and the stress environment thereof;

[0007] Performing initial stress state analysis on the rock mass to be evaluated, constructing an initial state mechanical model of the structural surface, and solving the initial state stress parameters;

[0008] Performing disturbance stress state analysis by analyzing the influence of excavation disturbance source, constructing a mechanical analysis model under the influence of disturbance stress, and solving the disturbance state stress parameters;

[0009] Performing geometric analysis of the stress Mohr circle and the strength curve under different states based on the initial stress state and the disturbance stress state;

[0010] Based on the disturbance stress state, the condition equation of rock mass structural surface crack activation and expansion is derived based on the basic mechanical parameters, and the rock mass crack activation damage risk is evaluated and the crack type is distinguished based on the condition equation.

[0011] Preferably, the basic mechanical parameters include elastic modulus, Poisson's ratio, cohesion, internal friction angle and tensile strength.

[0012] The stress environment includes stress size, stress direction and external force disturbance source.

[0013] Preferably, the method for solving the initial state stress parameter comprises:

[0014]

[0015] wherein σ represents the initial state structural plane normal stress parameter, σ1 represents the initial state maximum principal stress, σ3 represents the initial state minimum principal stress, θ represents the angle between the structural plane and the horizontal direction, and τ represents the initial state structural plane tangential stress parameter.

[0016] Preferably, the method for solving the perturbed state stress parameter comprises:

[0017]

[0018] l=sinθ, m=cosθ

[0019] σ' x =σ'3cosθ, σ' y =σ'1cosθ

[0020] τ' xy =σ'3sinθ, τ' yx =-σ'1sinθ

[0021] wherein p x represents the horizontal stress component, p y represents the vertical stress component, l represents the horizontal cosine, m represents the vertical cosine, σ' x represents the perturbed state x-direction stress, σ' y represents the perturbed state y-direction stress, τ' xy represents the perturbed state xy-direction shear stress, τ' yx represents the perturbed state yx-direction shear stress, σ'1 represents the perturbed state maximum principal stress, and σ'3 represents the perturbed state minimum principal stress.

[0022] Preferably, the conditional equation comprises:

[0023]

[0024] wherein c w represents the cohesion of the structural plane, represents the internal friction angle of the structural plane, and α represents the perturbed state stress deflection direction.

[0025] The application further provides an evaluation system considering stress deflection induced rock mass crack activation and expansion, which applies the above method and comprises a parameter acquisition module, an initial state calculation module, a perturbed state calculation module, a geometric analysis module and an evaluation module.

[0026] The parameter acquisition module is configured to acquire basic mechanical parameters of the rock mass to be evaluated and a stress environment in which the rock mass to be evaluated is located.

[0027] The initial state calculation module is configured to perform initial stress state analysis on the rock mass to be evaluated, construct an initial state mechanical model of a structural plane, and solve initial state stress parameters.

[0028] The disturbed state calculation module is configured to analyze an influence of an excavation disturbance source, perform disturbed stress state analysis, construct a mechanical analysis model under the influence of disturbed stress, and solve disturbed state stress parameters.

[0029] The geometric analysis module is configured to perform geometric analysis of stress Mohr circles and strength curves in different states based on the initial stress state and the disturbed stress state.

[0030] The evaluation module is configured to derive a condition equation of crack activation and expansion of a rock mass structural plane based on the disturbed stress state and the basic mechanical parameters, and perform rock mass crack activation damage risk evaluation and crack type discrimination based on the condition equation.

[0031] Preferably, the basic mechanical parameters include an elastic modulus, a Poisson's ratio, a cohesion, an internal friction angle, and a tensile strength.

[0032] The stress environment includes a stress size, a stress direction, and an external force disturbance source.

[0033] Preferably, in the initial state calculation module, a method for solving the initial state stress parameters includes:

[0034]

[0035] wherein σ represents an initial state structural plane normal stress parameter, σ1 represents an initial state maximum principal stress, σ3 represents an initial state minimum principal stress, θ represents an angle between the structural plane and the horizontal direction, and τ represents an initial state structural plane tangential stress parameter.

[0036] Preferably, in the disturbed state calculation module, a method for solving the disturbed state stress parameters includes:

[0037]

[0038] l=sinθ, m=cosθ

[0039] σ′ x =σ′3cosθ,σ′ y =σ′1cosθ

[0040] τ′ xy =σ′3sinθ,τ′ yx =-σ′1sinθ

[0041] wherein, p x represents a horizontal stress component, p y represents a vertical stress component, l represents a horizontal cosine, m represents a vertical cosine, σ′ x represents a disturbed state x-direction stress, σ′ y represents a disturbed state y-direction stress, τ′ xy represents a disturbed state xy-direction shear stress, τ′ yx represents a disturbed state yx-direction shear stress, σ′1 represents a disturbed state maximum principal stress, and σ′3 represents a disturbed state minimum principal stress.

[0042] Preferably, in the evaluation module, the conditional equation comprises:

[0043]

[0044] wherein, c w represents a cohesion of a structural surface, represents an internal friction angle of the structural surface, and α represents a stress deflection direction of a disturbed state.

[0045] Compared with the prior art, the present application has the following beneficial effects:

[0046] The present application calculates and discriminates the rock mass crack activation and damage by considering the real stress environment of the rock mass, comprehensively considering the size and direction of the stress, and achieves the purpose of accurately and properly protecting and managing the disaster caused by the rock mass instability risk, thereby solving the problem of the insufficient rock mass instability risk discrimination under the influence of the underground engineering excavation, and further providing a reference for the reasonable support of the rock mass stability. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the present application, the following briefly introduces the drawings needed to be used in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0048] Figure 1 The figure is a method flowchart of the embodiment of the present application.

[0049] Figure 2 The figure is a structural surface initial state mechanical model schematic diagram of the embodiment of the present application.

[0050] Figure 3 The figure is a mechanical analysis model schematic diagram under the influence of the disturbed stress of the embodiment of the present application, wherein, a is a non-principal stress plane state under the disturbed state, b represents a principal stress plane state after stress transformation, and c represents a principal stress plane state after coordinate system transformation.

[0051] Figure 4 Fig. 8 is a schematic diagram of stress Mohr circle and strength curve in different states of an embodiment of the present application, wherein a represents an initial state, and b represents a perturbed state;

[0052] Figure 5 Fig. 9 is a schematic diagram of a theoretical model of crack formation of a moving rock mass of an embodiment of the present application. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0054] In order to make the above objectives, characteristics and advantages of the present application more apparent, comprehensible and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0055] Embodiment One

[0056] In this embodiment, as shown in Fig. 1, an evaluation method considering stress deflection induced rock mass crack activation and expansion includes the following steps: Figure 1

[0057] S1. Obtain basic mechanical parameters of the rock mass to be evaluated and the stress environment thereof.

[0058] The basic mechanical parameters include elastic modulus, Poisson's ratio, cohesion, internal friction angle and tensile strength; and the stress environment includes stress size, stress direction and external force perturbation source.

[0059] In this embodiment, first, the underground engineering rock mass is sampled, and at the same time, in-situ stress testing is performed. Then, the obtained rock sample is sealed and stored, and the basic mechanical parameters of the rock mass are tested through laboratory testing.

[0060] S2. For the rock mass to be evaluated, initial stress state analysis is performed, an initial state mechanical model of the structural plane is constructed, and initial state stress parameters are solved.

[0061] In this embodiment, the constructed initial state mechanical model of the structural plane is as shown in Fig. 2, AB is a rock mass structural plane, and the method for solving the initial state stress parameters includes: Figure 2

[0062]

[0063] ​​wherein, σ represents the initial state structural plane normal stress parameter, σ1 represents the initial state maximum principal stress, σ3 represents the initial state minimum principal stress, θ represents the angle between the structural plane and the horizontal direction, and τ represents the initial state structural plane tangential stress parameter.

[0064] S3. Analyze the influence of excavation disturbance source, perform disturbance stress state analysis, construct a mechanical analysis model under the influence of disturbance stress, and solve the disturbance state stress parameter.

[0065] In this embodiment, the mechanical analysis model under the influence of disturbance stress constructed is as shown in Figure 3 AB is the rock mass structural plane, α is the disturbance state stress deflection direction, and the method for solving the disturbance state stress parameter comprises:

[0066]

[0067] l=sinθ, m=cosθ

[0068] σ′ x =σ′3cosθ, σ′ y =σ′1cosθ

[0069] τ′ xy =σ′3sinθ, τ′ yx =-σ′1sinθ

[0070] wherein, p x represents the horizontal direction stress component, p y represents the vertical direction stress component, l represents the horizontal direction cosine, m represents the vertical direction cosine, σ′ x represents the disturbance state x direction stress, σ′ y represents the disturbance state y direction stress, τ′ xy represents the disturbance state xy direction shear stress, τ′ yx represents the disturbance state yx direction shear stress, σ′1 represents the disturbance state maximum principal stress, and σ′3 represents the disturbance state minimum principal stress.

[0071] S4. Based on the initial stress state and the disturbance stress state, perform stress Mohr circle and strength curve geometric analysis under different states.

[0072] Perform stress Mohr circle and strength curve geometric analysis on the initial stress state and the excavation disturbance stress state, analyze the three geometric relationships of the strength curve and the stress Mohr circle, namely, apart, tangent, and intersect, wherein, the apart corresponds to the stable state, the tangent corresponds to the limit equilibrium state, and the intersect corresponds to the crack propagation state. Through geometric relationship evaluation, assist in the judgment of S5 stress state calculation formula. The stress Mohr circle and the strength curve under different states are as shown in Figure 4 . Figure 4a is the initial state, wherein c w represents the cohesion of the structural plane, and Φ w represents the internal friction angle, C1 represents the tangential stress state, C2 represents the relative stress state, and L represents the strength curve. Figure 4 b is the disturbed state, wherein C(σ x ,τ xy ) represents a point in the disturbed stress state, C'(σ3') represents the minimum principal stress after stress bias conversion in the disturbed state, D'(σ1') represents the maximum principal stress after stress bias conversion in the disturbed state, and D(σ x ,-τ xy ) represents a point in the same disturbed stress state.

[0073] S5. Based on the disturbed stress state, the condition equation of the crack activation and expansion of the rock mass structural plane is derived based on the basic mechanical parameters, and the crack activation damage risk assessment and crack type discrimination of the rock mass are based on the condition equation.

[0074] In this embodiment, the shear slip condition of the structural plane AB is solved based on the stress state, and the normal stress σ' and shear stress τ' on the structural plane AB are solved as follows:

[0075]

[0076] By comprehensively considering the above formula and the stress parameters in the disturbed state, the following is obtained:

[0077]

[0078] Under the influence of the disturbed state, the structural plane AB is activated, the fracture develops and expands to form a crack, and the shear failure behavior of the structural plane AB occurs. The condition equation of the crack activation and expansion of AB based on the Coulomb criterion is as follows:

[0079]

[0080] wherein c w represents the cohesion of the structural plane, represents the internal friction angle of the structural plane, and α represents the stress bias direction of the disturbed state.

[0081] The crack activation damage risk of the rock mass under different states is judged, and the crack type is discriminated. As can be seen from the condition equation, when the maximum principal stress σ'1 increases, the tangential stress τ' of the structural plane AB will also increase, and the crack is more likely to be activated and expanded, and the shear crack s along the structural plane occurs, accompanied by the tensile crack s v and the tensile crack s h in the horizontal direction, as shown in Figure 5 .

[0082] Embodiment Two

[0083] In the embodiment, an evaluation system considering stress deflection induced rock mass crack activation and propagation includes a parameter acquisition module, an initial state calculation module, a perturbation state calculation module, a geometric analysis module and an evaluation module

[0084] The parameter acquisition module is used to acquire basic mechanical parameters of the rock mass to be evaluated and a stress environment thereof.

[0085] The basic mechanical parameters include an elastic modulus, a Poisson's ratio, a cohesion, an internal friction angle and a tensile strength, and the stress environment includes a stress size, a stress direction and an external force perturbation source.

[0086] The initial state calculation module analyzes an initial stress state of the rock mass to be evaluated, constructs an initial state mechanical model of a structural plane, and solves initial state stress parameters.

[0087] In the initial state calculation module, a method for solving the initial state stress parameters includes:

[0088]

[0089] wherein σ represents an initial state normal stress parameter of the structural plane, σ1 represents a maximum initial state principal stress, σ3 represents a minimum initial state principal stress, θ represents an angle between the structural plane and a horizontal direction, and τ represents an initial state tangential stress parameter of the structural plane.

[0090] The perturbation state calculation module is used to analyze an influence of an excavation perturbation source, to perform perturbation stress state analysis, to construct a mechanical analysis model under the influence of the perturbation stress, and to solve perturbation state stress parameters.

[0091] In the perturbation state calculation module, a method for solving the perturbation state stress parameters includes:

[0092]

[0093] l=sinθ, m=cosθ

[0094] σ′ x =σ′3cosθ, σ′ y =σ′1cosθ

[0095] τ′ xy =σ′3sinθ, τ′ yx =-σ′1sinθ

[0096] wherein p x represents a horizontal direction stress component, p y represents a vertical direction stress component, l represents a horizontal direction cosine, m represents a vertical direction cosine, σ′ x represents an x direction stress in the perturbation state, σ′y denotes the perturbed state y-direction stress, τ' xy denotes the perturbed state xy-direction shear stress, τ' yx denotes the perturbed state yx-direction shear stress, σ'1 denotes the perturbed state maximum principal stress, and σ'3 denotes the perturbed state minimum principal stress.

[0097] The geometric analysis module performs geometric analysis of the stress Mohr circle and the strength curve in different states based on the initial stress state and the perturbed stress state.

[0098] The evaluation module derives a condition equation of crack activation and expansion of the rock mass structure surface based on the basic mechanical parameters based on the perturbed stress state, and performs rock mass crack activation damage risk evaluation and crack type discrimination based on the condition equation.

[0099] In the evaluation module, the condition equation includes:

[0100]

[0101] wherein, c w denotes the cohesion of the structure surface, denotes the internal friction angle of the structure surface, and α denotes the perturbed state stress deflection direction.

[0102] The above-described embodiments are merely descriptions of the preferred modes of the present application and do not limit the scope of the present application. Various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.

Claims

1. An evaluation method considering stress deflection induced rock mass crack activation propagation, characterized in that, The method comprises the following steps: obtaining basic mechanical parameters of a rock mass to be evaluated and a stress environment in which the rock mass is located; performing initial stress state analysis on the rock mass to be evaluated, constructing an initial state mechanical model of a structural plane, and solving initial state stress parameters; the method for solving the initial state stress parameters comprises: ； wherein, σ denotes the initial state structure plane normal stress parameter, σ 1 denotes the initial state maximum principal stress, σ 3 denotes the initial state minimum principal stress, θ denotes the angle between the structure plane and the horizontal direction, τ denotes the initial state structure plane tangential stress parameter; performing disturbance stress state analysis, constructing a mechanical analysis model under the influence of disturbance stress, and solving disturbance state stress parameters; the method for solving the disturbance state stress parameters comprises: ； ； ； ； wherein, px denotes the horizontal directional stress component, py denotes the vertical directional stress component, l denotes the horizontal directional cosine, m denotes the vertical directional cosine, denotes the perturbation state x directional stress, denotes the perturbation state y directional stress, denotes the perturbation state xy directional shear stress, denotes the perturbation state yx directional shear stress, denotes the perturbation state maximum principal stress, denotes the perturbation state minimum principal stress; performing geometric analysis of stress Mohr circles and strength curves in different states based on the initial stress state and the disturbance stress state; based on the disturbance stress state, deriving a condition equation of crack activation and expansion of a rock mass structure plane based on the basic mechanical parameters, and performing rock mass crack activation damage risk assessment and crack type discrimination based on the condition equation; the condition equation comprises: ； wherein, cw denotes the cohesion of the structural plane, φw denotes the internal friction angle of the structural plane, α denotes the stress deflection direction of the perturbed state.

2. The method of claim 1, wherein the stress deflection induced rock mass crack activation extension is evaluated by considering, The basic mechanical parameters comprise an elastic modulus, a Poisson's ratio, a cohesion, an internal friction angle, and a tensile strength. The stress environment comprises stress magnitude, stress direction, and external force disturbance sources.

3. An evaluation system considering stress deflection induced activation and propagation of rock mass cracks, said system applying the method of any one of claims 1-2, characterized in that, The method comprises the following steps: a parameter acquisition module, an initial state calculation module, a disturbance state calculation module, a geometric analysis module, and an evaluation module; the parameter acquisition module is configured to obtain basic mechanical parameters of a rock mass to be evaluated and a stress environment in which the rock mass is located; the initial state calculation module is configured to perform initial stress state analysis on the rock mass to be evaluated, construct an initial state mechanical model of a structural plane, and solve initial state stress parameters; the disturbance state calculation module is configured to perform disturbance stress state analysis, construct a mechanical analysis model under the influence of disturbance stress, and solve disturbance state stress parameters; the geometric analysis module is configured to perform geometric analysis of stress Mohr circles and strength curves in different states based on the initial stress state and the disturbance stress state; the evaluation module is configured to derive a condition equation of crack activation and expansion of a rock mass structure plane based on the basic mechanical parameters based on the disturbance stress state, and perform rock mass crack activation damage risk assessment and crack type discrimination based on the condition equation.

4. The evaluation system of claim 3, wherein, The basic mechanical parameters comprise an elastic modulus, a Poisson's ratio, a cohesion, an internal friction angle, and a tensile strength. The stress environment comprises stress magnitude, stress direction, and external force disturbance sources.

5. The evaluation system of claim 4, wherein, In the initial state calculation module, the method for solving the initial state stress parameters comprises: ； wherein, σ denotes the initial state structure plane normal stress parameter, σ 1 denotes the initial state maximum principal stress, σ 3 denotes the initial state minimum principal stress, θ denotes the structure plane and horizontal direction angle, τ denotes the initial state structure plane tangential stress parameter.

6. The evaluation system of claim 5, wherein, In the disturbance state calculation module, the method for solving the disturbance state stress parameters comprises: ； ； ； ； wherein, px denotes the horizontal directional stress component, py denotes the vertical directional stress component, l denotes the horizontal directional cosine, m denotes the vertical directional cosine, denotes the perturbation state x directional stress, denotes the perturbation state y directional stress, denotes the perturbation state xy directional shear stress, denotes the perturbation state yx directional shear stress, denotes the perturbation state maximum principal stress, denotes the perturbation state minimum principal stress.

7. The evaluation system of claim 6, wherein, In the evaluation module, the condition equation comprises: ； wherein, cw denotes the cohesion of the structural plane, φw denotes the internal friction angle of the structural plane, α denotes the stress deflection direction of the perturbed state.

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