A rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones

Abstract

This invention provides a rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones, belonging to the field of deep-buried tunnel surrounding rock technology. The method first constructs a numerical method for the stress distribution within the loosened zone of the surrounding rock in deep-buried tunnels based on in-situ acquired surrounding rock parameters, and an analytical method for the stress distribution outside the loosened zone of the surrounding rock in high tectonic stress zones. Then, it proposes a method for evaluating the range of the loosened zone by integrating numerical and analytical methods. Finally, it rapidly predicts the maximum thickness of the loosened zone using two dimensionless factors that reflect the characteristics of high tectonic stress. This invention targets deep-buried tunnels in high tectonic stress zones along the Sichuan-Tibet Railway, adopting the concept of integrated digital-numerical analysis for deep rock engineering. It combines the inherent advantages of prior analytical methods in rapid calculation, developing an analytical method that balances the accuracy and speed requirements of engineering calculations to meet the significant needs of dynamic design and three-dimensional forward analysis of surrounding rock stability in deep-buried tunnel engineering.

Description

Technical Field

[0001] This invention belongs to the field of deep-buried tunnel surrounding rock technology, and particularly relates to a rapid quantitative evaluation method for the stability of deep-buried tunnel surrounding rock in high tectonic stress zones. Background Technology

[0002] The Sichuan-Tibet Railway traverses the Qinghai-Tibet Plateau, a region formed by the collision and uplift of the Indian and Eurasian plates. The route primarily lies in the areas where the eastward extrusion of the Qinghai-Tibet Plateau is most intense. The strong and frequent geological tectonic activity has created a geostress environment with particularly prominent horizontal tectonic stress, posing unprecedented challenges to the construction of the Sichuan-Tibet Railway. The railway includes a large number of ultra-long, deep-buried tunnels under construction or planned in high tectonic stress zones. The excavation and unloading of these tunnels can easily induce a series of engineering disasters, such as sudden rock bursts, severe brittle failure, and continuous large deformations. The geological safety risks posed to the construction and even the entire life cycle of these tunnels cannot be ignored. Therefore, scientifically evaluating the stability of the surrounding rock of deep-buried tunnels in high tectonic stress zones is not only a prerequisite for tunnel construction but also the foundation for tunnel disaster prevention and control, and is of great significance to the Sichuan-Tibet Railway.

[0003] The thickness of the loosened zone in the surrounding rock after deep tunnel excavation can provide a quantitative reference for evaluating the stability of the surrounding rock. In tunnel design, the support structure design can be initially given based on the pre-determined loosened zone thickness. Then, during construction, the thickness of the loosened zone in the surrounding rock during the excavation process can be detected using on-site measuring devices, which is beneficial for realizing the dynamic design of the support structure. Pre-determining the thickness of the loosened zone in unsupported surrounding rock quickly and accurately is a prerequisite for realizing the dynamic design of the support structure and is also a major focus and challenge in the stability analysis of surrounding rock in tunnel engineering. The stability of the surrounding rock after tunnel excavation is directly related to the magnitude of in-situ stress, rock strength, and the degree of joint development. Extensive field measurements show that the range of the loosened zone in deep tunnels is directly related to the magnitude of in-situ stress and the strength of the surrounding rock; as the tunnel depth increases, the loosened zone increases approximately linearly in a certain direction. In particular, under high tectonic stress environments, the surrounding rock exhibits significant non-uniform failure characteristics, and the morphological characteristics of the loosened zone show a strong correlation with the in-situ stress field; the shape of the loosened zone is generally U-shaped or V-shaped.

[0004] Developing experimental equipment or improving experimental methods can simulate the failure process of tunnel surrounding rock under high stress in the laboratory; however, this method is limited by equipment and time consumption. Numerical methods can significantly reduce experimental costs and allow for repeatable tests, reducing errors caused by the discreteness of model test samples. However, currently, numerical methods have shortcomings in rapid calculation and analysis, making it difficult to meet the significant needs of dynamic design in deep-buried tunnel engineering. Analytical or semi-analytical / semi-numerical methods have the significant advantage of rapid parameter analysis, but existing methods struggle to consider the impact of high tectonic stress on the stability of the surrounding rock.

[0005] Therefore, developing design and analysis methods that simultaneously meet the requirements of engineering accuracy and rapid calculation is an issue that needs further research in tunnel engineering, especially for deep-buried tunnels in high tectonic stress zones along the Sichuan-Tibet Railway. Summary of the Invention

[0006] The purpose of this invention is to provide a rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones, characterized by the following steps:

[0007] S1: Calculate the stress distribution within the loosened zone of the surrounding rock of the deep-buried tunnel based on the engineering rock mass strength parameters;

[0008] S2: Calculate the distribution of external stress in the loosened zone of the surrounding rock of a deep-buried tunnel based on the geostress parameters of the engineering geological area given by geological survey data;

[0009] S3: A rapid calculation method for the range of loosened zone of surrounding rock in deep-buried tunnels considering the geostress characteristics of high tectonic stress zones is given;

[0010] S4: Construct a database of loosened zones in the surrounding rock of deep-buried tunnels under different geostress conditions, and provide a rapid evaluation formula for the maximum thickness of the loosened zone that reflects the influence of high tectonic stress.

[0011] Furthermore, S1 specifically includes the following steps:

[0012] S11: Under the theoretical framework of three-dimensional strength analysis of GZZ rock mass, the surrounding rock strength parameters include m b The calculation expressions for s and a are:

[0013]

[0014] In the formula m i Here, GSI represents the rock texture parameter, GSI represents the geological strength index, and D represents the excavation and blasting disturbance coefficient.

[0015] First, in-situ digital testing methods such as mobile phone photography are used to quickly acquire joint information of the surrounding rock at the tunnel face and upload it to the cloud in real time using 5G transmission technology. Then, the GSI value of the current tunnel face is remotely identified according to the calculation formula suggested by Hoek. Finally, the D value is taken according to Hoek's suggestion, and the m value is determined through on-site rebound dynamics tests or table lookup. i value.

[0016] S12: The GZZ three-dimensional strength theory of rock mass is used to describe the failure behavior of the surrounding rock within the loosened zone. The expression for the smooth GZZ criterion is:

[0017]

[0018] In the formula σ c Let I1 be the uniaxial compressive strength of intact rock, J2 be the first invariant of stress, and θ be the second invariant of stress deviatoricity.σ The Lode angle is the stress angle.

[0019] The plastic stress within the loosened ring is solved numerically. The equilibrium equations are in finite difference form:

[0020]

[0021] In the formula, r is the radial coordinate of the surrounding rock of the tunnel, σ r For the minimum principal stress, σ α The maximum principal stress is the out-of-plane stress σ within the loosened ring. z The intermediate principal stress is expressed as follows:

[0022]

[0023] The stress distribution of the loosened zone of the surrounding rock is calculated according to equations (2), (3), and (4).

[0024] Furthermore, the calculation steps for the stress distribution in the loosened zone of the surrounding rock in S12 are as follows:

[0025] S121: Based on the tunnel inner wall boundary conditions and equation (1), the maximum principal stress σ at the inner wall is solved using the fsolve function in Matlab software. α(1) ;

[0026] S122: Based on equations (2), (3), and (4), use the fsolve function in Matlab software to calculate r. (2) The stress component σ at the location r(2) , σ z(2) , σ α(2) ;

[0027] S123: Following this logic, use the fsolve function in Matlab to calculate r. (j) The stress component σ at the location r(j) , σ z(j) , σ α(j) The stress distribution within the loosened zone is obtained.

[0028] Furthermore, S2 specifically includes the following steps:

[0029] S21: The loosening zone range is described using a set of mapping functions, which can be represented by Taylor series:

[0030]

[0031] In the formula, c1, c -k All have m+1 unknown coefficients, and ζ is a complex variable.

[0032] S22: According to equation (5), two analytical functions are used to represent the stress distribution outside the loosened zone of the surrounding rock:

[0033]

[0034] The formula has 2n analytic function coefficients, and B1 and B2 are related to the self-weight stress σ. v and horizontal structural stress σ h The relevant expression is:

[0035]

[0036] The external stress components of the loosened zone of the surrounding rock can be expressed as:

[0037] σ x +σ y =4Re[Φ(ζ)] (10)

[0038]

[0039] In the formula

[0040] S23: Based on the stress boundary conditions on the loosened zone boundary of the surrounding rock, the equation for the analytical function is:

[0041]

[0042] In the formula X n and Y n The surface force components along the horizontal and self-weight directions can be calculated using the following formula:

[0043]

[0044] In the formula σ x and σ y These are the normal stress components along the x and y directions in a rectangular coordinate system, τ. xy is the shear stress component, and l and m are the direction cosines of the unit outward normal to the boundary point under discussion and the horizontal and self-weight directions, respectively.

[0045] Furthermore, the steps for solving the analytic function in S23 are as follows:

[0046] S231: Based on the stress distribution of the loosened zone determined in S12, calculate the surface force component X on the boundary of the elastic zone. n and Y n ;

[0047] S232: Expanding the line integral term on the right-hand side of equation (12) into a Fourier series is as follows:

[0048]

[0049] Let ζ in equation (14) take 2n+1 different boundary values, and use the Matlab software linear equation solver to directly determine the 2n+1 coefficients in equation (14);

[0050] S233: Expanding the fraction on the left-hand side of equation (12) with respect to the mapping function into a Fourier series is as follows:

[0051]

[0052] Let ζ in equation (15) take 2n+1 different boundary values, and use the Matlab software linear equation solver to directly determine the 2n+1 coefficients in equation (15);

[0053] S234: Substituting equations (14) and (15) into equation (12), we obtain the coefficients of the analytic function a by comparing the terms of the same power with respect to ζ. k and b k The linear equation system is solved directly using the linear equation solver in Matlab software. k and b k .

[0054] Furthermore, S3 specifically includes the following steps:

[0055] S31: Use the destructive proximity function FAI GZZ Quantitatively evaluate the degree of yielding or failure at a point in the principal stress space (FAI). GZZ This represents the distance from the stress state at any point to the hydrostatic stress axis. The distance from the ultimate stress state corresponding to this point to the hydrostatic stress axis The ratio, its expression is:

[0056]

[0057] Based on the stress contact conditions at the loosened zone boundary, the boundary equations for the loosened zone boundary are constructed as follows:

[0058]

[0059] In the formula, r1 and r2 are penalty factors.

[0060] S32: Using Equation (17) as the objective function and the coefficients of the mapping function in Equation (5) as the design variables, use an optimization algorithm to seek the optimal value of the objective function.

[0061] S33: After optimization using the particle swarm optimization algorithm, check whether the static equilibrium conditions on the loosened zone boundary meet the accuracy requirements according to equation (12). If yes, the calculation terminates and the optimal individual is output; if no, the number of particles and the number of iterations are appropriately increased and the calculation continues until the requirements are met.

[0062] S34: Substitute the optimal individual into equation (5) to output the range of the loosened zone of the surrounding rock.

[0063] Furthermore, S4 specifically includes the following steps:

[0064] S41: Calculate the loosening zone of the surrounding rock of deep-buried tunnels under different tectonic stress environments according to the procedures in S1-S3 and construct its database.

[0065] S42: The ratio of the average horizontal structural stress and self-weight stress to the uniaxial compressive strength of the rock, K. σ To assess the impact of ground stress level on tunnel surrounding rock stability, the expression is:

[0066]

[0067] Using the stress concentration factor K determined by the horizontal structure and the stress due to its own weight. SCF To assess the impact of ground stress differences on tunnel surrounding rock stability, the expression is:

[0068]

[0069] Based on the database constructed in S41, statistical analysis was performed on the maximum thickness r of the loosened zone. max With two dimensionless factors K σ and K SCF To establish a correspondence, an r max About K σ and K SCF The linear evaluation expression is obtained, and the slope coefficient and intercept coefficient in the linear expression are determined using the least squares method.

[0070] S43: Establish a segmented correction evaluation expression for the maximum thickness of the loosened zone of the surrounding rock during the dynamic excavation of the tunnel.

[0071] Furthermore, the process of establishing the piecewise correction evaluation expression in S43 is as follows:

[0072] S431: Utilize the surrounding rock information revealed at the tunnel face during tunnel excavation to establish a database of the maximum thickness of the loosened zone in the current tunnel as engineering geological conditions vary, based on the measured results of the loosened zone thickness.

[0073] S432: Using the surrounding rock information revealed at the tunnel face during tunnel excavation, the maximum thickness of the loosened zone is quickly evaluated based on the prediction formula obtained in S42;

[0074] S433: Using the surrounding rock information revealed at the tunnel face during tunnel excavation, the tunnel engineering geological conditions are dynamically segmented (graded). Based on the measured results in S431 and the predicted results in S432, a segmented correction evaluation expression for the maximum thickness of the loosened zone of the tunnel surrounding rock is established.

[0075] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0076] 1. The present invention proposes a rapid quantitative evaluation method for the stability of the surrounding rock of a deep-buried tunnel in a high tectonic stress zone. This method integrates an analytical solution for the elasticity of the outer domain of a complex-shaped loosening zone and a numerical solution for the plastic stress of the loosening zone of a circular tunnel, thereby achieving rapid evaluation of the stability of the surrounding rock.

[0077] 2. This invention utilizes two dimensionless factors to reflect the geostress environment of deeply buried tunnels, which can be used to quickly predict the maximum thickness of the loosened zone of the surrounding rock.

[0078] 3. The rock mass parameters required by the evaluation method described in this invention can all be quickly obtained on-site through digital measurement or field tests, enabling three-dimensional positive analysis of the surrounding rock stability in tunnel engineering. Attached Figure Description

[0079] Figure 1 The flowchart of a rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones provided by this invention is shown.

[0080] Figure 2 This is a schematic diagram of the numerical model for calculating the stress in the loosened zone of the S1 surrounding rock in a rapid quantitative evaluation method for the stability of the surrounding rock of a deep-buried tunnel in a high tectonic stress zone provided by the present invention.

[0081] Figure 3 This invention provides a rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones. The schematic diagram shows the analytical model for calculating the external stress of the loosened zone in step S2 of this invention.

[0082] Figure 4 The flowchart of the rapid calculation method for the range of the loosened zone of the surrounding rock in step S3 of the rapid quantitative evaluation method for the stability of the surrounding rock of a deep buried tunnel in a high tectonic stress zone provided by the present invention is shown. Detailed Implementation

[0083] The following will describe in more detail, with reference to the schematic diagram, a rapid quantitative evaluation method for the stability of surrounding rock in deep buried tunnels in high tectonic stress zones according to the present invention. The diagram illustrates preferred embodiments of the present invention. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the present invention.

[0084] like Figure 1 As shown, a rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones includes the following steps:

[0085] Step 1, refer to Figure 2 The stress distribution within the loosened zone of the surrounding rock of the deep-buried tunnel is calculated based on the rock mass strength parameters of the engineering project.

[0086] Step 1 specifically includes:

[0087] Step 11: Under the theoretical framework of three-dimensional strength analysis of GZZ rock mass, the surrounding rock strength parameters include m b The calculation expressions for s and a are:

[0088]

[0089] In the formula m i Here, GSI represents the rock texture parameter, GSI represents the geological strength index, and D represents the excavation and blasting disturbance coefficient.

[0090] First, in-situ digital testing methods such as mobile phone photography are used to quickly acquire joint information of the surrounding rock at the tunnel face and upload it to the cloud in real time using 5G transmission technology. Then, the GSI value of the current tunnel face is remotely identified according to the calculation formula suggested by Hoek. Finally, the D value is taken according to Hoek's suggestion, and the m value is determined through on-site rebound dynamics tests or table lookup. i value.

[0091] Step 12: The GZZ three-dimensional strength theory of rock mass is used to describe the failure behavior of the surrounding rock within the loosened zone. The expression for the smooth GZZ criterion is:

[0092]

[0093] In the formula, σ c Let I1 be the uniaxial compressive strength of intact rock, J2 be the first invariant of stress, and θ be the second invariant of stress deviatoricity. σ The Lode angle is the stress angle.

[0094] The plastic stress within the loosened ring is solved numerically. The equilibrium equations are in finite difference form:

[0095]

[0096] In the formula, r is the radial coordinate of the tunnel surrounding rock, σ r For the minimum principal stress, σ α The maximum principal stress is the out-of-plane stress σ within the loosened ring. z The intermediate principal stress is expressed as follows:

[0097]

[0098] The stress distribution of the loosened zone of the surrounding rock is calculated according to equations (2), (3), and (4).

[0099] The solution for the stress distribution in the loosened zone of the surrounding rock can be achieved by following these steps:

[0100] Step 121: Based on the tunnel inner wall boundary conditions and equation (2), use the fsolve function in Matlab software to solve for the maximum principal stress σ at the inner wall. α(1) ;

[0101] Step 122: Based on equations (2), (3), and (4), use the fsolve function in Matlab software to calculate r. (2) The stress component σ at the location r(2) , σ z(2) , σ α(2) ;

[0102] Steps 1, 2, and 3: Following this pattern, use the `fsolve` function in Matlab to calculate `r`. (j) The stress component σ at the location r(j) , σ z(j) , σ α(j) The stress distribution within the loosened zone is obtained.

[0103] Step 2, refer to Figure 3 Based on the geostress parameters of the engineering geological area given by geological exploration data, the distribution of external stress in the loosened zone of the surrounding rock of the deep-buried tunnel is calculated.

[0104] Step 2 specifically includes:

[0105] Step 21: Use a set of mapping functions to describe the loosening zone range, which can be represented by Taylor series as follows:

[0106]

[0107] In the formula, c1, c -k Both have m+1 unknown coefficients, and ζ is a complex variable.

[0108] Step 22: According to equation (5), two analytical functions are used to represent the stress distribution outside the loosened zone of the surrounding rock:

[0109]

[0110] In the formula, there are 2n analytic function coefficients, and B1 and B2 are related to the self-weight stress σ. v and horizontal structural stress σ h The relevant expression is:

[0111]

[0112] The external stress components of the loosened zone of the surrounding rock can be expressed as:

[0113] σ x +σ y =4Re[Φ(ζ)] (10)

[0114]

[0115] In the formula,

[0116] Step 23, based on the stress boundary conditions on the loosened zone boundary of the surrounding rock, solve for the equation of the analytical function as follows:

[0117]

[0118] In the formula, X n and Y n The surface force components along the horizontal and self-weight directions can be calculated using the following formula:

[0119]

[0120] In the formula, σ x and σ y These are the normal stress components along the x and y directions in a rectangular coordinate system, τ. xy is the shear stress component, and l and m are the direction cosines of the unit outward normal to the boundary point under discussion and the horizontal and self-weight directions, respectively.

[0121] The solution to the analytic function is achieved through the following steps:

[0122] Step 231: Based on the stress distribution of the loosened zone determined in Step 12, calculate the surface force component X on the boundary of the elastic zone. n and Y n ;

[0123] Step 232: Expand the line integral term on the right-hand side of equation (12) into a Fourier series as follows:

[0124]

[0125] Let ζ in equation (12) take 2n+1 different boundary values, and use the Matlab software linear equation solver to directly determine the 2n+1 coefficients in equation (14);

[0126] Step 233: Expand the fraction on the left-hand side of equation (12) with respect to the mapping function into a Fourier series as follows:

[0127]

[0128] Let ζ in equation (12) take 2n+1 different boundary values, and use the Matlab software linear equation solver to directly determine the 2n+1 coefficients in equation (15);

[0129] Step 234: Substitute equations (14) and (15) into equation (12), and obtain the coefficients a of the analytic function by comparing the terms of the same power with respect to ζ. k and b k The linear equation system is solved directly using the linear equation solver in Matlab software. k and b k .

[0130] Step 3, refer to Figure 4 A rapid calculation method for the loosening zone of surrounding rock in deep-buried tunnels, considering the geostress characteristics of high tectonic stress zones, is presented.

[0131] Step 3 specifically includes:

[0132] Step 31: Use the failure proximity function FAIGZZ to quantitatively evaluate the degree of yielding or failure at a point. In the principal stress space, FAIGZZ represents the distance from the stress state at any point to the hydrostatic stress axis. The distance from the ultimate stress state corresponding to this point to the hydrostatic stress axis The ratio, its expression is:

[0133]

[0134] Based on the stress contact conditions at the loosened zone boundary, the boundary equations for the loosened zone boundary are constructed as follows:

[0135]

[0136] In the formula, r1 and r2 are penalty factors.

[0137] In this embodiment, all values ​​are taken as 100, R0 is the tunnel radius, the boundary condition for soft rock tunnels is to make the value of F(X) 0, and the boundary condition for hard rock tunnels is to make the value of F(X) as close to 0 as possible.

[0138] Step 32: Using Equation (17) as the objective function and the mapping function coefficients in Equation (5) as design variables, use an optimization algorithm to find the optimal value of the objective function.

[0139] This embodiment uses a particle swarm optimization algorithm toolbox written in Matlab, setting the range of design variable c1 to [0, 5R0], and the rest c -k All values ​​are [-R0, R0], the number of particles is 20, the inertial constant is 0.6, the acceleration constant is 1, the maximum flight speed is 10% of the maximum speed, and the maximum number of iterations is 400.

[0140] Step 33: After optimization using the particle swarm optimization algorithm, check whether the static equilibrium conditions on the loosened zone boundary meet the accuracy requirements according to equation (12). If yes, the calculation terminates and the optimal individual is output; if not, the number of particles and the number of iterations are appropriately increased to continue the calculation until the requirements are met.

[0141] Step 34: Substitute the optimal individual into equation (5) to output the range of the loosened zone of the surrounding rock.

[0142] Step 4: Construct a database of loosened zones in the surrounding rock of deep-buried tunnels under different geostress conditions, and provide a rapid evaluation formula for the maximum thickness of the loosened zone that reflects the influence of high tectonic stress.

[0143] Step 4 specifically includes:

[0144] Step 41: Calculate the loosening zone of the surrounding rock of deep-buried tunnels under different tectonic stress environments and construct its database according to the process in Steps 1 to 3.

[0145] Step 42: Use the ratio K of the average horizontal structural stress and self-weight stress to the uniaxial compressive strength of the rock. σ To assess the impact of ground stress level on tunnel surrounding rock stability, the expression is:

[0146]

[0147] Using the stress concentration factor K determined by the horizontal structure and the stress due to its own weight. SCF To assess the impact of ground stress differences on tunnel surrounding rock stability, the expression is:

[0148]

[0149] Based on the database constructed in step 41, statistical analysis was performed on the maximum thickness r of the loosened zone. max With two dimensionless factors K σ and K SCF To establish a correspondence, an r max About K σ and K SCF The linear evaluation expression is obtained, and the slope coefficient and intercept coefficient in the linear expression are determined using the least squares method.

[0150] Step 43: Establish a segmented correction evaluation expression for the maximum thickness of the loosened zone of the surrounding rock during the dynamic excavation of the tunnel.

[0151] Step 43 can be implemented according to the following steps, including:

[0152] Step 431: Using the surrounding rock information revealed at the tunnel face during tunnel excavation, establish a database of the maximum thickness of the loosened zone in the current tunnel as engineering geological conditions vary, based on the measured results of the loosened zone thickness.

[0153] Step 432: Using the surrounding rock information revealed at the tunnel face during tunnel excavation, quickly evaluate the maximum thickness of the loosened zone based on the prediction formula obtained in Step 42;

[0154] Step 433: Using the surrounding rock information revealed at the tunnel face during tunnel excavation, the engineering geological conditions of the tunnel are dynamically segmented (graded). Based on the measured results in Step 431 and the predicted results in Step 432, a segmented correction evaluation expression for the maximum thickness of the loosened zone of the tunnel surrounding rock is established, and a rapid quantitative evaluation of the stability of the surrounding rock of a deep-buried tunnel in a high tectonic stress zone is completed.

[0155] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones, characterized in that, Includes the following steps: S1: Calculate the stress distribution within the loosened zone of the surrounding rock of a deep-buried tunnel based on the engineering rock mass strength parameters; S2: Calculate the distribution of external stress in the loosened zone of the surrounding rock of a deep-buried tunnel based on the geostress parameters of the engineering geological area given by geological survey data; S3: A rapid calculation method for the range of loosened zone of surrounding rock in deep-buried tunnels considering the geostress characteristics of high tectonic stress zones is given; S4: Construct a database of loosened zones in the surrounding rock of deep-buried tunnels under different geostress conditions, and provide a rapid evaluation formula for the maximum thickness of the loosened zone that reflects the influence of high tectonic stress. S3 specifically includes: S31: The FAIGZZ failure proximity function is used to quantitatively evaluate the degree of yielding or failure at a point. In the principal stress space, FAIGZZ represents the distance from the stress state at any point to the hydrostatic stress axis. The distance from the ultimate stress state corresponding to this point to the hydrostatic stress axis The ratio, expressed by Formula Sixteen, is as follows: ； Based on the stress contact conditions at the loosened zone boundary, the boundary equation for the loosened zone boundary is expressed by Equation 17: ； In the formula, and As a penalty factor; Step 32: Using Formula 17 as the objective function and the mapping function coefficients of Formula 5 as design variables, use an optimization algorithm to find the optimal value of the objective function. Formula 5 is expressed as: ； in, , All are m +1 unknown coefficient, It is a complex variable; Step 33: After optimization using the particle swarm optimization algorithm, check whether the static equilibrium conditions on the loosened zone boundary meet the accuracy requirements according to Formula 12. If yes, the calculation terminates and the optimal individual is output; if not, the number of particles and the number of iterations are appropriately increased to continue the calculation until the requirements are met. Formula 12 is expressed as: ； in, and These are the surface force components along the horizontal and self-weight directions; S34: Substitute the optimal individual into Formula 5 to output the range of the loosened zone of the surrounding rock; S4 specifically includes: S41: Calculate the loosened zone of the surrounding rock of deep-buried tunnels under different tectonic stress environments according to the procedures in S1 to S3 and construct its database; S42: The ratio of the average stress of horizontal structures and their own weight to the uniaxial compressive strength of the rock. To assess the impact of ground stress level on tunnel surrounding rock stability, the expression is: ； Using the stress concentration factor determined by horizontal structural features and self-weight stress. To assess the impact of ground stress differences on tunnel surrounding rock stability, the expression is: ； Based on the database constructed in S41, the maximum thickness of the loosened zone was statistically analyzed. With two dimensionless factors and To establish a correspondence. about and The linear evaluation expression is derived, and the slope coefficient and intercept coefficient in the linear expression are determined using the least squares method. S43: Establish a segmented correction evaluation expression for the maximum thickness of the loosened zone of surrounding rock during dynamic tunnel excavation; S43 is implemented according to the following steps, including: S431: Utilize the surrounding rock information revealed at the tunnel face during tunnel excavation to establish a database of the maximum thickness of the loosened zone in the current tunnel as engineering geological conditions vary, based on the measured results of the loosened zone thickness. S432: Using the surrounding rock information revealed at the tunnel face during tunnel excavation, the maximum thickness of the loosened zone is quickly evaluated based on the prediction formula obtained in S42; S433: Utilizing the surrounding rock information revealed at the tunnel face during tunnel excavation, the engineering geological conditions of the tunnel are dynamically segmented. Based on the measured results in S431 and the predicted results in S432, a segmented correction evaluation expression for the maximum thickness of the loosened zone of the tunnel surrounding rock is established, thus completing a rapid quantitative evaluation of the stability of the surrounding rock of a deep-buried tunnel in a high tectonic stress zone.

2. The rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones according to claim 1, characterized in that, S1 specifically includes the following steps: S11: Under the theoretical framework of three-dimensional strength analysis of GZZ rock mass, the required surrounding rock strength parameters include... , and ; S12: The GZZ three-dimensional strength theory of rock mass is used to describe the failure behavior of the surrounding rock within the loosened zone. The expression for the smooth GZZ criterion is: ； In the GZZ criterion The uniaxial compressive strength of intact rock. As the first invariant of stress, It is the second invariant of stress deviator; The stress distribution in the loosened zone of the surrounding rock is calculated by combining the GZZ criterion, the relationship between the out-of-plane and in-plane stress components of the loosened zone, and the equilibrium equation in the form of a difference equation.

3. The rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones according to claim 2, characterized in that, The method for determining the surrounding rock strength parameters is as follows: First, in-situ digital testing methods such as mobile phone photography are used to quickly acquire the joint information of the surrounding rock at the working face and upload it to the cloud in real time using 5G transmission technology. Then, the current working face strength is remotely identified according to the calculation formula suggested by Hoek. GSI The value was ultimately determined according to Hoek's suggestion. D The value is determined through on-site rebound dynamics testing or by looking up a table. m i value.

4. The rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones according to claim 3, characterized in that, In step S12, the solution for the stress distribution in the loosened zone of the surrounding rock includes the following steps: S121: Based on the tunnel inner wall boundary conditions and the GZZ strength criterion, the maximum principal stress at the inner wall is solved using the fsolve function in Matlab software. ; S122: Based on the GZZ strength criterion, the relationship between the out-of-plane and in-plane stress components of the loosened zone of the surrounding rock, and the difference-form equilibrium equation, the calculation was performed using the fsolve function in Matlab software. r (2) Stress components at the point , , ; S123: Use the fsolve function in Matlab software to calculate... Stress components at the point , , The stress distribution within the loosened zone is obtained.

5. The rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones according to claim 4, characterized in that, S2 specifically includes the following steps: S21: Use a set of mapping functions to describe the loosening zone range, and use Taylor series representation for the mapping functions; S22: Based on the mapping function represented by Taylor series, two analytical functions are used to represent the stress distribution outside the loosened zone of the surrounding rock; S23: Solve for the analytical function based on the stress boundary conditions on the loosened zone boundary of the surrounding rock.

6. The rapid quantitative evaluation method for the stability of surrounding rock in deep-buried tunnels in high tectonic stress zones according to claim 5, characterized in that, In step S23, solving the analytic function includes the following steps: S231: Based on the stress distribution of the loosened zone determined in S12, calculate the surface force components on the boundary of the elastic zone. X n and Y n ; S232: Surface force components X n and Y n The integral term expands into a Fourier series; Let the independent variable in the series be 2. n With +1 different boundary values, the 2nd step in the series is directly determined using the linear equation solver in Matlab software. n +1 coefficient; S233: Expand the fraction with respect to the mapping function in S21 into a Fourier series; Let the independent variable in the series be 2. n With +1 different boundary values, the 2nd step in the series is directly determined using the linear equation solver in Matlab software. n +1 coefficient; S234: Substitute the two Fourier series into the stress boundary conditions, obtain a system of linear equations about the coefficients of the analytic function by comparing the terms of the same power with respect to the independent variable, and directly determine the analytic function using the linear equation solver in Matlab software.

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