Method and device for evaluating stability of surrounding rock

Abstract

The application discloses a kind of surrounding rock stability evaluation method and device, the method of the application includes according to tunnel construction site data to establish the construction model of simulating tunnel construction;Based on the construction model, the main evaluation index and secondary evaluation index of tunnel surrounding rock are obtained, the main evaluation index includes surrounding rock safety factor and surrounding rock deformation value, and the secondary evaluation index includes initial support structure stress value and plastic zone distribution situation;Whether surrounding rock safety factor, surrounding rock deformation value, initial support structure stress value, plastic zone distribution situation meet index evaluation standard is judged respectively;The stability of tunnel surrounding rock is evaluated according to the result of judgment.The application solves how to more accurately evaluate the stability of tunnel surrounding rock.

Description

Technical Field

[0001] This application relates to the field of civil engineering technology, and more specifically, to a method and apparatus for evaluating the stability of surrounding rock. Background Technology

[0002] With the rapid development of my country's transportation industry, the number of tunnel construction projects is increasing, and the issues of tunnel safety construction and management are receiving more and more attention. How to reasonably evaluate the stability of the surrounding rock during tunnel construction is particularly important. Furthermore, in terms of tunnel design, the primary goal is to ensure the safety and stability of the surrounding rock and support structure after excavation and support. The stability evaluation of the tunnel surrounding rock is the theoretical basis for tunnel design and construction, directly determining the project's economy and safety. Accurately evaluating the stability of the tunnel surrounding rock can provide a scientific basis for preventing and controlling rock instability and failure. Therefore, how to accurately evaluate the stability of the tunnel surrounding rock is an urgent problem to be solved. Summary of the Invention

[0003] The main purpose of this application is to provide a method and apparatus for evaluating the stability of surrounding rock, and to solve the problem of how to more accurately evaluate the stability of surrounding rock in tunnels.

[0004] To achieve the above objectives, according to the first aspect of this application, a method for evaluating the stability of surrounding rock is provided.

[0005] The method for evaluating the stability of surrounding rock according to this application includes: establishing a construction model simulating tunnel construction based on data from the tunnel construction site; obtaining primary and secondary evaluation indicators for the tunnel surrounding rock based on the construction model, wherein the primary evaluation indicators include the surrounding rock safety factor and the surrounding rock deformation value, and the secondary evaluation indicators include the initial support structure stress value and the distribution of the plastic zone; determining whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the distribution of the plastic zone meet the evaluation criteria; and evaluating the stability of the tunnel surrounding rock based on the results of the determination.

[0006] Optionally, evaluating the stability of the tunnel surrounding rock based on the judgment result includes: if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the evaluation criteria, then the tunnel surrounding rock is determined to be unstable; if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the evaluation criteria, then the tunnel surrounding rock is determined to have an instability risk within a preset time period; if both the surrounding rock safety factor and the surrounding rock deformation value meet the evaluation criteria, and the initial support structure stress value or the plastic zone distribution does not meet the evaluation criteria, then the tunnel surrounding rock needs to have its initial support strengthened; if both the surrounding rock safety factor and the surrounding rock deformation value meet the evaluation criteria, and the initial support structure stress value and the plastic zone distribution also meet the evaluation criteria, then the tunnel surrounding rock is determined to be stable.

[0007] Optionally, obtaining the primary and secondary evaluation indicators of the tunnel surrounding rock based on the construction model includes: calculating the safety factor of the surrounding rock according to the strength reduction factor method; monitoring the displacement of the surrounding rock at typical tunnel sections in the construction model and obtaining the peak value of the surrounding rock deformation based on the monitoring data; monitoring the stress of the initial support structure in the construction model and obtaining the stress value of the initial support structure; and determining the distribution of the plastic zone according to the distribution cloud map of the plastic zone of the surrounding rock corresponding to the construction model.

[0008] Optionally, determining whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the plastic zone distribution meet the evaluation criteria includes: determining whether the surrounding rock safety factor is greater than the standard value of the surrounding rock safety factor in the evaluation criteria; determining whether the peak value of the surrounding rock deformation is less than the peak value of the surrounding rock deformation in the evaluation criteria; determining whether the initial support structure stress value is less than the stress limit value of the support structure in the evaluation criteria; and determining whether the plastic zone distribution meets the requirement of no plastic zone penetration in the evaluation criteria.

[0009] Optionally, the step of calculating the surrounding rock safety factor according to the strength reduction factor method includes: selecting any reduction factor as the initial strength reduction factor, reducing the strength parameters of the tunnel surrounding rock according to the initial strength reduction factor; using the reduced strength parameters as calculation parameters for finite element calculation; if the finite element calculation converges, increasing the initial strength reduction factor according to a preset increase principle, and reducing the strength parameters again according to the increased initial strength reduction factor; using the re-reduced strength parameters as calculation parameters for the finite element calculation, and determining the strength reduction factor corresponding to the convergence and non-convergence boundary of the finite element calculation as the surrounding rock safety factor.

[0010] Optionally, the step of establishing a construction model simulating tunnel construction based on tunnel construction site data includes: acquiring the tunnel construction site data; and establishing the construction model based on the simulation software FLAC3D and the tunnel construction site data.

[0011] To achieve the above objectives, according to a second aspect of this application, a device for evaluating the stability of surrounding rock is provided.

[0012] The surrounding rock stability evaluation device according to this application includes: a setup unit for setting up a construction model simulating tunnel construction based on tunnel construction site data; an acquisition unit for acquiring primary and secondary evaluation indicators of the tunnel surrounding rock based on the construction model, wherein the primary evaluation indicators include the surrounding rock safety factor and the surrounding rock deformation value, and the secondary evaluation indicators include the initial support structure stress value and the distribution of the plastic zone; a judgment unit for judging whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the distribution of the plastic zone meet the indicator evaluation criteria; and an evaluation unit for evaluating the stability of the tunnel surrounding rock based on the judgment results.

[0013] Optionally, the evaluation unit includes: a first evaluation module, used to determine that the tunnel surrounding rock is unstable if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the index evaluation standard; a second evaluation module, used to determine that the tunnel surrounding rock has an instability risk within a preset time period if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the index evaluation standard; a third evaluation module, used to determine that the tunnel surrounding rock needs to strengthen initial support if both the surrounding rock safety factor and the surrounding rock deformation value meet the index evaluation standard, and the initial support structure stress value or the plastic zone distribution does not meet the index evaluation standard; and a fourth evaluation module, used to determine that the tunnel surrounding rock is stable if both the surrounding rock safety factor and the surrounding rock deformation value meet the index evaluation standard, and the initial support structure stress value and the plastic zone distribution also meet the index evaluation standard.

[0014] Optionally, the acquisition unit includes: a first acquisition module, used to calculate the surrounding rock safety factor according to the strength reduction factor method; a second acquisition module, used to monitor the surrounding rock displacement of a typical tunnel section in the construction model, and obtain the peak value of the surrounding rock deformation based on the monitoring data; a third acquisition module, used to monitor the stress of the initial support structure in the construction model, and obtain the stress value of the initial support structure; and a fourth acquisition module, used to determine the distribution of the plastic zone based on the distribution cloud map of the plastic zone of the surrounding rock corresponding to the construction model.

[0015] Optionally, the judgment unit includes: a first judgment module, used to judge whether the surrounding rock safety factor is greater than the standard value of the surrounding rock safety factor in the index evaluation standard; a second judgment module, used to judge whether the peak value of the surrounding rock deformation is less than the peak value of the surrounding rock deformation in the index evaluation standard; a third judgment module, used to judge whether the stress value of the initial support structure is less than the stress limit value of the support structure in the index evaluation standard; and a fourth judgment module, used to judge whether the distribution of the plastic zone meets the requirement of no plastic zone penetration in the index evaluation standard.

[0016] Optionally, the first acquisition module is configured to: select any reduction coefficient as the initial strength reduction coefficient, reduce the strength parameters of the tunnel surrounding rock according to the initial strength reduction coefficient; use the reduced strength parameters as calculation parameters for finite element calculation; if the finite element calculation converges, increase the initial strength reduction coefficient according to a preset increase principle, and re-reduce the strength parameters according to the increased initial strength reduction coefficient; use the re-reduced strength parameters as calculation parameters for the finite element calculation, and determine the strength reduction coefficient corresponding to the convergence and non-convergence boundary of the finite element calculation as the surrounding rock safety factor.

[0017] Optionally, the establishment unit includes: a fifth acquisition module for acquiring the tunnel construction site data; and an establishment module for establishing the construction model based on the simulation software FLAC3D and the tunnel construction site data.

[0018] To achieve the above objectives, according to a third aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing the computer to perform the surrounding rock stability evaluation method according to any one of the first aspects above.

[0019] To achieve the above objectives, according to a fourth aspect of this application, an electronic device is provided, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to cause the at least one processor to perform the rock mass stability evaluation method described in any one of the first aspects above.

[0020] In the surrounding rock stability evaluation method and apparatus of this application embodiment, a construction model simulating tunnel construction is first established based on tunnel construction site data. Then, based on the construction model, the primary evaluation indicators of the tunnel surrounding rock—the surrounding rock safety factor and the surrounding rock deformation value—and the secondary evaluation indicators—the initial support structure stress value and the distribution of the plastic zone—are obtained. Next, it is determined whether the surrounding rock safety factor, surrounding rock deformation value, initial support structure stress value, and plastic zone distribution meet the indicator evaluation standards. The stability of the tunnel surrounding rock is evaluated based on the judgment results. It can be seen that this application embodiment uses multiple parameters—deformation, stress, plastic zone conditions, and the surrounding rock safety factor—as indicators to comprehensively judge the surrounding rock stability, resulting in more accurate and effective results. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:

[0022] Figure 1 This is a flowchart of a method for evaluating the stability of surrounding rock according to an embodiment of this application;

[0023] Figure 2 This is a schematic diagram of a distribution cloud map of the plastic zone of surrounding rock according to an embodiment of this application;

[0024] Figure 3 This is a block diagram of a surrounding rock stability evaluation device provided according to an embodiment of this application;

[0025] Figure 4 This is a block diagram of another surrounding rock stability evaluation device provided according to an embodiment of this application. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0027] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] According to embodiments of this application, a method for evaluating the stability of surrounding rock is provided, such as... Figure 1 As shown, the method includes the following steps S101-S104: S101. Establish a construction model simulating tunnel construction based on tunnel construction site data; S102. Obtain the main evaluation index and secondary evaluation index of the tunnel surrounding rock based on the construction model; the main evaluation index includes the surrounding rock safety factor and the surrounding rock deformation value, and the secondary evaluation index includes the initial support structure stress value and the distribution of the plastic zone; S103. Determine whether the surrounding rock safety factor, surrounding rock deformation value, initial support structure stress value, and plastic zone distribution meet the index evaluation criteria; S104. Evaluate the stability of the tunnel surrounding rock based on the judgment results.

[0030] In step S101, the tunnel construction site data includes actual construction data such as tunnel rock mass type, tunnel specifications, support structure, support parameters, construction step length, and construction procedures. After obtaining the tunnel construction site data, a construction model simulating tunnel construction can be established based on simulation software. Specifically, this application embodiment provides a method for establishing a construction model simulating tunnel construction: FLAC3D (Fast Lagrangian Analysis of Continua) is used for tunnel excavation simulation. The calculation model adopts a stratum-structure model, where the strata and initial tunnel support are simulated using Zone elements, anchor bolts are simulated using Cable elements, arch frames are simulated using Beam elements, and rock mass and concrete are simulated using 8-node 6-sided solid elements. The support measures applied in actual engineering are used as the model's support parameters. The model excavates in 1-meter units, and in conjunction with actual engineering, 1.8 meters is one construction step length. The anchor bolt and arch frame construction distance from the tunnel face is 6 meters, and the shotcrete range is 270°, 60 meters from the tunnel face. The model construction sequence is as follows: tunnel excavation → installation of anchor bolts and arch frames after excavating 6m → installation of shotcrete after excavating 60m. FLAC3D is a simulation software capable of simulating the three-dimensional structural stress characteristics and plastic flow analysis of soil, rock, and other materials, as well as fitting the actual structure by adjusting the polyhedral elements in the three-dimensional mesh. It should be noted that in practical applications, other simulation tools capable of building tunnel construction models can also be used; this application embodiment does not impose any limitations. Furthermore, the specific parameters in the above examples are determined based on the actual construction process in practical applications.

[0031] Step S102, obtaining the primary and secondary evaluation indicators of the tunnel surrounding rock based on the construction model, specifically includes the following steps: S1021. Calculate the safety factor of the surrounding rock using the strength reduction factor method; S1022. Monitor the displacement of the surrounding rock at typical tunnel sections in the construction model and obtain the peak value of the surrounding rock deformation based on the monitoring data; S1023. Monitor the stress of the initial support structure in the construction model and obtain the stress value of the initial support structure; S1024. Determine the distribution of the plastic zone based on the plastic zone distribution cloud map of the surrounding rock corresponding to the construction model. In specific applications, there is no strict requirement for the order of steps S1021-S1024, as long as the primary and secondary evaluation indicators are obtained.

[0032] In S1021, the specific implementation of calculating the surrounding rock safety factor using the strength reduction factor method is as follows: Any reduction factor is selected as the initial strength reduction factor; the strength parameters of the tunnel surrounding rock are reduced according to the initial strength reduction factor; the reduced strength parameters are used as calculation parameters for finite element analysis (FEM); if the FEM calculation converges, the initial strength reduction factor is increased according to a preset increase principle, and the strength parameters are re-reduced according to the increased initial strength reduction factor; the re-reduced strength parameters are used as calculation parameters for FEM; the strength reduction factor corresponding to the convergence and non-convergence boundaries of the FEM calculation is determined as the surrounding rock safety factor. The strength parameters include cohesion and internal friction angle, and the strength parameters are calculated according to formula c. e =c / F, The reduction is performed, where c is the cohesive force in the formula, and the unit is MPa; The internal friction angle is expressed in degrees; F is the reduction factor; c e , Let's consider a new set of cohesion and internal friction angles. Finite element analysis (FEM) calculations can be performed using FEM software. After the calculation, if the program (FEM program) converges, the initial strength reduction factor is increased according to a preset increase principle. The preset increase principle is manually set; it can be a fixed value for each increase, such as 20%, or an arbitrary value chosen based on experience. After increasing the initial strength reduction factor, the strength parameters are re-reduced according to the increased initial strength reduction factor, also following the formula above. This reduction and FEM calculation are repeated cyclically until the strength reduction factor at the convergence / non-convergence boundary is determined as the surrounding rock safety factor.

[0033] In S1022, the displacement of the surrounding rock at typical tunnel sections in the construction model is monitored, and the peak value of the surrounding rock deformation is obtained based on the monitoring data. Specifically, this includes: selecting sections with larger deformation to monitor the displacement in three directions: crown, bottom, and horizontal, obtaining crown settlement data, bottom heave data, and horizontal convergence data. The peak values ​​of crown settlement (maximum), bottom heave (maximum), and horizontal convergence (maximum) are then analyzed and determined. It should be noted that when obtaining the peak value of the surrounding rock deformation, the section with larger deformation is selected as the typical section for monitoring and obtaining relevant data. Other indicators are also obtained based on the section with larger deformation. The stability of the section with larger deformation should be the worst compared to other sections. If the surrounding rock stability evaluation indicators obtained based on the section with larger deformation can meet the standards for surrounding rock stability, then all surrounding rock is also stable.

[0034] In S1023, the stress of the initial support structure in the construction model is monitored to obtain the stress values ​​of the initial support structure. Specifically, assuming that the initial support structure includes three structures: arch frame, anchor bolts, and shotcrete, the forces on the arch frame, anchor bolts, and shotcrete are monitored to obtain the corresponding stress values. The arch frame yields compressive stress values, the anchor bolts yield tensile and compressive stress values, and the shotcrete yields the maximum and minimum principal stress values.

[0035] In S1024, the distribution of the plastic zone is determined based on the distribution cloud map of the surrounding rock corresponding to the construction model. Specifically, the plastic zone of the surrounding rock refers to the region where the pressure from the load on the upper part of the surrounding rock exceeds the ultimate bearing capacity of the rock mass, causing irreversible deformation and yielding. Different types of rock masses have different ultimate bearing capacities. The simulation software generates a distribution cloud map of the plastic zone of the surrounding rock based on monitoring data of rock mass deformation, from which the distribution of the plastic zone can be determined. Specifically, as shown... Figure 2 The diagram shown is a schematic representation of the distribution cloud map of the plastic zone in surrounding rock. The right side is the distribution cloud map, where points have coordinates, thus defining the extent of the plastic zone. The left side provides an explanation of the diagram, where the shear-p plastic zone is continuous; shear represents shear failure, n stands for now (occurring in the current cycle), and p stands for previous (occurring in a previous cycle). Figure 2 It can be determined that the plastic zone is uniform, with a larger plastic zone at the arch crown. During tunnel excavation, the surrounding rock underwent continuous plastic shear deformation, resulting in a continuous tunnel. It should also be noted that the plastic zone obtained from the simulation software cannot accurately represent the final distribution of the plastic zone; rather, it is a record and overlay of historically occurring plastic zone ranges. Therefore, the distribution of the plastic zone is only considered a secondary evaluation indicator.

[0036] After obtaining the primary and secondary evaluation indicators in step S102, proceed to step S103 to determine whether each indicator meets the indicator evaluation criteria. The indicator evaluation criteria specify the evaluation standards for different indicators; when evaluating each indicator, the corresponding evaluation standard is selected. The evaluation standards for each indicator are based on relevant industry standards and manuals, such as GB50086, the "Geotechnical Engineering Monitoring Manual," the "People's Republic of China Electric Power Industry Standard" (DL / T55415-2009), and the provisions in Appendix M1 of the "Technical Specification for Engineering Geological Exploration of Underground Structures in Water Conservancy and Hydropower Projects." Specifically, determining whether the surrounding rock safety factor meets the evaluation criteria involves checking if the surrounding rock safety factor is greater than the standard value in the evaluation criteria. If it is greater, the surrounding rock safety factor meets the evaluation criteria; otherwise, it does not. Similarly, determining whether the surrounding rock deformation value meets the evaluation criteria involves checking if the peak value of the surrounding rock deformation is less than the peak value of the surrounding rock deformation in the evaluation criteria. The peak values ​​include the peak settlement of the arch, the peak heave at the base, and the peak horizontal convergence. Each peak value is compared with its corresponding peak value in the evaluation criteria. If all three peak values ​​are less than the corresponding peak value in the evaluation criteria, then the surrounding rock safety factor meets the criteria. The peak value of the surrounding rock deformation must meet the evaluation criteria; otherwise, the peak value of the surrounding rock deformation must not meet the evaluation criteria. To determine whether the initial support structure stress value meets the evaluation criteria, specifically, it must be determined whether the initial support structure stress value is less than the stress limit value of the support structure in the evaluation criteria. Different construction projects may not include various types of initial support structures. During the evaluation, the stress value of each support structure must be compared with its corresponding stress limit value in the evaluation criteria. If the stress value of each support structure is less than the corresponding stress limit value in the evaluation criteria, then the initial support structure stress value meets the evaluation criteria; otherwise, the initial support structure stress value meets the evaluation criteria. To determine whether the distribution of the plastic zone meets the evaluation criteria, specifically, it must be determined whether the distribution of the plastic zone meets the requirement of "no plastic zone penetration" in the evaluation criteria.

[0037] After completing the judgment of each indicator in step S103, proceed to step S104 to evaluate the stability of the tunnel surrounding rock based on the judgment results. The evaluation criteria are as follows: if neither of the two main evaluation indicators meets the safety requirements, the surrounding rock is considered unstable; if one of them does not meet the requirements, the surrounding rock is considered to have potential risks to long-term stability. If both main evaluation indicators meet the safety requirements, but at least one of the initial support structure stress and plastic zone distribution conditions does not meet the requirements, the initial support needs to be strengthened. The specific evaluation method in the embodiments of this application is as follows: If neither the surrounding rock safety factor nor the surrounding rock deformation value meets the evaluation criteria, the tunnel surrounding rock is determined to be unstable; if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the evaluation criteria, the tunnel surrounding rock is determined to have an instability risk within a preset time period, where the preset time period is usually a relatively long period and cannot be given a fixed time period, which is a qualitative description, that is, the tunnel surrounding rock has a long-term instability risk; if both the surrounding rock safety factor and the surrounding rock deformation value meet the evaluation criteria, but the initial support structure stress value or plastic zone distribution does not meet the evaluation criteria, the tunnel surrounding rock needs to strengthen the initial support; if both the surrounding rock safety factor and the surrounding rock deformation value meet the evaluation criteria, and the initial support structure stress value and plastic zone distribution also meet the evaluation criteria, the tunnel surrounding rock is determined to be stable.

[0038] In response to the above Figure 1 The method for evaluating the stability of surrounding rock in the paper is further explained in detail with reference to actual construction cases, as follows:

[0039] For the relatively soft and fractured Class IV and V surrounding rock, FLAC3D was used to simulate tunnel excavation. The calculation model adopted a stratum-structure model, in which the strata and initial tunnel support were simulated using Zone elements, anchor bolts using Cable elements, arch frames using Beam elements, and rock mass and concrete using 8-node hexahedral solid elements. The support measures used in actual engineering applications were used as the model's support parameters. The model excavated in 1-meter increments, and in accordance with actual engineering, 1.8-meter intervals were used for each construction step. The anchor bolt and arch frame were constructed 6 meters from the tunnel face, and the shotcrete range was 270°, 60 meters from the tunnel face. The model's construction sequence was: tunnel excavation → installation of anchor bolts and arch frames after excavating 6 meters → installation of shotcrete after excavating 60 meters.

[0040] The calculation results of the section with larger deformation are selected as representative for analysis:

[0041] The surrounding rock deformation obtained from the numerical calculation results is symmetrically distributed, as shown in Table 1, which is a statistical table of surrounding rock deformation results. The maximum settlement of the arch is 88.1 mm, the maximum heave at the bottom is 71.9 mm, and the maximum horizontal convergence is 160.3 mm, indicating that the surrounding rock deformation is relatively large. The allowable convergence value around the tunnel in Table 1 is the peak value of surrounding rock deformation in the index evaluation criteria in the above embodiment.

[0042] Table 1 Statistical table of surrounding rock deformation results

[0043]

[0044] Figure 2 The distribution cloud map of the plastic zone of the surrounding rock is used to determine the distribution of the plastic zone as follows: the plastic zone ranges from 2.5 to 3.2 m, the plastic zone is uniform, the plastic zone is larger in the crown area, and the shear-p plastic zone is continuous.

[0045] The initial stress on the support structure is shown in Table 2, where: the maximum compressive stress of the arch frame is 68.71 MPa; the maximum tensile stress of the anchor bolt is 63.63 MPa; the stress of the shotcrete is relatively small, with a maximum principal stress of 0.003 MPa and a minimum principal stress of 2.18 MPa; the strength design values ​​in Table 2 are the stress limit values ​​of the support structure in the index evaluation criteria of the above embodiments.

[0046] Table 2 Statistical analysis of the initial support structure stress results

[0047]

[0048]

[0049] Based on the calculation results of the construction model, the analysis and evaluation of the surrounding rock stability are as follows:

[0050] 1) Regarding the deformation of the surrounding rock, the numerical calculation results show that before the secondary lining concrete was applied, the maximum settlement of the arch was 88.1 mm, which is greater than the allowable convergence value of 78 mm in the tunnel and does not meet the peak value of the surrounding rock deformation in the evaluation criteria; the maximum value of the bottom heave was 71.9 mm, which is less than 78 mm and meets the peak value of the surrounding rock deformation in the evaluation criteria; the maximum value of the horizontal convergence was 160.3 mm, which is greater than the allowable convergence value of 156 mm in the tunnel and does not meet the peak value of the surrounding rock deformation in the evaluation criteria.

[0051] 2) The plastic zone ranges from 2.5 to 3.2 m, and the shear-p plastic zone is connected, which does not meet the evaluation criteria.

[0052] 3) Regarding the stress on the initial support structure, calculation results show that the arch frame is under overall compression and the anchor rods are under overall tension. The maximum compressive stress of the arch frame is 68.71 MPa, which is less than 215 MPa, meeting the stress limit value of the support structure in the evaluation criteria. The maximum tensile stress of the anchor rods is 63.63 MPa, which is less than the anchor rod tensile strength of 360 MPa, meeting the stress limit value of the support structure in the evaluation criteria. The stress of the shotcrete is relatively low, with the maximum principal stress being 0.003 MPa, which is less than 1.3 MPa, meeting the stress limit value of the support structure in the evaluation criteria. The minimum principal stress is 2.18 MPa, which is less than 12.5 MPa, meeting the stress limit value of the support structure in the evaluation criteria. All structures of the initial support meet the safety requirements.

[0053] 4) Safety Factor Calculation. Based on the strength reduction factor method, the surrounding rock safety factor n = 2.68 was calculated using the FOS command in FLAC3D. This is greater than 1.25, indicating that the surrounding rock safety factor meets the evaluation criteria. Here, 1.25 is the standard value of the surrounding rock safety factor in the evaluation criteria of the above embodiment. 1.25 is the standard value of the surrounding rock safety factor for composite linings; for primary linings, the standard value of the surrounding rock safety factor is 1.3, meaning the surrounding rock safety factor can be less than 1.3. A value less than 1.3 indicates that the surrounding rock safety factor does not meet the evaluation criteria.

[0054] Based on the above results, the initial support structure stress value and surrounding rock safety factor both meet the evaluation criteria, while the surrounding rock deformation value and plastic zone distribution do not meet the evaluation criteria. In other words, one main indicator does not meet the evaluation criteria. Therefore, the evaluation result of surrounding rock stability is that there is a potential risk to the long-term stability of the surrounding rock.

[0055] In summary, the beneficial effects of the surrounding rock stability evaluation method of the embodiments of this application are summarized as follows:

[0056] 1. Numerical analysis, strength reduction method and field monitoring method were adopted to comprehensively judge the stability of the surrounding rock using parameters such as deformation, stress, plastic zone conditions and surrounding rock safety factor as indicators, and the results are more accurate and effective;

[0057] 2. The indicators proposed in this method for evaluating the stability of surrounding rock are simple and clear, and have good feasibility and applicability.

[0058] As can be seen from the above description, the surrounding rock stability evaluation method of this application first establishes a construction model simulating tunnel construction based on tunnel construction site data; then, based on the construction model, it obtains the main evaluation indicators of the tunnel surrounding rock, namely the surrounding rock safety factor and the surrounding rock deformation value, and the secondary evaluation indicators, namely the initial support structure stress value and the distribution of the plastic zone; then, it determines whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the distribution of the plastic zone meet the indicator evaluation criteria; and finally, it evaluates the stability of the tunnel surrounding rock based on the judgment results. It can be seen that this application embodiment uses multiple parameters, including deformation, stress, plastic zone conditions, and the surrounding rock safety factor, as indicators to comprehensively judge the surrounding rock stability, resulting in more accurate and effective results.

[0059] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0060] According to embodiments of this application, a method for implementing the above is also provided. Figure 1-2 The method's surrounding rock stability evaluation device 200, such as Figure 3 As shown, the device includes: a setup unit 21, used to establish a construction model simulating tunnel construction based on tunnel construction site data; an acquisition unit 22, used to acquire primary and secondary evaluation indicators of the tunnel surrounding rock based on the construction model, wherein the primary evaluation indicators include the surrounding rock safety factor and the surrounding rock deformation value, and the secondary evaluation indicators include the initial support structure stress value and the distribution of the plastic zone; a judgment unit 23, used to judge whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the distribution of the plastic zone meet the indicator evaluation criteria; and an evaluation unit 24, used to evaluate the stability of the tunnel surrounding rock based on the judgment results.

[0061] Specifically, the detailed process by which each unit and module in the device of this application implements its function can be found in the relevant description in the method embodiment, and will not be repeated here.

[0062] As can be seen from the above description, in the surrounding rock stability evaluation device of this application embodiment, a construction model simulating tunnel construction is first established based on tunnel construction site data; then, based on the construction model, the main evaluation indicators of the tunnel surrounding rock, the surrounding rock safety factor and the surrounding rock deformation value, and the secondary evaluation indicators, the initial support structure stress value and the distribution of the plastic zone, are obtained; then, it is determined whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the distribution of the plastic zone meet the indicator evaluation standards; and the stability of the tunnel surrounding rock is evaluated based on the judgment results. It can be seen that this application embodiment uses multiple parameters, including deformation, stress, plastic zone conditions, and the surrounding rock safety factor, as indicators to comprehensively judge the stability of the surrounding rock, resulting in more accurate and effective results.

[0063] Furthermore, such as Figure 4 As shown, the evaluation unit 24 includes: a first evaluation module 241, used to determine that the tunnel surrounding rock is unstable if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the index evaluation standard; a second evaluation module 242, used to determine that the tunnel surrounding rock has an instability risk within a preset time period if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the index evaluation standard; a third evaluation module 243, used to determine that the tunnel surrounding rock needs to strengthen the initial support if both the surrounding rock safety factor and the surrounding rock deformation value meet the index evaluation standard, and the initial support structure stress value or the plastic zone distribution does not meet the index evaluation standard; and a fourth evaluation module 244, used to determine that the tunnel surrounding rock is stable if both the surrounding rock safety factor and the surrounding rock deformation value meet the index evaluation standard, and the initial support structure stress value and the plastic zone distribution also meet the index evaluation standard.

[0064] Furthermore, such as Figure 4 As shown, the acquisition unit 22 includes: a first acquisition module 221, used to calculate the surrounding rock safety factor according to the strength reduction factor method; a second acquisition module 222, used to monitor the surrounding rock displacement of a typical tunnel section in the construction model, and obtain the peak value of the surrounding rock deformation based on the monitoring data; a third acquisition module 223, used to monitor the stress of the initial support structure in the construction model, and obtain the stress value of the initial support structure; and a fourth acquisition module 224, used to determine the distribution of the plastic zone according to the distribution cloud map of the plastic zone of the surrounding rock corresponding to the construction model.

[0065] Furthermore, such as Figure 4As shown, the judgment unit 23 includes: a first judgment module 231, used to judge whether the surrounding rock safety factor is greater than the standard value of the surrounding rock safety factor in the index evaluation standard; a second judgment module 232, used to judge whether the peak value of the surrounding rock deformation is less than the peak value of the surrounding rock deformation in the index evaluation standard; a third judgment module 233, used to judge whether the stress value of the initial support structure is less than the stress limit value of the support structure in the index evaluation standard; and a fourth judgment module 234, used to judge whether the distribution of the plastic zone meets the requirement of no plastic zone penetration in the index evaluation standard.

[0066] Furthermore, such as Figure 4 As shown, the first acquisition module 221 is used to: select any reduction coefficient as the initial strength reduction coefficient, reduce the strength parameters of the tunnel surrounding rock according to the initial strength reduction coefficient; use the reduced strength parameters as calculation parameters for finite element calculation; if the finite element calculation converges, increase the initial strength reduction coefficient according to a preset increase principle, and reduce the strength parameters again according to the increased initial strength reduction coefficient; use the re-reduced strength parameters as calculation parameters for the finite element calculation, and determine the strength reduction coefficient corresponding to the convergence and non-convergence boundary of the finite element calculation as the surrounding rock safety factor.

[0067] Furthermore, such as Figure 4 As shown, the establishment unit 21 includes: a fifth acquisition module 211, used to acquire the tunnel construction site data; and an establishment module 212, used to establish the construction model based on the simulation software FLAC3D and the tunnel construction site data.

[0068] Specifically, the detailed process by which each unit and module in the device of this application implements its function can be found in the relevant description in the method embodiment, and will not be repeated here.

[0069] According to an embodiment of this application, a computer-readable storage medium is also provided, characterized in that the computer-readable storage medium stores computer instructions, which are used to cause the computer to execute the surrounding rock stability evaluation method in the above method embodiments.

[0070] According to an embodiment of this application, an electronic device is also provided, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to cause the at least one processor to perform the surrounding rock stability evaluation method in the above method embodiments.

[0071] Obviously, those skilled in the art should understand that the modules or steps of this application described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device, or fabricating them separately as individual integrated circuit modules, or fabricating multiple modules or steps as a single integrated circuit module. Thus, this application is not limited to any particular combination of hardware and software.

[0072] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for evaluating the stability of surrounding rock, characterized in that, The method includes: A construction model simulating tunnel construction was established based on data from the tunnel construction site. Based on the construction model, the main evaluation index and secondary evaluation index of the tunnel surrounding rock are obtained. The main evaluation index includes the surrounding rock safety factor and the surrounding rock deformation value. The secondary evaluation index includes the initial support structure stress value and the distribution of the plastic zone. Determine whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the plastic zone distribution meet the evaluation criteria. If neither the surrounding rock safety factor nor the surrounding rock deformation value meets the evaluation criteria, then the surrounding rock of the tunnel is determined to be unstable. If the surrounding rock safety factor or the surrounding rock deformation value does not meet the evaluation criteria, then it is determined that the tunnel surrounding rock has an unstable risk within a preset time period. If the surrounding rock safety factor and the surrounding rock deformation value both meet the evaluation criteria, and the initial support structure stress value or the plastic zone distribution does not meet the evaluation criteria, then it is determined that the tunnel surrounding rock needs to be reinforced with initial support. If the surrounding rock safety factor and the surrounding rock deformation value both meet the evaluation criteria, and the initial support structure stress value and the distribution of the plastic zone also meet the evaluation criteria, then the tunnel surrounding rock is determined to be stable.

2. The method for evaluating the stability of surrounding rock according to claim 1, characterized in that, The main and secondary evaluation indicators for tunnel surrounding rock obtained based on the construction model include: The safety factor of the surrounding rock is calculated using the strength reduction factor method. The displacement of the surrounding rock in a typical section of the tunnel in the construction model is monitored, and the peak value of the surrounding rock deformation is obtained based on the monitoring data. The stress of the initial support structure in the construction model is monitored to obtain the stress value of the initial support structure. The distribution of the plastic zone is determined based on the cloud map of the plastic zone distribution of the surrounding rock corresponding to the construction model.

3. The method for evaluating the stability of surrounding rock according to claim 2, characterized in that, The steps of determining whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the plastic zone distribution meet the evaluation criteria include: Determine whether the surrounding rock safety factor is greater than the standard value of the surrounding rock safety factor in the index evaluation standard; and, Determine whether the peak value of the surrounding rock deformation is less than the peak value of the surrounding rock deformation in the index evaluation standard; and, Determine whether the initial stress value of the support structure is less than the stress limit value of the support structure in the evaluation criteria; and Determine whether the distribution of the plastic zone meets the evaluation criteria of the index, specifically the requirement that no plastic zone penetration occurs.

4. The method for evaluating the stability of surrounding rock according to claim 2, characterized in that, The calculation of the surrounding rock safety factor based on the strength reduction factor method includes: Select any reduction factor as the initial strength reduction factor, and reduce the strength parameters of the tunnel surrounding rock according to the initial strength reduction factor; The reduced strength parameters are used as calculation parameters for finite element analysis. If the finite element calculation converges, the initial strength reduction factor is increased according to the preset increase principle, and the strength parameter is reduced again according to the increased initial strength reduction factor. The strength parameters after re-reduction are used as calculation parameters for the finite element calculation, and the strength reduction coefficients corresponding to the convergence and non-convergence boundaries of the finite element calculation are determined as the surrounding rock safety factor.

5. The method for evaluating the stability of surrounding rock according to claim 1, characterized in that, The construction model for simulating tunnel construction based on on-site tunnel construction data includes: Obtain the tunnel construction site data; The construction model was established based on the simulation software FLAC3D and the tunnel construction site data.

6. A device for evaluating the stability of surrounding rock, characterized in that, The device includes: Establish a unit to create a construction model simulating tunnel construction based on data from the tunnel construction site; The acquisition unit is used to acquire the main evaluation index and secondary evaluation index of the tunnel surrounding rock based on the construction model. The main evaluation index includes the surrounding rock safety factor and the surrounding rock deformation value. The secondary evaluation index includes the initial support structure stress value and the distribution of the plastic zone. The judgment unit is used to determine whether the surrounding rock safety factor, the surrounding rock deformation value, the initial support structure stress value, and the plastic zone distribution meet the index evaluation criteria. An evaluation unit is used to evaluate the stability of the tunnel surrounding rock based on the judgment result. The evaluation unit specifically includes: The first evaluation module is used to determine that the tunnel surrounding rock is unstable if neither the surrounding rock safety factor nor the surrounding rock deformation value meets the index evaluation criteria. The second evaluation module is used to determine that the surrounding rock of the tunnel has an unstable risk within a preset time period if the surrounding rock safety factor or the surrounding rock deformation value does not meet the index evaluation criteria. The third evaluation module is used to determine that the tunnel surrounding rock needs to be reinforced in the initial support if the surrounding rock safety factor and the surrounding rock deformation value both meet the index evaluation criteria, but the initial support structure stress value or the plastic zone distribution does not meet the index evaluation criteria. The fourth evaluation module is used to determine the stability of the tunnel surrounding rock if the surrounding rock safety factor and the surrounding rock deformation value both meet the index evaluation criteria, and the initial support structure stress value and the plastic zone distribution also meet the index evaluation criteria.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the rock stability evaluation method according to any one of claims 1 to 5.

8. An electronic device, characterized in that, include: At least one processor; The system includes a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to cause the at least one processor to perform the rock stability evaluation method according to any one of claims 1 to 5.

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