Method for constructing deep surrounding rock-fluidized medium collaborative bearing mechanical model

Abstract

The application discloses a deep surrounding rock-fluidized medium collaborative bearing mechanical model construction method, which comprises the following steps: S1, constructing a surrounding rock nonlinear strength model: based on the generalized Hoek-Brown criterion, introducing a confining pressure-plastic shear strain negative exponential function relationship, and establishing a deep surrounding rock nonlinear strength criterion considering post-peak softening characteristics; S2, establishing a fluidized medium constitutive model: obtaining viscoelastic parameters of a grouting body through indoor rheological test, and the application relates to the field of underground engineering mechanics. The deep surrounding rock-fluidized medium collaborative bearing mechanical model construction method can more accurately describe the mechanical behavior in the deep surrounding rock-fluidized medium collaborative bearing process by establishing a mechanical model considering the post-peak softening characteristics of surrounding rock, the rheological characteristics of fluidized medium and the nonlinear behavior of an interface, greatly improves the accuracy and reliability of the calculation results compared with traditional models, and provides a more reliable theoretical basis for deep underground engineering stability analysis.

Description

Technical Field

[0001] This invention relates to the field of underground engineering mechanics, specifically to a method for constructing a collaborative bearing mechanics model of deep surrounding rock and fluidized medium. Background Technology

[0002] In the process of deep underground engineering construction and resource extraction, as the mining depth continues to increase, the deep surrounding rock is in a complex environment of high ground stress, high osmotic pressure and high temperature. Its mechanical behavior exhibits significant nonlinearity, discontinuity and time correlation. Traditional surrounding rock mechanics models are difficult to accurately describe the deformation and failure process of deep surrounding rock under complex conditions. In particular, when the surrounding rock undergoes fluidization, the interaction between the surrounding rock and the fluidized medium makes the mechanical behavior more complex.

[0003] Existing research has several shortcomings in constructing mechanical models for the collaborative bearing capacity of deep surrounding rock and fluidized media. For example, the description of the strength characteristics of the surrounding rock does not fully consider the post-peak softening process; the constitutive relationship of the fluidized media is not accurately described, failing to adequately reflect its rheological properties such as shear thinning; and when dealing with the contact interface between the surrounding rock and the fluidized media, there is a lack of effective theories and methods to describe the nonlinear behavior and damage evolution process of the interface. Furthermore, existing numerical calculation methods and platforms are difficult to implement multi-physics coupling analysis in simulating the collaborative bearing capacity of deep surrounding rock and fluidized media, failing to meet the actual needs of complex working conditions in deep underground engineering. Therefore, this invention provides a method for constructing a mechanical model for the collaborative bearing capacity of deep surrounding rock and fluidized media. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for constructing a collaborative bearing mechanics model of deep surrounding rock and fluidized medium. This method solves the problem that traditional surrounding rock mechanics models are unable to accurately describe the deformation and failure process of deep surrounding rock under complex conditions in deep underground engineering, especially the complex mechanical behavior when the surrounding rock interacts with the fluidized medium. This includes the existing models' insufficient description of the softening of the surrounding rock after the peak, the rheological properties of the fluidized medium, and the nonlinear behavior of the interface, as well as the difficulty of numerical calculation methods and platforms in realizing multi-physics coupling analysis.

[0005] To achieve the above objectives, the present invention provides a method for constructing a collaborative bearing capacity mechanical model of deep surrounding rock and fluidized medium, comprising the following steps:

[0006] S1. Constructing a nonlinear strength model for surrounding rock: Based on the generalized Hoek-Brown criterion, a negative exponential function relationship between confining pressure and plastic shear strain is introduced to establish a nonlinear strength criterion for deep surrounding rock that considers post-peak softening characteristics.

[0007] S2, establishing a fluidized medium constitutive model: obtaining viscoelastic parameters of grouting body through indoor rheological test, and combining with Bingham fluid model to describe shear thinning characteristics thereof;

[0008] S3, defining a contact nonlinear interface: based on fractal geometry theory, establishing roughness-bonding strength relationship of surrounding rock-medium interface, and introducing a damage factor to describe interface debonding process;

[0009] S4, constructing a cooperative bearing mechanical model: regarding surrounding rock, fluidized medium and interface as a unified system, and solving stress-strain field distribution through elastic-plastic contact iteration algorithm;

[0010] S5, developing a numerical calculation platform: based on ABAQUS / UMAT interface, realizing parameterized input and dynamic simulation of the model;

[0011] The nonlinear strength model of the surrounding rock satisfies:

[0012] ,

[0013] wherein, , is a principal stress, is uniaxial compressive strength of intact rock, , is a rock integrity coefficient, is a softening coefficient, is a plastic shear strain;

[0014] The fluidized medium constitutive model satisfies:

[0015] ,

[0016] wherein, is a shear stress, is a yield stress, is a plastic viscosity, is a shear rate, , are rheological parameters;

[0017] The contact nonlinear interface satisfies:

[0018] ,

[0019] wherein, is an interface shear strength, is an interface cohesion and friction angle, is a damage factor, .

[0020] Preferably, the elastic-plastic contact iterative algorithm comprises: initial stress field assignment, surrounding rock plastic zone expansion judgment, medium rheological displacement update, interface contact force iterative solution and convergence criterion:

[0021] ,

[0022] Wherein, is the maximum contact force increment, is the maximum contact force, is the convergence accuracy.

[0023] Preferably, the numerical calculation platform supports multi-physical field coupling, including:

[0024] a, thermal-mechanical coupling: considering the influence of temperature field on medium solidification during grouting process;

[0025] b, seepage-stress coupling: based on Biot theory to describe the weakening effect of pore water pressure on effective stress of surrounding rock.

[0026] Preferably, the model parameter calibration needs to be obtained through the following tests:

[0027] c, surrounding rock: rock uniaxial compressive strength test, triaxial compression test, Brazilian splitting test;

[0028] d, medium: wave velocity test, rheometer shear test, curing time-strength curve test;

[0029] e, interface: direct shear test, laser scanning roughness measurement, structure surface observation, borehole RQD measurement.

[0030] Preferably, the model is suitable for deep engineering with buried depth ≥800m and ground stress ≥20MPa, and the solidification time of fluidized medium is ≤24h and the compressive strength is ≥5MPa.

[0031] Beneficial effects

[0032] The application provides a deep surrounding rock-fluidized medium cooperative bearing mechanical model construction method. Compared with the prior art, the following beneficial effects are possessed:

[0033] 1、The deep surrounding rock-fluidized medium cooperative bearing mechanical model construction method can more accurately describe the mechanical behavior in the deep surrounding rock-fluidized medium cooperative bearing process by establishing a mechanical model considering the post-peak softening characteristics of surrounding rock, the rheological characteristics of fluidized medium and the nonlinear behavior of interface, and greatly improves the accuracy and reliability of the calculation results compared with traditional models, and provides a more reliable theoretical basis for stability analysis of deep underground engineering.

[0034] 2、The deep surrounding rock-fluidized medium collaborative bearing mechanical model construction method can truly simulate complex physical processes in deep underground engineering, such as the influence of temperature change on medium solidification in the grouting process and the influence of groundwater seepage on the stress state of surrounding rock, and the simulation result is more in line with the actual engineering situation, thereby providing more comprehensive technical support for engineering design and construction.

[0035] 3、The deep surrounding rock-fluidized medium collaborative bearing mechanical model construction method is suitable for deep engineering under specific conditions (burial depth ≥800 m, ground stress ≥20 MPa, fluidized medium solidification time ≤24 h, and compressive strength ≥5 MPa), can accurately analyze the characteristics of such engineering, has strong practicability, helps to improve the scientificity of deep underground engineering design and construction, reduces engineering risk, and saves engineering cost. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The deep surrounding rock-fluidized medium collaborative bearing mechanical model construction method of the application is provided. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0038] Please refer to Figure 1 The application provides a technical solution:

[0039] The deep surrounding rock-fluidized medium collaborative bearing mechanical model construction method comprises the following steps:

[0040] S1, constructing a surrounding rock nonlinear strength model: based on the generalized Hoek-Brown criterion, introducing a confining pressure-plastic shear strain negative exponential function relationship, establishing a deep surrounding rock nonlinear strength criterion considering post-peak softening characteristics;

[0041] The criterion can more accurately describe the strength change of deep surrounding rock under complex stress states, especially the softening behavior in the post-peak stage, and provides a more reliable theoretical basis for analyzing the deformation and failure of surrounding rock.

[0042] S2, establishing a fluidized medium constitutive model: obtaining viscoelastic parameters of grouting body through indoor rheological test, and combining a Bingham fluid model to describe the shear thinning characteristics;

[0043] The constitutive model can accurately reflect the mechanical response of fluidized medium under different shear rates, and provides a reasonable mathematical description for simulating the flow and bearing process of fluidized medium.

[0044] S3, define the contact nonlinear interface: based on the fractal geometry theory, establish the roughness-bond strength relationship of the surrounding rock-medium interface, and introduce the damage factor to describe the interface debonding process;

[0045] Through this method, the nonlinear behavior and damage evolution of the interface can be effectively considered, and the interaction process between the surrounding rock and the fluidized medium can be accurately simulated.

[0046] S4, build a collaborative bearing mechanical model: the surrounding rock, fluidized medium and interface are regarded as a unified system, and the stress-strain field distribution is solved by the elastic-plastic contact iteration algorithm;

[0047] This algorithm can comprehensively consider the mechanical properties of surrounding rock, fluidized medium and interface, and accurately calculate the mechanical behavior of the whole collaborative bearing system.

[0048] S5, develop a numerical calculation platform: based on the ABAQUS / UMAT interface, realize the parameterization input and dynamic simulation of the model;

[0049] The nonlinear strength model of surrounding rock satisfies:

[0050] ,

[0051] Where, , is the principal stress, is the uniaxial compressive strength of intact rock, , is the intact coefficient of rock mass, is the softening coefficient, is the plastic shear strain;

[0052] The constitutive model of fluidized medium satisfies:

[0053] ,

[0054] Where, is the shear stress, is the yield stress, is the plastic viscosity, is the shear rate, , is the rheological parameter;

[0055] The contact nonlinear interface satisfies:

[0056] ,

[0057] wherein, is the interface shear strength, is the interface cohesion and friction angle, is the damage factor, .

[0058] The numerical calculation platform supports multi-physical field coupling, including thermal-mechanical coupling for considering the influence of the temperature field of the grouting process on the curing of the medium, and seepage-stress coupling based on the Biot theory to describe the weakening effect of pore water pressure on the effective stress of the surrounding rock, so that the complex working conditions of deep underground engineering can be simulated more truly.

[0059] In the embodiment of the application, the elastic-plastic contact iteration algorithm comprises: initial stress field assignment, surrounding rock plastic zone expansion judgment, medium rheological displacement updating, interface contact force iteration solving and convergence criterion:

[0060] ,

[0061] wherein, is the maximum contact force increment, is the maximum contact force, is the convergence precision.

[0062] In the embodiment of the application, the numerical calculation platform supports multi-physical field coupling, including:

[0063] a. Thermal-mechanical coupling: considering the influence of the temperature field of the grouting process on the curing of the medium;

[0064] b. Seepage-stress coupling: based on the Biot theory to describe the weakening effect of pore water pressure on the effective stress of the surrounding rock.

[0065] By establishing the relationship between temperature and the mechanical properties of the medium, thermal-mechanical coupling analysis is realized, and the change of the mechanical properties of the medium in the grouting process is accurately simulated.

[0066] By establishing the coupling relationship between the seepage equation and the stress equation, seepage-stress coupling analysis is realized, and the influence of groundwater on the stability of the surrounding rock is considered.

[0067] In the embodiment of the application, the model parameter calibration needs to be obtained through the following tests:

[0068] c. Surrounding rock: rock uniaxial compressive strength test, triaxial compression test, Brazilian splitting test;

[0069] d. Medium: wave velocity test, rheometer shear test, curing time-strength curve test;

[0070] e. Interface: direct shear test, laser scanning roughness measurement, structure surface observation, borehole RQD measurement.

[0071] Triaxial compression test, Brazilian splitting test are carried out, and the mechanical parameters of the surrounding rock such as elastic modulus, Poisson's ratio, compressive strength, tensile strength and the like are obtained, so as to determine the parameters in the nonlinear strength model of the surrounding rock;

[0072] Rheometer shear test, curing time-strength curve test are carried out, and the viscoelastic parameters, yield stress, plastic viscosity and the like of the fluidized medium are obtained, and the variation law of the strength of the medium with time in the curing process is obtained, so as to establish the constitutive model of the fluidized medium;

[0073] Direct shear test, laser scanning roughness measurement are carried out, and the cohesion, friction angle, roughness and the like of the interface are obtained, so as to define the contact nonlinear interface.

[0074] In the embodiment of the application, the model is applicable to deep engineering with a buried depth of greater than or equal to 800 m and a ground stress of greater than or equal to 20 MPa, and the fluidized medium has a curing time of less than or equal to 24 h and a compressive strength of greater than or equal to 5 MPa.

[0075] In summary:

[0076] By establishing the mechanical model considering the post-peak softening characteristics of the surrounding rock, the rheological characteristics of the fluidized medium and the nonlinear behavior of the interface, and developing the corresponding numerical calculation platform, the accurate simulation of the cooperative bearing process of the deep surrounding rock-fluidized medium is realized, and more accurate and effective theoretical tools and technical means are provided for the stability analysis and support design of the deep underground engineering.

[0077] Meanwhile, the contents not described in detail in the specification all belong to the prior art known by those skilled in the art.

[0078] It should be noted that, in this paper, relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0079] Although the embodiments of the application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the application, and the scope of the application is defined by the appended claims and their equivalents.

Claims

1. A method for constructing a collaborative bearing capacity mechanical model of deep surrounding rock and fluidized medium, characterized in that, Includes the following steps: S1. Constructing a nonlinear strength model for surrounding rock: Based on the generalized Hoek-Brown criterion, a negative exponential function relationship between confining pressure and plastic shear strain is introduced to establish a nonlinear strength criterion for deep surrounding rock that considers post-peak softening characteristics. S2. Establish constitutive model of fluidized medium: obtain viscoelastic parameters of grout body through indoor rheological tests, and describe its shear thinning characteristics in combination with Bingham fluid model; S3. Define the nonlinear contact interface: Based on fractal geometry theory, establish the roughness-bond strength relationship of the surrounding rock-medium interface, and introduce a damage factor to describe the interface debonding process. S4. Construct a collaborative bearing mechanics model: Treat the surrounding rock, fluidized medium and interface as a unified system, and solve the stress-strain field distribution through an elastoplastic contact iterative algorithm; S5. Develop a numerical computing platform: Based on the ABAQUS / UMAT interface, realize model parameterization input and dynamic simulation; The nonlinear strength model of the surrounding rock satisfies: ， in, , Principal stress, The uniaxial compressive strength of intact rock. , The rock mass integrity coefficient. The softening coefficient is... For plastic shear strain; The constitutive model of the fluidized medium satisfies: ， in, For shear stress, For yield stress, To achieve plastic viscosity, For shear rate, , These are rheological parameters; The contact nonlinear interface satisfies: ， in, For the interfacial shear strength, For interfacial cohesion and friction angle, As a damage factor, .

2. The method for constructing a deep surrounding rock-fluidized medium co-bearing mechanical model according to claim 1, characterized in that: The elastoplastic contact iterative algorithm includes: initial stress field assignment, determination of plastic zone expansion in surrounding rock, updating of medium rheological displacement, iterative solution of interface contact force, and convergence criterion. ， in, For the maximum contact force increment, For maximum contact force, For convergence accuracy.

3. The method for constructing a deep surrounding rock-fluidized medium co-bearing mechanical model according to claim 1, characterized in that: The numerical computation platform supports multiphysics coupling, including: a. Thermo-mechanical coupling: Considering the influence of the temperature field on the curing of the medium during the grouting process; b. Seepage-stress coupling: Based on Biot theory, this describes the weakening effect of pore water pressure on the effective stress of the surrounding rock.

4. The method for constructing a deep surrounding rock-fluidized medium co-bearing mechanical model according to claim 1, characterized in that: The model parameters need to be calibrated through the following experiments: c. Surrounding rock: Uniaxial compressive strength test, triaxial compression test, Brazilian splitting test; d. Medium: Wave velocity test, rheometer shear test, curing time-strength curve test; e. Interface: Direct shear test, laser scanning roughness measurement, structural surface observation, borehole RQD measurement.

5. The method for constructing a deep surrounding rock-fluidized medium co-bearing mechanical model according to claim 1, characterized in that: The model is applicable to deep engineering projects with a burial depth ≥ 800m and ground stress ≥ 20MPa, and the fluidized medium has a curing time ≤ 24h and a compressive strength ≥ 5MPa.

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