A method for designing a support scheme for a roadway by constructing a numerical model

Abstract

The application relates to the technical field of mining engineering, in particular to a method for designing a roadway surrounding rock support scheme by constructing a numerical model, which comprises the following steps: obtaining joint fissure information of a roadway bare rock mass; obtaining an RQD value of a coring drill hole, obtaining basic physical and mechanical parameters of the rock mass; obtaining basic physical and mechanical parameters of the rock mass; constructing an initial block model; adding joint fissures, and cutting the initial block model by using the joint fissures to construct a complex joint rock mass roadway numerical model; assigning parameters to the numerical model; setting boundary conditions for the numerical model, and performing excavation operation; analyzing monitoring data in the excavation operation process, and designing a roadway surrounding rock support scheme. The method combines numerical simulation and field research, simulates non-uniform deformation and failure characteristics of the surrounding rock of a deep roadway under the condition of a non-homogeneous rock mass, is accurate and reliable in numerical calculation, can accurately locate a roadway surrounding rock instability and failure area, and provides a basis for designing a roadway surrounding rock support scheme.

Description

Technical Field

[0001] This invention relates to the field of mining engineering technology, and specifically to a method for designing roadway surrounding rock support schemes by constructing numerical models. Background Technology

[0002] The statements in this section are merely to provide background information related to the technical solutions of this application to aid understanding, and do not necessarily constitute prior art for the technical solutions of this application.

[0003] With the increasing depth of metal mining, the degree of joint and fracture development in the surrounding rock of deep roadways is also increasing. Due to the strong randomness, complex spatial distribution, and diverse morphological distribution of these joints and fractures, construction personnel often make deviations in their stability assessments of the surrounding rock in deep roadways. In severe cases, this can lead to a series of engineering disasters such as large deformation of the surrounding rock and failure of the support structure. Studying the stability of heterogeneous surrounding rock in deep roadways is of significant theoretical importance for safe and efficient mining. However, previous numerical simulation studies often treated fractured rock masses as isotropic homogeneous media, neglecting the influence of joints and fractures on the stability of the surrounding rock in deep roadways, resulting in an inability to accurately predict the deformation and failure of the surrounding rock in deep roadways.

[0004] Currently, the main numerical simulation methods for the stability analysis of surrounding rock in deep tunnels and the design of supporting parameters for surrounding rock are: (1) Finite element method: By splicing mesh elements to form an irregularly shaped research object, its computational efficiency is low and the modeling process is complex, thus it has great limitations in simulating large-scale complex engineering problems. (2) Finite difference method: Using a uniform mesh to divide the solution domain and replacing differential calculation with a small number of discrete point differences, its modeling process is convenient and its computational efficiency is high, and it can also be applied to large-scale complex engineering simulations. However, since both the finite difference method and the finite element method use the continuous medium method for solution, the parameters of joints and fractures in the rock mass need to be defined by the user, which makes it difficult to obtain effective values, thus failing to accurately simulate actual engineering problems and resulting in poor reliability of the calculation results. Summary of the Invention

[0005] To address the above problems, this application provides a method for designing roadway surrounding rock support schemes by constructing a numerical model, including:

[0006] (1) Using a three-dimensional laser scanner and point cloud data processing software, the joint and fracture information of the bare rock mass in the roadway is obtained. The joint and fracture information includes the orientation distribution, area ratio and spatial location information of the joint and fracture.

[0007] (2) Obtain the RQD value of the core drill hole by geological drilling, and prepare standard samples with the extracted rock. Conduct uniaxial compression, Brazilian splitting and variable angle shear tests on the standard samples to obtain the basic physical and mechanical parameters of the rock.

[0008] (3) Based on the RQD value of the core drilling and the joint and fracture information of the bare rock mass in the tunnel, the geological strength index GSI value of the rock mass is determined, and the basic physical and mechanical parameters of the rock obtained are reduced based on the Hoek-Brown strength criterion. Combined with the GSI value, the basic physical and mechanical parameters of the rock mass are obtained.

[0009] (4) Construct the initial block model and build a semi-circular arched tunnel within it;

[0010] (5) Generate new joints and fissures based on the Monte Carlo stochastic simulation method, and use the joints and fissures obtained in step (1) and the new joints and fissures to cut the initial block model into blocks, and construct a numerical model of complex jointed rock mass tunnel.

[0011] (6) The basic physical and mechanical parameters of the rock mass are used to assign parameters to the numerical model of the complex jointed rock mass tunnel;

[0012] (7) Set boundary conditions for the numerical model of the complex jointed rock mass tunnel and perform excavation calculations on the semi-circular arch tunnel in the numerical model of the complex jointed rock mass tunnel.

[0013] (8) Analyze the monitoring data of the numerical model of the complex jointed rock tunnel during the excavation operation, locate the unstable and damaged area of ​​the surrounding rock of the tunnel, and design the support scheme for the surrounding rock of the tunnel.

[0014] In one embodiment, step (1) further includes obtaining the dominant joint and fracture group of the bare rock mass of the tunnel.

[0015] In one embodiment, the standard specimens include a standard cylindrical specimen with a diameter of 50 mm and a height of 100 mm, a standard disk specimen with a diameter of 50 mm and a thickness of 25 mm, and a standard cube specimen with a side length of 50 mm.

[0016] In one embodiment, the geological strength index (GSI) value of the rock mass is determined based on the following formula:

[0017]

[0018] Among them, JCond 89 This represents the joint condition, and its value is determined based on the joint and fracture information of the bare rock mass in the tunnel.

[0019] In one embodiment, when generating the new joints and fissures, the orientation and size of all joints and fissures are always guaranteed to meet the statistical distribution results, and the spatial location of joints and fissures in the bare rock mass of the roadway follows a normal distribution.

[0020] In one embodiment, setting boundary conditions for the numerical model of the complex jointed rock mass tunnel includes: setting fixed displacement boundary conditions around the perimeter and bottom of the numerical model of the complex jointed rock mass tunnel, and setting stress boundary conditions at the top. The stress boundary conditions are determined by measuring the in-situ stress using digital hollow inclusion strain gauge in-situ measurement technology, and a lateral pressure coefficient λ is set to control the application of horizontal stress.

[0021] In one embodiment, the monitoring data includes the deformation of the surrounding rock in the tunnel, the redistribution of stress in the surrounding rock, and the distribution of the plastic zone.

[0022] In one embodiment, the initial block model is constructed using the 3DEC discrete element numerical simulation software.

[0023] In one embodiment, step (1) includes: selecting a bare rock tunnel section after drilling and blasting, using a three-dimensional laser scanner and point cloud data processing software to obtain joint and fracture information of the bare rock mass, wherein the length of the bare rock tunnel section is 2 to 3 m.

[0024] In one embodiment, the Hoek-Brown intensity criterion is a modified Hoek-Brown intensity criterion.

[0025] This method combines numerical simulation and field investigation to simulate the non-uniform deformation and failure characteristics of surrounding rock in deep roadways under heterogeneous rock mass conditions. The numerical calculations are accurate and reliable, providing a basis for asymmetric and zoned support in deep roadways. By using the method described in this application—constructing a numerical model of a roadway with complex jointed rock mass to design roadway surrounding rock support schemes—the constructed numerical model can accurately simulate actual engineering problems, improving the reliability of the numerical simulation results. Furthermore, the numerical calculation results can accurately analyze the non-uniform deformation and failure mechanism of the surrounding rock in deep roadways, precisely locate the unstable failure area of ​​the surrounding rock, and provide a basis for designing roadway surrounding rock support schemes. Attached Figure Description

[0026] The embodiments of the present invention will be further described below with reference to the accompanying drawings, wherein:

[0027] Figure 1 This is a method for designing roadway surrounding rock support schemes by constructing a numerical model of a roadway with complex jointed rock mass, according to one embodiment.

[0028] Figure 2This is a schematic diagram illustrating a method for constructing a numerical model of a complex jointed rock mass tunnel according to one embodiment;

[0029] Figure 3 This is a flowchart illustrating the distribution of joint and fracture orientation in exposed rock mass of deep tunnels based on three-dimensional laser scanning technology, according to one embodiment.

[0030] Figure 4 This is a statistical analysis diagram of the area distribution and orientation of joints and fractures in bare rock mass of a deep tunnel, based on an embodiment.

[0031] Figure 5 This is a distribution diagram of a random joint fracture network after adding joint fractures using a Monte Carlo random simulation method according to an embodiment and importing it into 3DEC discrete element numerical simulation software.

[0032] Figure 6 This is a numerical model diagram of a complex jointed rock mass tunnel based on one embodiment;

[0033] Figure 7 This is a diagram of displacement and deformation in a deep tunnel based on numerical simulation results from one embodiment.

[0034] Figure 8 This is a numerical simulation result of the displacement and stress monitoring of the surrounding rock in a deep tunnel, based on one embodiment. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] Figure 1 This is a method for designing roadway surrounding rock support schemes by constructing a numerical model of a roadway with complex jointed rock mass, based on one embodiment. Now, combined with... Figures 1 to 8 The method is described, and includes the following steps:

[0037] Step 101: Using a 3D laser scanner and point cloud data processing software, obtain joint and fracture information of the bare rock mass in the tunnel. The joint and fracture information includes the orientation distribution, area ratio, and spatial location information of the joints and fractures.

[0038] In one embodiment, a section of bare rock mass tunnel, approximately 2-3 meters in length, is selected after drill-and-blast excavation. A Leica P30 3D laser scanner can be used on-site to perform a 3D laser scan of the bare rock location in the tunnel, obtaining the 3D point cloud spatial distribution of the bare rock mass. Using CloudCompare point cloud data processing software, the 3D point cloud data of the bare rock mass undergoes a series of operations, including filtering and 3D surface reconstruction. Based on the K-tree algorithm built into CloudCompare, the processed 3D point cloud spatial distribution of the bare rock mass is considered to be composed of a series of planar facets; that is, the area size and attitude distribution of the planar facets are regarded as the area size and attitude distribution of the structural surfaces of the bare rock mass. Statistical analysis of the area size and attitude distribution of the structural surfaces of the bare rock mass is performed to obtain joint and fracture information of the bare rock mass in the tunnel. This joint and fracture information includes the attitude distribution, area ratio, and spatial location information of the joints and fractures. In one embodiment, the dominant joint and fracture group of the bare rock mass in the tunnel can also be obtained.

[0039] Step 102: Obtain the RQD value of the core borehole by geological drilling, and prepare a standard sample using the extracted rock. Conduct uniaxial compression, Brazilian splitting and variable angle shear tests on the standard sample to obtain the basic physical and mechanical parameters of the rock.

[0040] In one embodiment, core drilling is performed on-site to measure the RQD (Rock Quality Index) value of each cored borehole. RQD is a general indicator that comprehensively reflects the strength and fracturing degree of the rock mass. The specific calculation method is to divide the cumulative length of rock cores greater than or equal to 10 cm by the length of the cored borehole.

[0041]

[0042] The rock core can then be processed into three sets of standard cylindrical specimens (50 mm in diameter and 100 mm in height), three sets of standard disc specimens (50 mm in diameter and 25 mm in thickness), and fifteen sets of standard cubic specimens (50 mm in side length). Uniaxial compression, Brazilian splitting, and variable-angle shear tests (shear angles of 50°, 55°, 60°, 65°, and 70° can be performed on the processed specimens to obtain the uniaxial compressive strength σ of the rock. c Tensile strength σ t Elastic modulus E, Poisson's ratio μ, cohesion C, angle of internal friction Basic physical and mechanical parameters.

[0043] Step 103: Based on the RQD value of the core drilling and the joint and fracture information of the bare rock mass in the tunnel, determine the geological strength index (GSI) value of the rock mass, and reduce the basic physical and mechanical parameters of the rock obtained based on the Hoek-Brown strength criterion. Combine the GSI value to obtain the basic physical and mechanical parameters of the rock mass.

[0044] In one embodiment, the geological strength index (GSI) value of the rock mass can be determined based on the RQD value of the core borehole and the joint and fracture information of the bare rock mass in the tunnel, according to the following formula.

[0045]

[0046] Among them, joint condition JCond 89 The value is determined based on the joint and fracture information of the bare rock mass in the roadway, such as the length, width, roughness, filling type, and weathering degree of the joints and fractures. Joint condition JCond 89 In the field of geological engineering, the geological strength index (GSI) is a commonly used parameter to describe the state of rock mass structural surfaces, reflecting factors such as surface roughness and alteration. It is a commonly used parameter to measure the strength and stability of geological rocks.

[0047] In one embodiment, the Hoek-Brown strength criterion is an improved or modified version of the Hoek-Brown strength criterion. Based on the modified Hoek-Brown strength criterion, the basic physical and mechanical parameters of the rock obtained from experimental measurements are reduced, and combined with the GSI value, the basic physical and mechanical parameters of the rock mass are obtained, which are then used to assign rock mass strength parameters to the numerical model of complex jointed rock mass tunnels.

[0048] Step 104: Construct the initial block model and build a semi-circular arched tunnel within it.

[0049] In one embodiment, an initial block model can be constructed based on the 3DEC discrete element numerical simulation software, and a semi-circular arched tunnel can be established.

[0050] Step 105: Generate new joints and fissures based on the Monte Carlo stochastic simulation method, and use the joints and fissures obtained in Step 101 and the newly added joints and fissures to cut the initial block model into blocks, thereby constructing a numerical model of a complex jointed rock mass tunnel.

[0051] The number of joints and fissures (original joints and fissures) extracted from the deep tunnel bare rock mass using 3D laser scanning technology in step one may be lower than the actual number. Therefore, new joints and fissures are generated based on the Monte Carlo stochastic simulation method. When generating these new joints and fissures, the orientation, distribution, and size of all joints and fissures are always guaranteed to meet statistical distribution results, wherein the spatial location of the joints and fissures in the tunnel bare rock mass follows a normal distribution.

[0052] In one embodiment, the orientation of joints and fractures in the bare rock mass of the tunnel can be imported in DFN form by compiling the Fish function in the software, and the initial block model can be cut. The built-in Fish functions fracture.ddir, fracture.dip, fracture.pos, and fracture.size control the dip direction, dip angle, spatial location, and size of the joints and fractures, respectively.

[0053] Step 106: Assign parameters to the numerical model of the complex jointed rock mass tunnel using the basic physical and mechanical parameters of the rock mass.

[0054] Step 107: Set boundary conditions for the numerical model of the complex jointed rock mass tunnel, and perform excavation calculations on the semi-circular arch tunnel in the numerical model of the complex jointed rock mass tunnel.

[0055] In one embodiment, fixed displacement boundary conditions can be set around the perimeter and bottom of the numerical model of the complex jointed rock mass tunnel, and stress boundary conditions can be set at the top. The stress boundary conditions are determined by measuring the in-situ stress using digital hollow inclusion strain gauge in-situ measurement technology, and the lateral pressure coefficient λ is set to control the application of horizontal stress.

[0056] After setting boundary conditions, excavation calculations are performed on the semi-circular arched tunnel in the numerical model of the complex jointed rock mass tunnel. The calculation can be stopped when preset conditions are met. In one embodiment, the calculation stops when the maximum unbalanced force of the numerical model of the complex jointed rock mass tunnel is lower than 1e-5.

[0057] Step 108: Analyze the monitoring data of the numerical model of the complex jointed rock tunnel during the excavation calculation, locate the unstable and damaged area of ​​the surrounding rock of the tunnel, and design a support scheme for the surrounding rock of the tunnel.

[0058] In one embodiment, the monitoring data includes the deformation of the surrounding rock, the redistribution of stress in the surrounding rock, and the distribution of the plastic zone. The deformation of the surrounding rock, the redistribution of stress in the surrounding rock, and the distribution of the plastic zone can be analyzed to accurately locate the unstable and damaged areas of the surrounding rock in deep tunnels. This provides a basis for asymmetric support and zoned support of the surrounding rock in tunnels, and ultimately designs a support scheme for the surrounding rock in tunnels.

[0059] Example:

[0060] A section of bare rock mass tunnel, approximately 2-3 meters in length, was selected after drilling and blasting. A Leica P30 3D laser scanner was installed in the middle of the tunnel to acquire 3D spatial point cloud information of the bare rock mass.

[0061] Core drilling was conducted using a φ113mm diameter coreless drill bit. The drilling angle could be 1°–3°, and the drilling length could be 10m, to obtain the RQD (Rock Quality Index) value of the cored borehole. RQD is a general indicator that comprehensively reflects the strength and fracturing degree of rock mass. Specifically, it is calculated by dividing the cumulative length of core samples longer than 10cm by the total borehole length. The extracted core samples were then processed to prepare three sets of standard cylindrical specimens (50mm diameter, 100mm height), three sets of standard disc specimens (50mm diameter, 25mm thickness), and fifteen sets of standard cubic specimens (50mm side length). Uniaxial compression, Brazilian splitting, and variable-angle shear tests were then conducted to obtain the basic physical and mechanical parameters of the rock. The basic physical and mechanical parameters of the rock according to one embodiment are shown in Table 1.

[0062]

[0063] Table 1 Basic physical and mechanical parameters of rocks

[0064] The 3D spatial point cloud coordinates of the bare rock mass acquired by the Leica P30 3D laser scanner were imported into CloudCompare software. Preprocessing steps, including filtering and 3D surface reconstruction, were performed on the point cloud data. Using the software's built-in Kd-tree algorithm, the point cloud distribution after 3D surface reconstruction of the bare rock mass was treated as a series of planar slices, with the dip and dip angle of the slices representing the structural attitude information of the bare rock mass. A total of 600 joints and fractures were extracted from the bare rock mass. The area ratio of the joints and fractures followed an inverse function distribution; the dip direction followed a normal distribution with parameters μ and σ; and the dip angle followed an exponential distribution. The dominant joint fracture groups can be divided into three groups according to their dip direction: 180°–195°, 195°–210°, and 210°–225°, with respective proportions of 9.06%, 13.85%, and 14.88%. According to their strike direction, the dominant joint fracture groups can be divided into two groups: 30°–45° and 120°–135°, with respective proportions of 18.08% and 13.83%. The dip angles of the dominant joint fracture groups are mainly concentrated between 40° and 90°, with respective proportions of 6.12%, 15.27%, 18.98%, 26.29%, and 29.09%.

[0065] Based on the statistical analysis of the orientation, area distribution, filling type, differentiation degree, and roughness of joints and fractures in the bare rock mass, the joint condition JCond is obtained. 89The range of values. The rock quality index RQD obtained from previous geological drilling core samples is used to calculate the geological strength index GSI = 1.5JCond. 89 +0.5RQD.

[0066] The basic physical and mechanical parameters of the rock obtained from the laboratory tests were reduced according to the modified Hoek-Brown strength criterion, and combined with the GSI value to obtain the basic physical and mechanical parameters of the rock mass, which were then used to assign parameters to the material of the numerical model of the complex jointed rock mass tunnel.

[0067] In one embodiment, the relationship between the various physical and mechanical parameters of the rock mass and the geological strength index (GSI) is as follows:

[0068]

[0069] Among them: E m C m , For the elastic modulus, cohesion, and internal friction angle of the rock mass, m b , s and α are rock mass material parameters, and D is the coefficient of the degree of disturbance of the rock mass caused by blasting or stress release.

[0070] Based on the 3DEC discrete element numerical simulation software, an initial block model of 20m×10m×20m was established, and a straight-walled semi-circular arched tunnel with dimensions of 5m×4.5m was set in the middle of the model, wherein the height of the straight wall is 2m and the radius of the arch is 2.5m.

[0071] Since the Leica P30 3D laser extracts a total of 600 rock joints and fissures, which provides limited information about the rock joints and fissures, the number of joints and fissures is increased based on the Monte Carlo stochastic simulation method, while keeping the dip and dip angle of the joints and fissures constant. The location and area of ​​the joints and fissures are changed to make them follow a normal distribution and a negative exponential distribution, and to ensure that the spatial distribution characteristics of the joints and fissures after the increase are consistent with the spatial distribution characteristics of the joints and fissures extracted from the rock in the field.

[0072] By writing the Fish function, the original joints and fractures, as well as newly added joints and fractures, are imported into the 3DEC discrete element numerical simulation software in DFN form. The initial block model is then segmented, with the fracture.ddir, fracture.dip, fracture.pos, and fracture.size functions controlling the dip direction, dip angle, spatial location, and size of the joints and fractures, respectively. Finally, a numerical model of a complex jointed rock mass tunnel is constructed.

[0073] The basic physical and mechanical parameters of the rock mass are used to assign parameters to the numerical model of the complex jointed rock mass tunnel.

[0074] Boundary conditions were set for the numerical model of a complex jointed rock tunnel. Fixed displacement boundary conditions were set at the perimeter and bottom of the numerical model, and stress boundary conditions were set at the top. Based on the in-situ measurement results of the digital hollow inclusion strain gauge, a vertical compressive stress of 32.58 MPa was applied to simulate the gravity of the overlying rock layer. The maximum, intermediate, and minimum principal stresses were parallel to the X, Y, and Z axes, respectively, with lateral pressure coefficients of 1.80 and 1.15, respectively.

[0075] Excavation calculations were performed on the tunnels in the numerical model of complex jointed rock mass tunnels. The calculation was stopped and the results were saved when the maximum unbalanced force of the numerical model was lower than 1e-5.

[0076] Numerical model monitoring data of complex jointed rock tunnels are extracted, including the deformation of the surrounding rock, stress redistribution, and distribution of the plastic zone. The asymmetric deformation and instability failure areas of the surrounding rock in deep tunnels are predicted, and corresponding support schemes are designed.

[0077] References to “various embodiments,” “some embodiments,” “one embodiment,” or “embodiment” throughout this document refer to specific features, structures, or properties described in connection with said embodiments that are included in at least one embodiment. Therefore, the appearance of phrases such as “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment” throughout this document does not necessarily refer to the same embodiment. Furthermore, specific features, structures, or properties can be combined in any suitable manner in one or more embodiments. Therefore, specific features, structures, or properties shown or described in connection with one embodiment can be combined, in whole or in part, with features, structures, or properties of one or more other embodiments without limitation, provided that such combination is not illogical or inoperable. Expressions such as “according to A,” “based on A,” “by A,” or “using A” appearing throughout this document are non-exclusive; that is, “according to A” can cover “according to A only” or “according to A and B,” unless specifically stated otherwise. In this application, some illustrative operational steps are described in a certain order for clarity, but those skilled in the art will understand that each of these operational steps is not essential, and some steps can be omitted or replaced by others. These steps do not necessarily have to be performed sequentially as shown. Instead, some of these steps can be performed in different orders or in parallel as needed, as long as the new execution method is not illogical or ineffective.

[0078] The foregoing descriptions have outlined some exemplary embodiments of the present invention. It is understood that these embodiments are merely illustrative and do not constitute a limitation on the scope of protection of the present invention. Features in these embodiments can be rearranged in suitable ways, and the resulting solutions remain within the scope of protection claimed by the present invention. All other embodiments obtained by those skilled in the art based on the foregoing embodiments without inventive effort, i.e., all modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, fall within the scope of protection claimed by the present invention.

Claims

1. A method for designing roadway surrounding rock support schemes by constructing numerical models, characterized in that, include: (1) Using a three-dimensional laser scanner and point cloud data processing software, the joint and fracture information of the bare rock mass in the roadway is obtained. The joint and fracture information includes the orientation distribution, area ratio and spatial location information of the joint and fracture. (2) Obtain the RQD value of the core drill hole by geological drilling, and prepare standard samples with the extracted rock. Conduct uniaxial compression, Brazilian splitting and variable angle shear tests on the standard samples to obtain the basic physical and mechanical parameters of the rock. (3) Based on the RQD value of the core drilling and the joint and fracture information of the bare rock mass in the tunnel, the geological strength index GSI value of the rock mass is determined, and the basic physical and mechanical parameters of the rock obtained are reduced based on the Hoek-Brown strength criterion. Combined with the GSI value, the basic physical and mechanical parameters of the rock mass are obtained. (4) Construct the initial block model and build a semi-circular arched tunnel within it; (5) Generate new joints and fissures based on the Monte Carlo stochastic simulation method, and use the joints and fissures obtained in step (1) and the new joints and fissures to cut the initial block model into blocks, and construct a numerical model of complex jointed rock mass tunnel. (6) The basic physical and mechanical parameters of the rock mass are used to assign parameters to the numerical model of the complex jointed rock mass tunnel; (7) Set boundary conditions for the numerical model of the complex jointed rock mass tunnel and perform excavation calculations on the semi-circular arch tunnel in the numerical model of the complex jointed rock mass tunnel. (8) Analyze the monitoring data of the numerical model of the complex jointed rock tunnel during the excavation operation, locate the unstable and damaged area of ​​the surrounding rock of the tunnel, and design the support scheme for the surrounding rock of the tunnel.

2. The method according to claim 1, wherein, Step (1) also includes obtaining the dominant joint and fracture groups of the bare rock mass of the tunnel.

3. The method according to claim 1, wherein, The standard specimens include a standard cylindrical specimen with a diameter of 50 mm and a height of 100 mm, a standard disk specimen with a diameter of 50 mm and a thickness of 25 mm, and a standard cube specimen with a side length of 50 mm.

4. The method according to claim 1, wherein, The geological strength index (GSI) value of the rock mass is determined based on the following formula: Among them, JCond 89 This represents the joint condition, and its value is determined based on the joint and fracture information of the bare rock mass in the tunnel.

5. The method according to claim 1, wherein, When generating the new joints and fissures, it is always ensured that the orientation, distribution, and size of all joints and fissures meet the statistical distribution results, and that the spatial location of joints and fissures in the bare rock mass of the roadway follows a normal distribution.

6. The method according to claim 1, wherein, The boundary conditions set for the numerical model of the complex jointed rock mass tunnel include: Fixed displacement boundary conditions are set around the perimeter and bottom of the numerical model of the complex jointed rock mass tunnel, and stress boundary conditions are set at the top. The stress boundary conditions are determined by measuring the in-situ stress using digital hollow inclusion strain gauge in-situ measurement technology, and the lateral pressure coefficient λ is set to control the application of horizontal stress.

7. The method according to claim 1, wherein, The monitoring data includes the deformation of the surrounding rock in the tunnel, the redistribution of stress in the surrounding rock, and the distribution of the plastic zone.

8. The method according to claim 1, wherein, An initial block model was constructed using the 3DEC discrete element numerical simulation software.

9. The method according to claim 1, wherein, Step (1) includes: A section of bare rock mass tunnel after drilling and blasting was selected, and a 3D laser scanner and point cloud data processing software were used to obtain joint and fracture information of the bare rock mass. The length of the bare rock mass tunnel section was 2 to 3 meters.

10. The method according to claim 1, wherein, The Hoek-Brown intensity criterion is a modified Hoek-Brown intensity criterion.

Images