Method for designing roadway surrounding rock supporting scheme by building numerical model

Abstract

The invention relates to the technical field of mining engineering, in particular to a method for designing a roadway surrounding rock supporting scheme by building a numerical model, and the method comprises the following steps: acquiring joint fissure information of a roadway bare rock mass; obtaining the RQD value of the coring drill hole, and obtaining the basic physical and mechanical parameters of the rock; basic physical and mechanical parameters of the rock mass are obtained; constructing an initial block model; joint fissures are newly added, the initial block model is subjected to block cutting through the joint fissures, and a complex jointed rock mass roadway numerical model is constructed; performing parameter assignment on the numerical model; setting boundary conditions for the numerical model, and performing excavation operation; monitoring data in the excavation operation process are analyzed, and a roadway surrounding rock supporting scheme is designed. According to the method, numerical simulation and field investigation are combined, the non-uniform deformation failure characteristics of the surrounding rock of the deep roadway under the non-homogeneous rock mass condition are simulated, numerical calculation is accurate, reliability is high, the roadway surrounding rock instability failure area can be accurately positioned, and a basis is provided for designing a roadway surrounding rock supporting scheme.

Description

Technical Field

[0001] The invention relates to the technical field of mining engineering, and in particular to a method for designing a tunnel surrounding rock support scheme by constructing a numerical model. Background Art

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

[0003] With the increasing mining depth of metal mines, the degree of development of joints and fissures in the surrounding rock of deep tunnels has increased. Due to the strong randomness, complexity of spatial distribution and diversity of morphological distribution of the surrounding rock joints and fissures, the stability evaluation results of the surrounding rock of deep tunnels by construction personnel are often biased, which may cause a series of engineering disasters such as large deformation of the surrounding rock of the tunnel and failure of the supporting structure. The study of the stability of heterogeneous surrounding rock of deep tunnels is of great theoretical significance for the safe and efficient mining of mines. However, since previous numerical simulation studies often regard fractured rock masses as isotropic homogeneous media, the influence of joints and fissures on the stability of the surrounding rock of deep tunnels is ignored, which makes it impossible to accurately predict the deformation and damage of the surrounding rock of deep tunnels.

[0004] At present, the numerical simulation methods for the stability analysis of deep tunnel surrounding rock and the design of tunnel surrounding rock support parameters are mainly: (1) Finite element method: By splicing grid units to form an irregularly shaped research object, its calculation efficiency is low and the modeling process is complicated. Therefore, it has great limitations in simulating large-scale complex engineering problems. (2) Finite difference method: Using uniform grids to divide the solution domain and replacing differential calculations with a small number of discrete point differences, its modeling process is convenient and has high calculation efficiency. 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 to solve, the parameters of the joints and fissures in the rock mass need to be defined by the user, and it is difficult to obtain effective values, so it is impossible to accurately simulate actual engineering problems and the reliability of the calculation results is poor. Summary of the invention

[0005] In view of the above problems, the present application provides a method for designing a tunnel surrounding rock support scheme by constructing a numerical model, including:

[0006] (1) using a three-dimensional laser scanner and point cloud data processing software to obtain joint and fissure information of the bare rock mass of the tunnel, wherein the joint and fissure information includes the occurrence distribution, area proportion and spatial position information of the joint and fissure;

[0007] (2) The RQD value of the coring borehole is obtained by coring the geological borehole, and the standard sample is prepared with the extracted rock. The standard sample is subjected to uniaxial compression, Brazilian splitting and variable angle shear tests to obtain the basic physical and mechanical parameters of the rock;

[0008] (3) According to the RQD value of the core drilling hole and the joint and fissure information of the bare rock mass in the tunnel, the rock mass geological strength index GSI value is determined, and the basic physical and mechanical parameters of the rock obtained are reduced based on the Hoek-Brown strength criterion, and the basic physical and mechanical parameters of the rock mass are obtained by combining the GSI value;

[0009] (4) constructing an initial block model and establishing a semicircular arch tunnel in it;

[0010] (5) generating new joints and fissures based on a Monte-Carlo random simulation method, and using the joints and fissures obtained in step (1) and the new joints and fissures to perform block cutting on the initial block model to construct a numerical model of a complex jointed rock mass tunnel;

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

[0012] (7) setting boundary conditions for the complex jointed rock mass tunnel numerical model, and performing excavation calculations on the semicircular arch tunnel in the complex jointed rock mass tunnel numerical model;

[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 tunnel surrounding rock, and design the tunnel surrounding rock support plan.

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

[0015] In one embodiment, the standard samples include a standard cylindrical sample with a diameter of 50 mm and a height of 100 mm, a standard disc sample with a diameter of 50 mm and a thickness of 25 mm, and a standard cubic sample with a side length of 50 mm.

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

[0017]

[0018] Among them, JCond 89 It represents the joint condition, and its value is determined according to the joint and fissure information of the bare rock mass in the tunnel.

[0019] In one embodiment, when generating the newly added joints and fissures, it is always ensured that the occurrence distribution and size of all joints and fissures satisfy the statistical distribution results, and the spatial positions of the joints and fissures in the bare rock mass of the tunnel obey the normal distribution.

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

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

[0022] In one embodiment, 3DEC discrete element numerical simulation software is used to construct an initial block model.

[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 fissure information of the bare rock mass in the tunnel, wherein the bare rock tunnel section is 2 to 3 meters long.

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

[0025] This method combines numerical simulation with field research to simulate the non-uniform deformation and failure characteristics of the surrounding rock of deep tunnels under heterogeneous rock conditions. The numerical calculation is accurate and reliable, thus providing a basis for asymmetric support and zoning support of deep tunnels. By using the method of designing tunnel surrounding rock support schemes by constructing a complex jointed rock tunnel numerical model of the present application, the constructed complex jointed rock tunnel numerical model can accurately simulate actual engineering problems and improve the reliability of numerical simulation results. In addition, the numerical calculation results can accurately analyze the non-uniform deformation and failure mechanism of the surrounding rock of the deep tunnel, accurately locate the instability and failure area of ​​the tunnel surrounding rock, and provide a basis for designing tunnel surrounding rock support schemes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The embodiments of the present invention are further described below with reference to the accompanying drawings, in which:

[0027] Figure 1 A method for designing a tunnel surrounding rock support scheme by constructing a complex jointed rock tunnel numerical model according to an embodiment;

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

[0029] Figure 3 A flow chart for extracting the occurrence distribution of joints and fissures in bare rock mass in deep tunnels based on three-dimensional laser scanning technology according to an embodiment;

[0030] Figure 4 is a statistical analysis diagram of the distribution of joints and fissures in bare rock mass in a deep tunnel according to an embodiment;

[0031] Figure 5 A random joint and fissure network distribution diagram after adding joints and fissures based on a Monte-Carlo random simulation method and importing into 3DEC discrete element numerical simulation software according to an embodiment;

[0032] Figure 6 is a diagram of a numerical model of a complex jointed rock mass tunnel according to an embodiment;

[0033] Figure 7 is a displacement deformation diagram of a deep tunnel according to a numerical simulation result of an embodiment;

[0034] Figure 8 It is a monitoring diagram of surrounding rock displacement and stress in a deep tunnel according to the numerical simulation results of an embodiment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] Figure 1 A method for designing a tunnel surrounding rock support scheme by constructing a complex jointed rock tunnel numerical model according to an embodiment of the present invention is combined with Figures 1 to 8 The method is described, comprising the following steps:

[0037] Step 101: Using a three-dimensional laser scanner and point cloud data processing software, obtain joint and fissure information of the bare rock mass of the tunnel, wherein the joint and fissure information includes the occurrence distribution, area proportion and spatial position information of the joint and fissure.

[0038] In one embodiment, a bare rock tunnel section after drilling and blasting is selected, with a length of about 2 to 3 meters. A Leica P30 3D laser scanner can be used on site to perform 3D laser scanning on the bare rock position of the tunnel to obtain the 3D point cloud spatial distribution of the bare rock; with the help of CloudCompare point cloud data processing software, a series of operations such as filtering and reconstructing the 3D surface are performed on the 3D point cloud data of the bare rock; based on the K-tree algorithm built into the CloudCompare software, the processed 3D point cloud spatial distribution of the bare rock is regarded as consisting of a series of planar facets, that is, the area size and occurrence distribution of the planar facets are regarded as the structural surface area size and occurrence distribution of the bare rock; the structural surface area size and occurrence distribution of the bare rock are statistically analyzed to obtain the joint and fissure information of the bare rock of the tunnel, and the joint and fissure information includes the occurrence distribution, area proportion and spatial position information of the joint and fissure. In one embodiment, the dominant joint and fissure group of the bare rock of the tunnel can also be obtained.

[0039] Step 102: The RQD value of the coring borehole is obtained by coring the geological borehole, and the extracted rock is used to prepare a standard sample, and uniaxial compression, Brazilian splitting and variable angle shear tests are carried out on the standard sample to obtain basic physical and mechanical parameters of the rock.

[0040] In one embodiment, drilling and coring work is carried out on site, and the RQD (rock quality index) value of each coring borehole is measured. RQD is a general index that comprehensively reflects the strength and degree of rock mass fragmentation. The specific calculation method is the cumulative length of the core greater than or equal to 10 cm divided by the length of the coring borehole.

[0041]

[0042] After that, the core can be processed into 3 groups of standard cylindrical specimens with a diameter of 50 mm and a height of 100 mm, 3 groups of standard disc specimens with a diameter of 50 mm and a thickness of 25 mm, and 15 groups of standard cubic specimens with a side length of 50 mm. The processed specimens are subjected to uniaxial compression, Brazilian splitting, and variable angle shear tests (the shear angle can be set to 50°, 55°, 60°, 65°, and 70°) to obtain the uniaxial compressive strength σ of the rock. c , tensile strength σ t , elastic modulus E, Poisson's ratio μ, cohesion C, internal friction angle And other basic physical and mechanical parameters.

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

[0044] In one embodiment, the rock mass geological strength index GSI value may be determined based on the following formula according to the RQD value of the core drilling hole and the joint and fissure information of the bare rock mass in the tunnel.

[0045]

[0046] Among them, the joint condition JCond 89 The value of is determined according to the joint and fissure information of the bare rock mass of the roadway, such as the length, width, roughness, filling type and weathering degree of the joint and fissure. 89 It is a commonly used parameter in the field of geological engineering to describe the state of rock mass structural surface, which reflects factors such as the roughness and alteration of the structural surface. Geological Strength Index (GSI) 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 Hoek-Brown strength criterion. Based on the modified Hoek-Brown strength criterion, the basic physical and mechanical parameters of the rock obtained from the test measurement are reduced, and combined with the GSI value, the basic physical and mechanical parameters of the rock mass are obtained, which are used for the subsequent rock mass strength parameter assignment of the complex jointed rock mass tunnel numerical model.

[0048] Step 104: construct an initial block model and establish a semicircular arch tunnel therein.

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

[0050] Step 105: Generate new joints and fissures based on the Monte-Carlo random simulation method, and use the joints and fissures obtained in step 101 and the new joints and fissures to perform block cutting on the initial block model to construct a numerical model of a complex jointed rock tunnel.

[0051] In step 1, the number of joints and fissures (original joints and fissures) of the bare rock mass of the deep tunnel extracted by the three-dimensional laser scanning technology may be lower than the actual number. Therefore, based on the Monte-Carlo random simulation method, new joints and fissures are generated. When generating the new joints and fissures, it is always ensured that the occurrence distribution and size of all joints and fissures meet the statistical distribution results, wherein the spatial position of the joints and fissures of the bare rock mass of the tunnel obeys the normal distribution.

[0052] In one embodiment, the occurrence of joints and fissures in the bare rock mass of the tunnel can be imported in the form of DFN by compiling the Fish function in the software, and the initial block model can be cut, wherein the built-in Fish functions fracture.ddir, fracture.dip, fracture.pos, and fracture.size in the software respectively control the inclination, dip, spatial position, and size of the joints and fissures.

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

[0054] Step 107: setting boundary conditions for the complex jointed rock mass tunnel numerical model, and performing excavation operations on the semicircular arch tunnel in the complex jointed rock mass tunnel numerical model.

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

[0056] After setting the boundary conditions, the semicircular arch type roadway in the complex jointed rock mass roadway numerical model is excavated. When the preset conditions are met, the operation can be stopped. In one embodiment, when the maximum unbalanced force of the complex jointed rock mass roadway numerical model is lower than 1e-5, the operation is stopped.

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

[0058] In one embodiment, the monitoring data includes the deformation of the tunnel surrounding rock, the redistribution of surrounding rock stress and the distribution of plastic zone. The deformation of the tunnel surrounding rock, the redistribution of surrounding rock stress and the distribution of plastic zone can be analyzed to accurately locate the unstable and damaged areas of the deep tunnel surrounding rock, provide a basis for asymmetric support and zoned support of the tunnel surrounding rock, and finally design a tunnel surrounding rock support plan.

[0059] Example:

[0060] A bare rock tunnel section after drilling and blasting was selected, with a length of about 2 to 3 m. A Leica P30 3D laser scanner was set up in the middle of the tunnel to obtain the 3D spatial point cloud information of the bare rock mass in the tunnel.

[0061] A coreless drill with a diameter of φ113mm is used for on-site geological drilling and coring work. The drilling inclination angle can be 1°~3°, and the drilling length can be 10m to obtain the RQD (rock quality index) value of the coring borehole. RQD is a general indicator that comprehensively reflects the strength of the rock mass and the degree of rock mass fragmentation. The specific calculation method is the cumulative length of the core greater than 10cm divided by the total drilling length. Afterwards, the taken out core is processed to make 3 groups of standard cylindrical samples with a diameter of 50mm and a height of 100mm, 3 groups of standard disc samples with a diameter of 50mm and a thickness of 25mm, and 15 groups of standard cubic samples with a side length of 50mm. Uniaxial compression, Brazilian splitting and variable angle shear experiments of rocks are carried out respectively to obtain the basic physical and mechanical parameters of rocks. The basic physical and mechanical parameters of rocks according to one embodiment are shown in Table 1.

[0062]

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

[0064] The three-dimensional point cloud coordinates of the bare rock mass obtained by the Leica P30 three-dimensional laser scanner were imported into the CloudCompare software, and the point cloud data was pre-processed by filtering and reconstructing the 3D surface. The Kd-tree algorithm provided by the software was used to regard the point cloud distribution after the 3D surface of the bare rock mass was reconstructed as a series of plane slices, and the inclination and dip angle of the slices were regarded as the structural surface occurrence information of the bare rock mass. A total of 600 joints and fissures of the bare rock mass were extracted, among which the area proportion of the joints and fissures obeyed the inverse function distribution; the inclination obeyed the normal distribution with parameters μ and σ; and the dip angle obeyed the exponential distribution. The dominant joints and fissures can be divided into three groups according to their dip distribution, namely 180°~195°, 195°~210° and 210°~225°, accounting for 9.06%, 13.85% and 14.88% of their respective numbers. The dominant joints and fissures can be divided into two groups according to their strike, namely 30°~45° and 120°~135°, accounting for 18.08% and 13.83% of their respective numbers. The dip angles of the dominant joints and fissures are mainly concentrated between 40° and 90°, accounting for 6.12%, 15.27%, 18.98%, 26.29% and 29.09% of their respective numbers.

[0065] According to the statistical occurrence, area distribution, filling type, differentiation degree and roughness of bare rock joints, the joint condition JCond 89The value range of the rock quality index RQD obtained by the previous geological drilling core sampling is solved by the formula of geological strength index GSI=1.5JCond 89 +0.5RQD.

[0066] The basic physical and mechanical parameters of the rock obtained from the indoor test were reduced according to the modified Hoek-Brown strength criterion, and combined with the GSI value, the basic physical and mechanical parameters of the rock mass were obtained, which were used for the subsequent material parameter assignment of the numerical model of the complex jointed rock mass tunnel.

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

[0068]

[0069] Where: E m , C m , is the elastic modulus, cohesion and internal friction angle of the rock mass, m b , s and α are rock 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 3DEC discrete element numerical simulation software, an initial block model of 20m×10m×20m was established, and a straight-wall semicircular arch tunnel with a size of 5m×4.5m was set in the middle of the model, where the straight wall height was 2m and the arch radius was 2.5m.

[0071] Since the number of surrounding rock joints and fissures extracted by Leica P30 three-dimensional laser is 600 in total, the information reflected by the joints and fissures of the surrounding rock is limited. Therefore, based on the surrounding rock joints and fissures extracted on site, the number of joints and fissures is increased based on the Monte-Carlo random simulation method, the inclination and dip of the joints and fissures are kept unchanged, the position and area of ​​the joints and fissures are changed to make them obey the normal distribution and negative exponential distribution, and the spatial distribution characteristics of the joints and fissures after the increase are ensured to be consistent with the spatial distribution characteristics of the joints and fissures of the surrounding rock extracted on site.

[0072] By writing the Fish function, the original joints and fissures and the newly added joints and fissures are imported into the 3DEC discrete element numerical simulation software in the form of DFN, and the initial block model is cut. The fracture.ddir, fracture.dip, fracture.pos, and fracture.size functions are used to control the inclination, dip, spatial position, and size of the joints and fissures. 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 are set for the numerical model of complex jointed rock tunnels, where fixed displacement boundary conditions are set around and at the bottom of the numerical model, and stress boundary conditions are set at the top. According to the in-situ measurement technology results of the digital hollow body strain gauge, a vertical compressive stress of 32.58MPa is applied to simulate the gravity of the unestablished overlying rock layer. The maximum, intermediate, and minimum principal stresses are parallel to the X, Y, and Z axes, respectively, and the lateral pressure coefficients are 1.80 and 1.15, respectively.

[0075] The excavation calculation of the tunnel in the complex jointed rock tunnel numerical model is carried out. When the maximum unbalanced force of the numerical model is lower than 1e-5, the calculation is stopped and the calculation results are saved.

[0076] The monitoring data of the numerical model of complex jointed rock tunnels, including the deformation of the tunnel surrounding rock, the redistribution of surrounding rock stress and the distribution of plastic zones, are extracted to predict the asymmetric deformation, instability and failure areas of the surrounding rock of deep tunnels, and the corresponding support scheme design is proposed.

[0077] References herein to "various embodiments", "some embodiments", "one embodiment" or "an embodiment" etc. refer to that a particular feature, structure or property described in conjunction with the embodiment is included in at least one embodiment. Therefore, the phrases "in various embodiments", "in some embodiments", "in one embodiment" or "in an embodiment" etc. appearing throughout this document do not necessarily refer to the same embodiment. In addition, particular features, structures or properties may be combined in any suitable manner in one or more embodiments. Therefore, the particular features, structures or properties shown or described in conjunction with one embodiment may be combined in whole or in part with features, structures or properties of one or more other embodiments without restriction, as long as the combination is not illogical or inoperable. Expressions similar to "according to A", "based on A", "through A" or "using A" appearing herein are intended to be non-exclusive, that is, "according to A" may cover "according to A only" or "according to A and B", unless it is specifically stated that its meaning is "according to A only". In this application, for the sake of clarity, some exemplary operating steps are described in a certain order, but those skilled in the art will understand that each of these operating steps is not essential, and some of the steps may be omitted or replaced by other steps. These operation steps do not have to be executed sequentially in the manner shown; on the contrary, some of these operation steps can be executed in different orders or in parallel according to actual needs, as long as the new execution manner is not illogical or inoperable.

[0078] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the scheme obtained thereby is still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without making creative work, that is, all modifications, equivalent substitutions and improvements made within the spirit and principles of this application, fall within the protection scope required by the present invention.

Claims

1. A method for designing a tunnel surrounding rock support scheme by constructing a numerical model, characterized in that: include: (1) using a three-dimensional laser scanner and point cloud data processing software to obtain joint and fissure information of the bare rock mass of the tunnel, wherein the joint and fissure information includes the occurrence distribution, area proportion and spatial position information of the joint and fissure; (2) The RQD value of the coring borehole is obtained by coring the geological borehole, and the standard sample is prepared with the extracted rock. The standard sample is subjected to uniaxial compression, Brazilian splitting and variable angle shear tests to obtain the basic physical and mechanical parameters of the rock; (3) According to the RQD value of the core drilling hole and the joint and fissure information of the bare rock mass in the tunnel, the rock mass geological strength index GSI value is determined, and the basic physical and mechanical parameters of the rock obtained are reduced based on the Hoek-Brown strength criterion, and the basic physical and mechanical parameters of the rock mass are obtained by combining the GSI value; (4) constructing an initial block model and establishing a semicircular arch tunnel in it; (5) generating new joints and fissures based on a Monte-Carlo random simulation method, and using the joints and fissures obtained in step (1) and the new joints and fissures to perform block cutting on the initial block model to construct a numerical model of a complex jointed rock mass tunnel; (6) using the basic physical and mechanical parameters of the rock mass to assign parameters to the numerical model of the complex jointed rock mass tunnel; (7) setting boundary conditions for the complex jointed rock mass tunnel numerical model, and performing excavation calculations on the semicircular arch tunnel in the complex jointed rock mass tunnel numerical model; (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 tunnel surrounding rock, and design the tunnel surrounding rock support plan.

2. The method according to claim 1, wherein: The step (1) also includes obtaining a dominant joint and fissure group of the bare rock mass of the tunnel.

3. The method according to claim 1, wherein: The standard samples include a standard cylindrical sample with a diameter of 50 mm and a height of 100 mm, a standard disc sample with a diameter of 50 mm and a thickness of 25 mm, and a standard cubic sample with a side length of 50 mm.

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

5. The method according to claim 1, wherein: When generating the newly added joints and fissures, it is always ensured that the occurrence distribution and size of all joints and fissures meet the statistical distribution results, and the spatial positions of the joints and fissures in the bare rock mass of the tunnel obey the normal distribution.

6. The method according to claim 1, wherein: The boundary conditions for the complex jointed rock mass tunnel numerical model are set as follows: Fixed displacement boundary conditions are set around and at the bottom of the complex jointed rock tunnel numerical model, and stress boundary conditions are set at the top. The stress boundary conditions are determined by measuring the on-site ground stress using the in-situ measurement technology of the digital hollow inclusion strain gauge, 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 include tunnel surrounding rock deformation, surrounding rock stress redistribution and plastic zone distribution.

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

9. The method according to claim 1, wherein: The step (1) comprises: A bare rock tunnel section after drilling and blasting is selected, and joint and fissure information of the bare rock mass of the tunnel is obtained by using a three-dimensional laser scanner and point cloud data processing software. The bare rock tunnel section is 2 to 3 meters long.

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

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