Surrounding rock strength calculation method and system based on equivalent support reaction of prestressed anchor rod

Abstract

The application discloses a surrounding rock strength calculation method and system based on prestressed anchor equivalent supporting reaction, relates to the technical field of surrounding rock data processing, and comprises the following steps: obtaining initial mechanical parameters of surrounding rock, tunnel excavation parameters and design parameters of anchor supporting; based on the design parameters, calculating the cohesion increment, the elastic modulus of the anchor surrounding rock composite structure and the equivalent supporting reaction respectively; superimposing the cohesion increment and the initial cohesion of the surrounding rock to obtain the total cohesion; applying the equivalent supporting reaction as a boundary condition to a bearing arch model; parallelly calculating the rock mass strength safety factor, the anchoring system efficiency coefficient and the comprehensive deformation stability coefficient; and synthesizing the rock mass strength safety factor, the anchoring system efficiency coefficient and the comprehensive deformation stability coefficient to obtain the final surrounding rock strength safety factor. Through quantitative analysis, the application reduces the possibility of engineering risk and provides technical support for this special and complex engineering type of large-span tunnels.

Description

Technical Field

[0001] This invention relates to the field of surrounding rock data processing technology, specifically to a method and system for calculating surrounding rock strength based on the equivalent support reaction force of prestressed anchor bolts. Background Technology

[0002] In underground engineering, after tunnel excavation, the redistribution of stress in the surrounding rock will form a self-supporting pressure arch within a certain range above the tunnel roof, thereby reducing the load on the directly supported structure. The classic "Protodyakonov arch" theory is based on this assumption. For conventional span tunnels, the rock-bearing arch formed below the pressure arch in combination with shotcrete and anchor support has become a mature design concept.

[0003] However, for rock tunnels with spans exceeding 30 meters, especially those reaching 70 meters and characterized by ultra-flat (extremely low rise-to-span ratio), the support design faces unprecedented theoretical challenges and engineering dilemmas: the classical pressure arch theory fails, and the failure modes become more complex. The large span and extremely low rise-to-span ratio significantly weaken the stress arch effect of the surrounding rock at the tunnel crown, expand the arch foot effect area, and make it difficult for natural pressure arches to form stably or reach extremely high heights. This leads to a dramatic increase in the range and thickness of loosened surrounding rock beneath the pressure arch, transforming the potential failure mode from a single arch collapse to a complex coupled mode involving roof bending settlement, sidewall shear slip, and even overall structural instability. The applicability of classical theories under such extreme conditions is seriously questionable.

[0004] Meanwhile, traditional support design concepts and quantitative methods are insufficient. Current engineering analyses of load-bearing arches often simplify them to three-hinged arches or assume they bear all initial ground stress. This contradicts the actual stress state of arch structures in mega-span tunnels, where anchor-sprayed support provides overall reinforcement and stress control to a large area of ​​low-stress rock mass, forming an arch structure that primarily bears secondary loosening loads. This leads to analysis results that are either overly conservative and uneconomical, or pose safety hazards. Existing design methods lack precise quantification of the core role of system anchors. They fail to couple the enhancing effect of fully bonded anchors on the strength and stiffness of the surrounding rock with the active support reaction force provided by prestressed anchors within a unified theoretical framework and scientifically incorporate it into the stability criteria of the load-bearing arch. Anchor support design still largely relies on engineering analogies and experience.

[0005] Therefore, developing a set of theories and methods for calculating the strength of surrounding rock that are applicable to giant-span flat tunnels, can accurately quantify the dual effects of anchor bolt support, and adopt a bearing arch model that is more in line with the actual stress state has become a key technical challenge in solving the core contradiction of how to design such projects to be both safe and economical. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a method and system for calculating the strength of surrounding rock based on the equivalent support reaction force of prestressed anchor bolts.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The method for calculating the surrounding rock strength based on the equivalent support reaction of prestressed anchor bolts includes the following steps:

[0009] Step S1: Obtain the initial mechanical parameters of the surrounding rock, tunnel excavation parameters, and design parameters of the anchor bolt support;

[0010] Step S2: Based on the design parameters, calculate the cohesion increment provided by the anchor system, the initial elastic modulus and the deteriorated elastic modulus of the anchor-surrounding rock composite structure, and the equivalent support reaction force of the prestressed anchor or anchor cable.

[0011] Step S3: The calculated cohesion increment is superimposed with the initial cohesion of the surrounding rock to obtain the total cohesion of the reinforced surrounding rock; the equivalent support reaction force is applied as a boundary condition to the bearing arch model.

[0012] Step S4: Parallel calculation of rock mass strength safety factor, anchoring system effectiveness coefficient, and comprehensive deformation stability coefficient;

[0013] Step S5: Dynamically synthesize the rock mass strength safety factor, anchoring system efficiency coefficient, and comprehensive deformation stability coefficient through a comprehensive quantitative model to obtain the final surrounding rock strength safety factor, and conduct stability assessment and decision-making based on it.

[0014] Furthermore, in step S2, the calculation of the cohesion increment specifically includes: determining it based on the shear strength, diameter, and circumferential and longitudinal spacing of the anchor bolt in the surrounding rock.

[0015] Further, in step S2, the calculation of the initial elastic modulus and the deteriorated elastic modulus of the anchor bolt and surrounding rock composite structure specifically includes: treating the anchor bolt and surrounding rock as composite materials, and calculating the initial elastic modulus and the deteriorated elastic modulus of the composite structure based on the initial and deteriorated elastic modulus of the surrounding rock, the elastic modulus and cross-sectional area of ​​the anchor bolt material, and the anchor bolt spacing, and setting the anchor bolt to not affect the Poisson's ratio of the surrounding rock in the calculation.

[0016] Furthermore, in step S2, the calculation of the equivalent support reaction force specifically includes: converting the prestress applied by a single prestressed anchor rod or anchor cable into an equivalent uniformly distributed pressure acting on the support boundary based on its circumferential and longitudinal spacing.

[0017] Further, in step S4, the calculation of the rock mass strength safety factor specifically includes: comparing the total cohesion of the reinforced surrounding rock, the shear strength determined by the shear surface normal stress and internal friction angle considering the contribution of the equivalent support reaction force, with the average shear stress; wherein, the average shear stress is calculated by the modified pressure arch theory, and the load reduction effect of the equivalent support reaction force on the pressure arch is taken into account.

[0018] Furthermore, in step S4, the calculation of the anchoring system efficiency coefficient specifically includes: comparing the shear resistance provided per unit area of ​​the anchor system with the rock mass shear requirements, and verifying the cooperative working ability of the anchor and the surrounding rock within the elastic deformation range, and taking the smaller value of the two results as the coefficient.

[0019] Furthermore, in step S4, the calculation of the comprehensive deformation stability coefficient specifically includes: evaluating the deformation stability of the system from the perspective of energy balance by comparing the total work of the support system, which consists of the work done by the equivalent support reaction force and the increase in elastic energy storage of the composite, with the maximum elastic deformation energy of the bearing arch itself.

[0020] A system for calculating the strength of surrounding rock based on the equivalent support reaction of prestressed anchor bolts is provided to implement any of the methods for calculating the strength of surrounding rock based on the equivalent support reaction of prestressed anchor bolts, including:

[0021] The parameter input and management module is used to receive and store the initial mechanical parameters of the surrounding rock, the geometric and excavation parameters of the tunnel, and the design parameters of the anchor bolt support input by the user.

[0022] A multi-dimensional effect calculation engine is connected to the parameter input and management module, used to call stored parameters and perform core calculations;

[0023] The comprehensive safety assessment and output module is connected to the multi-dimensional effect calculation engine. It receives the safety factor, synthesizes it into the final surrounding rock strength safety factor through the built-in comprehensive quantification model, and outputs the stability level assessment result and visualization report.

[0024] Furthermore, the multi-dimensional effect calculation engine includes:

[0025] The load-bearing arch modeling submodule is used to automatically define the loosened zone and construct a hingeless arch calculation model of the rock load-bearing arch by calling numerical simulation results through an external interface based on the input excavation parameters, and generating its geometric properties and load information.

[0026] The parameter enhancement calculation submodule is used to synchronously execute and output the calculation of cohesion increment, initial and deteriorated elastic modulus of the anchor bolt surrounding rock composite structure, and equivalent support reaction force based on the input anchor bolt support design parameters.

[0027] The safety factor analysis submodule is connected to the parameter enhancement calculation submodule and the bearing arch modeling submodule, and is used to calculate the rock mass strength safety factor, anchoring system effectiveness coefficient and comprehensive deformation stability coefficient in parallel.

[0028] Furthermore, the system also includes a support scheme optimization suggestion module, which is connected to the comprehensive safety assessment and output module. This module is used to analyze the final surrounding rock strength safety factor. If the final surrounding rock strength safety factor does not meet the requirements, optimization suggestions are automatically generated based on a preset rule base.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. This invention represents a fundamental breakthrough in support design for mega-span flat tunnels, moving from empirical qualitative to theoretical quantitative approaches. By establishing a precise mathematical relationship between anchor bolt parameters and the macroscopic mechanical properties of the surrounding rock, this invention quantifies the support effects of full-length bonded anchor bolts and prestressed anchor bolts into key design parameters such as cohesion increment, composite modulus, and equivalent support reaction force. This provides a calculable and optimizable scientific design basis for mega-span tunnels, overcoming the blindness and uncertainty of empirical methods.

[0031] 2. This invention establishes a multi-dimensional and diagnosable safety assessment system adapted to the complex failure modes of mega-span tunnels. Addressing the multi-mode coupled failures that may occur in mega-span tunnels, such as roof bending and shear slippage, it abandons the fuzzy evaluation of a single safety factor and innovatively calculates the safety factors of three independent dimensions—rock mass strength, anchoring system effectiveness, and deformation stability—in parallel. Through dynamic weighting and compounding, the final safety factor not only reflects the overall stability level, but its formation process can also accurately pinpoint the specific sources of risk. This achieves an improvement from overall fuzzy judgment to clear diagnosis of shortcomings, enhancing the pertinence and reliability of risk control.

[0032] 3. Under the premise of ensuring safety, this invention provides significant economic optimization potential for the extremely expensive mega-span tunnel project. By accurately quantifying the support contribution and adopting a more realistic hingeless arch-elastic foundation beam model, the design load and support capacity can be scientifically matched. This allows for ensuring safety reserves while avoiding unnecessary material surplus, and guides designers to optimize parameters such as anchor spacing and prestress. This has important practical economic significance for controlling the overall cost of this special type of project, mega-span tunnel. Attached Figure Description

[0033] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0034] Figure 1 This is a flowchart illustrating an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the system structure according to an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1 As shown, the method for calculating the surrounding rock strength based on the equivalent support reaction force of prestressed anchor bolts includes the following steps:

[0038] Step S1: Obtain the initial mechanical parameters of the surrounding rock, tunnel excavation parameters, and design parameters of the anchor bolt support;

[0039] Step S2: Based on the design parameters, calculate the cohesion increment provided by the anchor system, the initial elastic modulus and the deteriorated elastic modulus of the anchor-surrounding rock composite structure, and the equivalent support reaction force of the prestressed anchor or anchor cable.

[0040] Step S3: The calculated cohesion increment is superimposed with the initial cohesion of the surrounding rock to obtain the total cohesion of the reinforced surrounding rock; the equivalent support reaction force is applied as a boundary condition to the bearing arch model.

[0041] The bearing arch model refers to the structure formed by the system anchor rods reinforcing the loose surrounding rock at the arch top, which is simplified into a hingeless arch with the arch foot and sidewall elastically fixed, and a calculation and analysis system that works in synergy with the sidewall elastic foundation beam model to bear the load.

[0042] Step S4: Parallel calculation of rock mass strength safety factor, anchoring system effectiveness coefficient, and comprehensive deformation stability coefficient;

[0043] Step S5: Dynamically synthesize the rock mass strength safety factor, anchoring system efficiency coefficient, and comprehensive deformation stability coefficient through a comprehensive quantitative model to obtain the final surrounding rock strength safety factor, and conduct stability assessment and decision-making based on it.

[0044] In step S2, the calculation of the cohesion increment specifically includes: determining it based on the shear strength, diameter, and circumferential and longitudinal spacing of the anchor bolt in the surrounding rock.

[0045] Since full-length anchored mortar bolts do not apply prestress, they belong to a passive support system. Their function is only to improve the overall integrity of the fractured surrounding rock. Therefore, the strength of the surrounding rock after anchor reinforcement will be improved to a certain extent. The cohesion of the surrounding rock after reinforcement with full-length mortar bolts can be calculated using the following formula:

[0046] ,in, ,

[0047] in, This indicates the increment in cohesion provided by the anchor system; Indicates the initial cohesion of the surrounding rock; Indicates the shear strength of the anchor bolt; This represents the cross-sectional area of ​​the anchor bolt; Indicates the circumferential spacing of the anchor bolts; Indicates the longitudinal spacing of the anchor bolts; Indicates the diameter of the anchor bolt.

[0048] In step S2, the calculation of the initial elastic modulus and the deteriorated elastic modulus of the anchor bolt and surrounding rock composite structure specifically includes: treating the anchor bolt and surrounding rock as composite materials, and calculating the initial elastic modulus and the deteriorated elastic modulus of the composite structure based on the initial and deteriorated elastic modulus of the surrounding rock, the elastic modulus and cross-sectional area of ​​the anchor bolt material, and the anchor bolt spacing, respectively, and setting the anchor bolt to not affect the Poisson's ratio of the surrounding rock in the calculation.

[0049] The reinforcement effect of fully anchored mortar anchors on surrounding rock not only increases its strength but also improves its deformation characteristics. Overall, anchors have a relatively small impact on the deformation parameters of surrounding rock under hard rock conditions, and the deformation of surrounding rock in hard rock tunnels is mainly elastic rebound. Since deformation parameters have almost no impact on the assessment of surrounding rock stability, it can be assumed that the reinforced surrounding rock remains an isotropic material, and that the anchor does not affect the Poisson's ratio. The elastic modulus before and after yielding of the anchor-surround rock composite structure can be calculated using the following formula:

[0050]

[0051]

[0052] in, and These represent the initial elastic modulus and the deteriorated elastic modulus of the anchor bolt surrounding rock composite structure, respectively. and The initial elastic modulus and the deteriorated elastic modulus of the surrounding rock are described respectively; This indicates the elastic modulus of the anchor bolt material.

[0053] In step S2, the calculation of the equivalent support reaction force specifically includes: converting the prestress applied by a single prestressed anchor rod or anchor cable into a uniformly distributed pressure acting on the support boundary based on its circumferential and longitudinal spacing.

[0054] The prestress provided by prestressed anchor bolts or prestressed anchor cables can be converted into an equivalent support reaction force acting on the tunnel wall. The following methods can be used for calculation:

[0055]

[0056] in, This indicates the prestress applied to the anchor bolt.

[0057] In step S4, the calculation of the rock mass strength safety factor specifically includes: comparing the total cohesion of the reinforced surrounding rock, the shear strength determined by the shear surface normal stress considering the contribution of the equivalent support reaction force, and the internal friction angle with the average shear stress; wherein, the average shear stress is calculated by the modified pressure arch theory, and the load reduction effect of the equivalent support reaction force on the pressure arch is taken into account, and the specific formula is:

[0058]

[0059] in, Indicates the safety factor for rock mass strength. This indicates the total cohesion of the surrounding rock after reinforcement. This represents the average normal stress on the shear plane. Indicates the internal friction angle of the surrounding rock. This represents the average shear stress acting on the shear plane;

[0060] The formulas for calculating the average normal stress and the average shear stress are as follows:

[0061] ,

[0062] in, Indicates the weight of the rock mass. Indicates the depth of the plastic zone. Indicates the half span of the pressure arch. Indicates the lateral pressure coefficient. The depth of the tunnel is indicated by the plastic zone depth and the half-span of the pressure arch. This is obtained through elastoplastic numerical simulation, such as by calculating the distribution of the plastic zone of the surrounding rock after tunnel excavation using the finite element method. The lateral pressure coefficient is selected empirically based on the type of surrounding rock. For example, for general rock masses, the K value is between 0.5 and 1.5.

[0063] In step S4, the calculation of the anchoring system effectiveness coefficient specifically includes: comparing the shear resistance provided per unit area of ​​the anchor system with the rock mass shear requirements, and verifying the cooperative working ability of the anchor and the surrounding rock within the elastic deformation range, taking the smaller value of the two results as the coefficient. The specific formula is as follows:

[0064]

[0065] in, Indicates the efficiency coefficient of the anchoring system. This represents the sub-coefficient of shear capacity of the anchor bolt. This represents the anchor bolt-surrounding rock cooperative deformation coefficient. This indicates the allowable tensile strain of the anchor bolt material, which is determined based on the yield strength of the anchor bolt material.

[0066] In step S4, the calculation of the comprehensive deformation stability coefficient specifically includes: by comparing the total work of the support system, consisting of the work done by the equivalent support reaction force and the increase in elastic energy storage of the composite, with the maximum elastic deformation energy of the bearing arch itself, the deformation stability of the system is evaluated from the perspective of energy balance. The specific formula is as follows:

[0067]

[0068] in, This represents the overall deformation stability coefficient. This represents the maximum calculated displacement of the crown of the load-bearing arch. The characteristic compressive strain of the composite is represented by the average compressive strain of the bearing arch section under axial force. This indicates the volume of the rock-supported arch. This indicates the maximum calculated stress at the most unfavorable section of the load-bearing arch, which may be the maximum compressive or tensile stress. Indicates corresponding to The strain, through It is obtained by dividing by the initial elastic modulus of the anchor bolt surrounding rock composite structure.

[0069] The final surrounding rock strength safety factor is obtained by combining the rock mass strength safety factor, the anchoring system effectiveness coefficient, and the comprehensive deformation stability coefficient. The specific formula is as follows:

[0070]

[0071] in, This represents the final safety factor for the surrounding rock strength. The synergy-bottom adjustment factor is defined by the following logic:

[0072] 1. Find the minimum value among the rock mass strength safety factor, anchoring system efficiency coefficient, and comprehensive deformation stability coefficient, and calculate the arithmetic mean of these three values;

[0073] 2. Next, compare the minimum value with 85% of the arithmetic mean, and determine the value of the synergy-bottom-plate adjustment factor based on the comparison result:

[0074] If the minimum value is greater than or equal to 85% of the arithmetic mean, the system is considered to be in a relatively balanced state. In this case, the adjustment factor should be set to a larger value, such as around 0.7, so that the final safety factor composite result reflects more the weighted average level of the three component coefficients, that is, it trusts more the synergistic effect between the various parts of the system.

[0075] If the minimum value is less than 85% of the average value, it is determined that there is a weak link in the system that is significantly lower than other parts. In this case, the adjustment factor should be set to a small value, such as around 0.3, so that the final safety factor is more strongly affected by the minimum value, thereby more sensitively reflecting the suppression effect of the weakness in the overall assessment.

[0076] like Figure 2 As shown, a rock mass strength calculation system based on the equivalent support reaction of prestressed anchor bolts is used to implement any of the rock mass strength calculation methods based on the equivalent support reaction of prestressed anchor bolts, including:

[0077] The parameter input and management module is used to receive and store the initial mechanical parameters of the surrounding rock, the geometric and excavation parameters of the tunnel, and the design parameters of the anchor bolt support input by the user.

[0078] A multi-dimensional effect calculation engine is connected to the parameter input and management module, used to call stored parameters and perform core calculations;

[0079] The comprehensive safety assessment and output module is connected to the multi-dimensional effect calculation engine. It receives the safety factor, synthesizes it into the final surrounding rock strength safety factor through the built-in comprehensive quantification model, and outputs the stability level assessment result and visualization report.

[0080] The multi-dimensional effect calculation engine includes:

[0081] The load-bearing arch modeling submodule is used to automatically define the loosened zone and construct a hingeless arch calculation model of the rock load-bearing arch by calling numerical simulation results through an external interface based on the input excavation parameters, and generating its geometric properties and load information.

[0082] The parameter enhancement calculation submodule is used to synchronously execute and output the calculation of cohesion increment, initial and deteriorated elastic modulus of the anchor bolt surrounding rock composite structure, and equivalent support reaction force based on the input anchor bolt support design parameters.

[0083] The safety factor analysis submodule is connected to the parameter enhancement calculation submodule and the bearing arch modeling submodule, and is used to calculate the rock mass strength safety factor, anchoring system effectiveness coefficient and comprehensive deformation stability coefficient in parallel.

[0084] The system also includes a support scheme optimization suggestion module, which is connected to the comprehensive safety assessment and output module. This module is used to analyze the final surrounding rock strength safety factor. If the final surrounding rock strength safety factor does not meet the requirements, optimization suggestions are automatically generated based on a preset rule base.

[0085] Any combination of one or more computer-readable media may be used. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example, but not limited to, a system, apparatus, or device representing electrical, magnetic, optical, electromagnetic, infrared, or semiconductor technologies, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device.

[0086] The examples described herein are merely preferred embodiments of the invention and are not intended to limit the concept and scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the design concept of the invention should fall within the protection scope of the invention.

Claims

1. A method for calculating the strength of surrounding rock based on the equivalent support reaction force of prestressed anchor bolts, characterized in that, Includes the following steps: Step S1: Obtain the initial mechanical parameters of the surrounding rock, tunnel excavation parameters, and design parameters of the anchor bolt support; Step S2: Based on the design parameters, calculate the cohesion increment provided by the anchor system, the initial elastic modulus and the deteriorated elastic modulus of the anchor-surrounding rock composite structure, and the equivalent support reaction force of the prestressed anchor or anchor cable. Step S3: The calculated cohesion increment is superimposed with the initial cohesion of the surrounding rock to obtain the total cohesion of the reinforced surrounding rock; the equivalent support reaction force is applied as a boundary condition to the bearing arch model. Step S4: Parallel calculation of rock mass strength safety factor, anchoring system effectiveness coefficient, and comprehensive deformation stability coefficient; Step S5: Dynamically synthesize the rock mass strength safety factor, anchoring system efficiency coefficient, and comprehensive deformation stability coefficient through a comprehensive quantitative model to obtain the final surrounding rock strength safety factor, and conduct stability assessment and decision-making based on it.

2. The method according to claim 1, characterized in that, In step S2, the calculation of the cohesion increment specifically includes: determining it based on the shear strength, diameter, and circumferential and longitudinal spacing of the anchor bolt in the surrounding rock.

3. The method according to claim 1, characterized in that, In step S2, the calculation of the initial elastic modulus and the deteriorated elastic modulus of the anchor bolt and surrounding rock composite structure specifically includes: treating the anchor bolt and surrounding rock as composite materials, and calculating the initial elastic modulus and the deteriorated elastic modulus of the composite structure based on the initial and deteriorated elastic modulus of the surrounding rock, the elastic modulus and cross-sectional area of ​​the anchor bolt material, and the anchor bolt spacing, respectively, and setting the anchor bolt to not affect the Poisson's ratio of the surrounding rock in the calculation.

4. The method according to claim 1, characterized in that, In step S2, the calculation of the equivalent support reaction force specifically includes: converting the prestress applied by a single prestressed anchor rod or anchor cable into a uniformly distributed pressure acting on the support boundary based on its circumferential and longitudinal spacing.

5. The method according to claim 1, characterized in that, In step S4, the calculation of the rock mass strength safety factor specifically includes: comparing the total cohesion of the reinforced surrounding rock, the shear strength determined by the shear surface normal stress and internal friction angle considering the contribution of the equivalent support reaction force, with the average shear stress; wherein, the average shear stress is calculated by the modified pressure arch theory, and the load reduction effect of the equivalent support reaction force on the pressure arch is taken into account.

6. The method according to claim 1, characterized in that, In step S4, the calculation of the anchoring system efficiency coefficient specifically includes: comparing the shear resistance provided per unit area of ​​the anchor system with the rock mass shear requirements, and verifying the cooperative working ability of the anchor and the surrounding rock within the elastic deformation range, and taking the smaller value of the two results as the coefficient.

7. The method according to claim 1, characterized in that, In step S4, the calculation of the comprehensive deformation stability coefficient specifically includes: by comparing the total work of the support system, which consists of the work done by the equivalent support reaction force and the incremental elastic energy of the composite body, with the maximum elastic deformation energy of the bearing arch itself, the deformation stability of the system is evaluated from the perspective of energy balance.

8. A system for calculating the strength of surrounding rock based on the equivalent support reaction of prestressed anchor bolts, used to implement the method for calculating the strength of surrounding rock based on the equivalent support reaction of prestressed anchor bolts as described in any one of claims 1-7, characterized in that, include: The parameter input and management module is used to receive and store the initial mechanical parameters of the surrounding rock, the geometric and excavation parameters of the tunnel, and the design parameters of the anchor bolt support input by the user. A multi-dimensional effect calculation engine is connected to the parameter input and management module, used to call stored parameters and perform core calculations; The comprehensive safety assessment and output module is connected to the multi-dimensional effect calculation engine. It receives the safety factor, synthesizes it into the final surrounding rock strength safety factor through the built-in comprehensive quantification model, and outputs the stability level assessment result and visualization report.

9. The system according to claim 8, characterized in that, The multi-dimensional effect calculation engine includes: The load-bearing arch modeling submodule is used to automatically define the loosened zone and construct a hingeless arch calculation model of the rock load-bearing arch by calling numerical simulation results through an external interface based on the input excavation parameters, and generating its geometric properties and load information. The parameter enhancement calculation submodule is used to synchronously execute and output the calculation of cohesion increment, initial and deteriorated elastic modulus of the anchor bolt surrounding rock composite structure, and equivalent support reaction force based on the input anchor bolt support design parameters. The safety factor analysis submodule is connected to the parameter enhancement calculation submodule and the bearing arch modeling submodule, and is used to calculate the rock mass strength safety factor, anchoring system effectiveness coefficient and comprehensive deformation stability coefficient in parallel.

10. The system according to claim 9, characterized in that, The system also includes a support scheme optimization suggestion module, which is connected to the comprehensive safety assessment and output module. This module is used to analyze the final surrounding rock strength safety factor. If the final surrounding rock strength safety factor does not meet the requirements, optimization suggestions are automatically generated based on a preset rule base.

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