A special-shaped grouting anchor rod supporting system and a type selection construction method

Abstract

The application provides a special-shaped grouting anchor rod supporting system and a selection construction method, and belongs to the technical field of underground engineering. The method first acquires physical and mechanical parameters of surrounding rock, a grouting body and a supporting structure; then a plane strain mechanical analysis model of a tunnel-grouting body-surrounding rock-supporting structure is established; based on the model, a finite element numerical simulation calculation model is established to analyze the mechanical response of various special-shaped grouting body sections under the same grouting amount; then, the mechanical response data are used as a judgment index, a multi-index decision method such as an analytic hierarchy process is adopted, and the optimal grouting body section form is comprehensively evaluated and optimized; finally, according to the optimized section, the anchor rod arrangement and grouting parameters are determined for construction to form a closed special-shaped grouting body. The application adopts the special-shaped grouting anchor rod supporting system and the selection construction method, realizes active optimization of the stress distribution of the surrounding rock, effectively controls the development of the plastic zone and the tunnel deformation, and improves the supporting effect and economy.

Description

Technical Field

[0001] This invention relates to the field of underground engineering technology, and in particular to a non-circular grouting anchor support system and its selection and construction method. Background Technology

[0002] After long-term development, rock bolt support technology has formed various support theories, including suspension theory, composite beam theory, span reduction theory, maximum horizontal stress theory, loosening ring support theory, and roadway butterfly failure theory. Practice has shown that rock bolts play a crucial role in maintaining the integrity of the surrounding rock, improving its overall stability, and enhancing its mechanical parameters. In this process, various support methods, such as slotted pipe rock bolts, cement mortar rock bolts, hollow grouting rock bolts, and drill-and-anchor rock bolts, have been developed and applied.

[0003] Grouting anchors typically use hollow steel pipes as their rods, which are then grouted through the pipes after being driven into the surrounding rock. This method effectively improves the physical and mechanical parameters of the surrounding rock and overcomes the insufficient anchoring force of ordinary mortar anchors, thus significantly enhancing the support effect. Therefore, it is widely used in tunnel engineering and mining engineering.

[0004] When tunnels are constructed using the mining method, the surrounding rock stress undergoes two redistribution processes: the first is due to the stress release caused by tunnel excavation, forming a secondary stress field; the second occurs after the initial support structures such as anchor bolts, shotcrete, steel mesh, and steel arch frames are installed, forming a tertiary stress field due to the interaction between the surrounding rock and the support structures.

[0005] Currently, there is considerable research on the theory and technology of grouting anchor support. Most of the findings are based on the concept of the surrounding rock-support characteristic curve, focusing on developing new grouting anchors suitable for different working conditions or evaluating the support effect. However, research on how to actively optimize the stress distribution around the tunnel through grouting anchor support, thereby inhibiting the development of plastic deformation in the surrounding rock, is still insufficient. Therefore, conducting research on grouting anchor support systems based on the stress redistribution concept has significant theoretical and practical value for promoting the advancement of tunnel initial support technology. Summary of the Invention

[0006] The purpose of this invention is to provide an irregular grouting anchor support system and a selection and construction method to solve the technical problem in the prior art that it is difficult to actively optimize the stress distribution around the tunnel and suppress the plastic deformation of the surrounding rock through grouting anchor support.

[0007] To achieve the above objectives, this invention provides a selection and construction method for an irregular grouting anchor support system, comprising the following steps:

[0008] Step S1: Obtain the physical and mechanical parameters of the surrounding rock, grouting body, and support structure within the current tunnel construction area;

[0009] Step S2: Based on the acquired physical and mechanical parameters, establish a plane strain mechanical analysis model of the tunnel-grouting body-surrounding rock-support structure;

[0010] Step S3: Based on the established plane strain mechanical analysis model of tunnel-grouting body-surrounding rock-support structure, establish a finite element numerical simulation calculation model to calculate the mechanical response of various preset irregular grouting body sections under the action of surrounding rock pressure under the same grouting volume conditions.

[0011] Step S4: Using mechanical response data as the judgment index, a multi-index decision analysis method is adopted to comprehensively evaluate different irregular grouting body cross-sectional forms, and select the optimal grouting body cross-sectional form accordingly.

[0012] Step S5: Based on the optimal grouting body cross-sectional shape selected, determine the arrangement parameters of the grouting anchors and the grouting parameters, and carry out construction to form a closed irregular grouting body in the surrounding rock of the tunnel.

[0013] Preferably, in step S1, the physical and mechanical parameters of the surrounding rock include elastic modulus, Poisson's ratio, internal friction angle, cohesion, surrounding rock pressure, and surrounding rock lateral pressure coefficient; the physical and mechanical parameters of the grouting body include elastic modulus, Poisson's ratio, internal friction angle, and cohesion; and the physical and mechanical parameters of the support structure include elastic modulus and Poisson's ratio.

[0014] Preferably, in step S2, the process of establishing the plane strain mechanical analysis model of the tunnel-grouting body-surrounding rock-support structure includes the following steps:

[0015] Step S21: Perform geometric simplification: simplify the three-dimensional tunnel construction problem into a plane strain problem;

[0016] Step S22: Based on the above simplified geometric model, set the load: set the surrounding rock pressure acting on the model as a uniformly distributed load that does not change with the tunnel size, and ignore the self-weight of the surrounding rock and the grouting body.

[0017] Step S23: Based on the obtained physical and mechanical parameters and load settings, define the constitutive relationship: define the surrounding rock and grout material as ideal elastic-plastic materials, and use the Drucker-Prager yield criterion as its plastic yield condition.

[0018] Step S24: Based on geometric simplification and constitutive relations, define the structural relations: assume that the grouting anchors are densely distributed to ensure that the grouting body formed is closed in a ring around the tunnel.

[0019] Preferably, in step S3, the various preset irregular grout body cross sections include annular, short teardrop, tall teardrop, short spindle, long spindle, curved triangle, triangle, umbrella, roly-poly, and oval.

[0020] Preferably, in step S3, the mechanical response includes the range of the plastic zone around the tunnel, the tunnel convergence deformation, and the stress of the support structure.

[0021] Preferably, in step S3, the process of establishing the finite element numerical simulation calculation model includes the following steps:

[0022] Step S31: Select and set elements: Use PLANE42 elements to simulate the surrounding rock and grouting body, and set its element option to plane strain; at the same time, use BEAM188 elements to simulate the support structure.

[0023] Step S32: Apply boundary conditions based on element settings: Apply a uniformly distributed load corresponding to the surrounding rock pressure and lateral pressure coefficient to the model boundary, and constrain the normal displacement of the model centerline to avoid rigid body displacement.

[0024] Preferably, in step S4, the multi-index decision analysis method is the Analytic Hierarchy Process (AHP), which includes the following steps:

[0025] Step S41: Construct a hierarchical model: Select the optimal grouting body cross section as the target layer, the mechanical response index as the criterion layer, and the cross section forms of each grouting body as the scheme layer.

[0026] Step S42: Based on the numerical simulation results of step S3, construct the judgment matrix of the scheme layer relative to the criterion layer;

[0027] Step S43: Based on expert scoring, construct the judgment matrix of the criterion layer relative to the target layer;

[0028] Step S44: Calculate the eigenvectors of each of the above judgment matrices and perform a consistency check;

[0029] Step S45: Based on the feature vectors calculated in step S44, calculate the total weight of each grouting body cross-section in the scheme layer relative to the target layer, and use this as a comprehensive evaluation index to select the cross-section with the highest total weight as the optimal scheme.

[0030] Preferably, in step S4, when the lateral pressure coefficient of the surrounding rock is less than or equal to 0.5, the optimal grouting body cross-section shape selected by the multi-index decision analysis method is oval.

[0031] Preferably, in step S5, the arrangement parameters of the grouting anchor bolts include the anchor bolt length and the spacing between the anchor bolts; the grouting parameters include the grouting pressure and the grouting holding time.

[0032] The present invention also provides an irregular grouting anchor support system designed and constructed using the method described above. The grouting body formed by the support system in the surrounding rock of the tunnel has a non-circular irregular cross-sectional shape.

[0033] Therefore, the present invention employs the above-mentioned irregular grouting anchor support system and selection and construction method, and the beneficial technical effects are as follows:

[0034] (1) Unlike traditional methods that rely on experience or form a homogeneous reinforcement ring, this invention establishes a plane strain mechanical model of the tunnel-grouting body-surrounding rock-support structure and uses numerical simulation to analyze the mechanical response of various irregular grouting body cross sections under the same grouting volume. This allows for a precise assessment of the influence of different cross-sectional shapes on the plastic zone, convergence deformation, and support stress of the surrounding rock. Furthermore, by using decision-making methods such as the Analytic Hierarchy Process (AHP), the irregular grouting body cross section that can optimally improve the stress state around the tunnel and reduce the development of the plastic zone is actively selected. This solves the technical gap in the prior art of "how to improve stress distribution and suppress plastic deformation through grouting anchor support".

[0035] (2) This invention provides a complete and quantitative selection and construction method, from parameter determination, model establishment, numerical simulation to section optimization and construction. This method transforms traditional empirical support design into a scientific decision-making process based on mechanical principles and numerical optimization. By optimizing irregular sections (such as oval sections under low lateral pressure coefficients), better support effects can be obtained with the same grouting volume. This means that while achieving the same safety standards, it is possible to reduce the amount of initial support materials used, thereby improving the support effect and providing the possibility of saving engineering costs. Attached Figure Description

[0036] Figure 1 A mechanical analysis model for the tunnel-grouting body-surrounding rock-support structure;

[0037] Figure 2 This is a simplified cross-sectional diagram of the grouting body in the numerical simulation calculation scheme, where, Figure 2 (a) in the text represents operating condition 1. Figure 2 (b) in the diagram represents operating condition 2. Figure 2 (c) in the diagram represents operating condition 3. Figure 2 (d) in the text refers to operating condition 4. Figure 2 (e) in the text refers to operating condition 5. Figure 2 (f) in the text refers to operating condition 6. Figure 2 (g) in the text refers to operating condition 7. Figure 2 (h) in the text refers to operating condition 8. Figure 2 In this context, (i) represents operating condition 9. Figure 2 (j) in the text represents operating condition 10;

[0038] Figure 3 The diagram shows the finite element geometric model, where... Figure 3 (a) in the model represents the entire model. Figure 3 (b) in the figure represents the cross-section of the grouting body. Figure 3 (c) in the diagram represents the support structure model;

[0039] Figure 4 Set up a simplified diagram for the boundary conditions of the finite element model;

[0040] Figure 5 The influence of mesh size in the finite element model on the stress calculation results of the surrounding rock around the tunnel;

[0041] Figure 6 This is a hierarchical diagram of the AHP (Analytic Hierarchy Process).

[0042] Figure 7 This is a simplified diagram of the anchor bolt arrangement based on the preferred cross-section of the circular tunnel grouting body;

[0043] Figure 8 This is a flowchart of the selection and construction method of an irregular grouting anchor support system according to the present invention. Detailed Implementation

[0044] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0046] Example 1

[0047] This embodiment describes the complete selection and construction process of an irregular grouting anchor support system based on the concept of surrounding rock stress redistribution, as follows: Figure 8 As shown.

[0048] 1. Problem simplification and model description.

[0049] This embodiment focuses on the study of deeply buried circular tunnels. (Reference) Figure 1 The problem is simplified to be located in a hydrostatic pressure field (lateral pressure coefficient). =1) is a two-dimensional plane strain model. The radius of the circular tunnel is After excavation, the surrounding rock underwent plastic deformation, and the radius of its plastic zone was... .

[0050] 2. Premise assumptions.

[0051] To ensure the rigor and computational feasibility of the theoretical model, this embodiment adopts the following basic assumptions:

[0052] (1) The mechanical analysis problem of the circular tunnel-grouting body-surrounding rock-support structure is simplified into a plane strain problem;

[0053] (2) The tunnel is buried at a large depth. Within the tunnel's dimensions, the pressure of the surrounding rock does not change with the height and width, and the weight of the surrounding rock and the grouting body within the calculation range is not considered.

[0054] (3) The surrounding rock and grouting material are ideally elastic-plastic and both conform to the Drucker-Prager yield criterion;

[0055] (4) The grouting fluid injected into the grouting anchor can ensure that the grouting body is sealed in a ring around the tunnel.

[0056] 3. Selection of mechanical parameters of surrounding rock and grouting body.

[0057] (1) Mechanical parameters of surrounding rock.

[0058] Class V surrounding rock was selected as the research object, and its mechanical properties are as follows:

[0059] elastic modulus =1.0 GPa, Poisson's ratio =0.4, internal friction angle =20°, cohesion =0.1MPa.

[0060] (2) Mechanical parameters of the grouting body.

[0061] The mechanical properties of the grouting body are selected as follows:

[0062] elastic modulus =1.5GPa, Poisson's ratio =0.3, internal friction angle =25°, cohesion =0.15MPa.

[0063] (3) Other calculation parameters.

[0064] Surrounding rock pressure =500kPa, tunnel radius taken as =3m, under the shape of the annular grouting body, the anchor bolt length is taken as 6m, and the elastic modulus of the support structure is taken as C25 concrete. =28 GPa, Poisson's ratio =0.25.

[0065] 4. Establishment of the finite element model.

[0066] (1) Calculation scheme.

[0067] refer to Figure 2 Consider 10 different cross-sectional shapes of the grouting body. In the diagram, the thick solid line represents the outer contour of the grouting body, and the dashed line represents the outer contour of the circular tunnel. , , The meaning of the parameters can be directly read from the graph, where, The width of the grouting body is half its width. The radius of the tunnel excavation. This is an intermediate amount when the cross-sectional area of ​​the grouting body is equal, and has no practical significance. For a fair comparison, it is assumed that the same grouting volume is used under 10 working conditions, i.e., the cross-sectional area is equal. For each working condition, the distribution of the plastic zone and stress concentration around the circular tunnel are calculated, and the influence of the lateral pressure coefficient is considered. The lateral pressure coefficient is set accordingly. Calculate using 1.0, 0.75, and 0.5.

[0068] The formulas for calculating the cross-sectional area of ​​10 types of grouting bodies are shown in the table.

[0069] Table 1. Description of Grout Body Shape and Cross-sectional Area Formula

[0070]

[0071] (2) Geometric model establishment.

[0072] Establish Figure 3 The numerical model is shown. In the numerical simulation calculation, the Drucker-Prager yield criterion was selected as the constitutive model to calculate the parameters such as the plastic zone around the tunnel, the stress around the tunnel, and the stress of the support structure (lining) under the action of surrounding rock pressure for the above 10 working conditions. The surrounding rock and the grouting body were simulated using PLANE42 elements, and the element option was set to plane strain (KEYOPT(3)=2); the support structure was simulated using beam elements BEAM188. The model size is 200m (length). 200m (width).

[0073] (3) Boundary condition settings.

[0074] refer to Figure 4 Set boundary conditions. The model is located in the XY plane. Apply load boundary conditions to the four boundaries of the model. The load type is uniformly distributed load, and the vertical load boundary condition is... The lateral load boundary condition is To prevent rigid body displacement in the model, the X-direction displacement at the vertical centerline of the model is constrained, and the Y-direction displacement at the two ends of the horizontal centerline is also constrained. Furthermore, since the BEAM188 element is a three-dimensional beam element, its Z-direction displacement needs to be constrained to avoid displacement perpendicular to the XY plane.

[0075] (4) The influence of mesh size on calculation results.

[0076] Considering the mechanical problems of a deep-buried circular tunnel without grouting reinforcement, under the premise that the surrounding rock and strata both meet the DP yield criterion, the stress distribution around the circular tunnel has an analytical solution, which can be obtained by the following formula:

[0077] ;

[0078] in, , These are the radial and circumferential stresses in the plastic region, respectively. , , To calculate the distance from the point to the center of the circular tunnel, The radius of the circular tunnel is... , , , These are the cohesion of the surrounding rock and the angle of internal friction, respectively. This refers to the stress lode parameter.

[0079] Using the finite element model of working condition 1, considering different mesh sizes, the circumferential stress distribution around a circular tunnel without grouting reinforcement was calculated. The circumferential stress at the top nodes of the tunnel was extracted and compared with the analytical solution. The calculation results are shown in Table 2. The trend of the circumferential stress at the nodes with the mesh size is as follows: Figure 5 As shown.

[0080] Table 2 Comparison of numerical simulation results and analytical solutions for circumferential stress in circular tunnels

[0081]

[0082] From Table 2 and Figure 5 It is evident that the mesh size significantly affects the calculation results of the stress in the plastic zone. When the mesh size is large (0.24m), the numerical simulation of the circumferential stress at the tunnel top has an error of up to 40% compared to the analytical solution. To balance computational accuracy and efficiency, the mesh size with an error of 10% between the theoretical and numerical solutions was ultimately selected for subsequent calculations.

[0083] 5. Calculation results and analysis.

[0084] The calculation results for all working conditions are summarized in Table 3. Working condition 1 (circular grouting body section) is used as the control group.

[0085] Table 3 Summary of Calculation Results

[0086]

[0087] Analysis of the data in Table 3 shows that: when using irregularly shaped grout to reinforce the surrounding rock, both the tunnel clearance convergence and horizontal convergence are reduced to a certain extent; when the lateral pressure coefficient is 1 and 0.75, the shape of the grout has no significant effect on the distribution of the plastic zone of the surrounding rock and the stress of the support structure; however, when the lateral pressure coefficient is 0.5, the shape of the grout has a significant effect on the distribution of the plastic zone of the surrounding rock and the stress of the support structure.

[0088] 6. Optimal selection of grouting body cross section.

[0089] Considering the lateral pressure coefficient When the coefficient of performance (COP) is 0.5, irregularly shaped grouting anchor bolts are used to support the circular tunnel. The radius of the plastic zone of the surrounding rock, the tunnel convergence deformation, and the stress of the support structure obtained from numerical simulation are used as evaluation indicators, with reference to... Figure 6 The hierarchical structure shown employs the Analytic Hierarchy Process (AHP) to optimize the cross-sectional shape of the grouting body. The standard layer includes five indicators: radius of the surrounding rock plastic zone, tunnel clearance convergence displacement, tunnel horizontal convergence displacement, maximum stress of the support structure, and minimum stress of the support structure. The scheme layer comprises nine different grouting body cross-sectional shapes, from working condition 2 to working condition 10.

[0090] Based on the numerical simulation results, a judgment matrix is ​​constructed between the scheme layer and the criterion layer; based on the expert scoring results, a judgment matrix is ​​constructed between the criterion layer and the target layer. The total weight index for each working condition is shown in Table 4.

[0091] Table 4 Total Weighting Indicators

[0092]

[0093] As shown in Table 4, under working condition 10 (oval grouting body cross section), the lateral pressure coefficient... When the coefficient of performance (COP) is 0.5, the total weight index is the highest (0.168), indicating that it has the best comprehensive mechanical properties. Therefore, in this embodiment, the oval grouting body section of working condition 10 is selected for subsequent support system design and construction.

[0094] 7. Grouting anchor construction.

[0095] Reference Figure 7 Grouting anchor bolts are arranged. To form the preferred oval grout body cross-section, the impact of grout diffusion on the grouting reinforcement effect must be fully considered. Among them, the anchor bolt spacing, grouting pressure, and grouting retention time are the main factors affecting grout diffusion. The specific construction parameters in this embodiment are as follows:

[0096] Anchor spacing: 1.04m, grouting pressure: 3MPa, grouting holding time: 500s.

[0097] This embodiment verifies the superiority of the oval cross section under specific geological conditions through complete numerical simulation and optimization analysis, providing theoretical basis and practical guidance for the engineering application of irregular grouting anchor support system.

[0098] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0099] Therefore, the present invention adopts the above-mentioned irregular grouting anchor support system and selection and construction method. By establishing a mechanical model, conducting numerical simulation and multi-index decision analysis, the scientific optimization and construction of the grouting body cross-sectional shape are realized, thereby achieving the purpose of improving the stress state of the surrounding rock, controlling deformation and improving the support effect.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A selection and construction method for an irregular grouting anchor support system, characterized in that, Includes the following steps: Step S1: Obtain the physical and mechanical parameters of the surrounding rock, grouting body, and support structure within the current tunnel construction area; Step S2: Based on the acquired physical and mechanical parameters, establish a plane strain mechanical analysis model of the tunnel-grouting body-surrounding rock-support structure; Step S3: Based on the established plane strain mechanical analysis model of tunnel-grouting body-surrounding rock-support structure, establish a finite element numerical simulation calculation model to calculate the mechanical response of various preset irregular grouting body sections under the action of surrounding rock pressure under the same grouting volume conditions. Step S4: Using mechanical response data as the judgment index, a multi-index decision analysis method is adopted to comprehensively evaluate different irregular grouting body cross-sectional forms, and select the optimal grouting body cross-sectional form accordingly. Step S5: Based on the optimal grouting body cross-sectional shape, determine the arrangement parameters of the grouting anchors and the grouting parameters, and carry out construction to form a closed irregular grouting body in the surrounding rock of the tunnel. Step S2, the process of establishing the plane strain mechanical analysis model of the tunnel-grouting body-surrounding rock-support structure includes the following steps: Step S21: Simplify the three-dimensional tunnel construction problem into a plane strain problem; Step S22: Set the surrounding rock pressure acting on the model as a uniformly distributed load that does not change with the tunnel size, and ignore the self-weight of the surrounding rock and the grouting body; Step S23: Define the surrounding rock and grout material as ideal elastic-plastic materials, and use the Drucker-Prager yield criterion as its plastic yield condition; Step S24: Assume that the grouting anchors are densely distributed to ensure that the grouting body formed is closed in a ring around the tunnel.

2. The selection and construction method of the irregular grouting anchor support system according to claim 1, characterized in that, In step S1, the physical and mechanical parameters of the surrounding rock include elastic modulus, Poisson's ratio, internal friction angle, cohesion, surrounding rock pressure, and surrounding rock lateral pressure coefficient; the physical and mechanical parameters of the grouting body include elastic modulus, Poisson's ratio, internal friction angle, and cohesion; and the physical and mechanical parameters of the support structure include elastic modulus and Poisson's ratio.

3. The selection and construction method of the irregular grouting anchor support system according to claim 1, characterized in that, In step S3, the various preset irregular grout body cross sections include annular, short teardrop, tall teardrop, short spindle, long spindle, triangle, umbrella, roly-poly, and oval.

4. The selection and construction method of the irregular grouting anchor support system according to claim 1, characterized in that, In step S3, the mechanical response includes the range of the plastic zone around the tunnel, the tunnel convergence deformation, and the stress of the support structure.

5. The selection and construction method of the irregular grouting anchor support system according to claim 1, characterized in that, Step S3, the process of establishing the finite element numerical simulation calculation model includes the following steps: Step S31: Use PLANE42 elements to simulate the surrounding rock and grouting body, and set its element option to plane strain; at the same time, use BEAM188 elements to simulate the support structure. Step S32: Apply a uniformly distributed load corresponding to the surrounding rock pressure and lateral pressure coefficient to the model boundary, and constrain the normal displacement of the model centerline to avoid rigid body displacement.

6. The selection and construction method of the irregular grouting anchor support system according to claim 1, characterized in that, In step S4, the multi-index decision analysis method is the Analytic Hierarchy Process (AHP), which includes the following steps: Step S41: Select the optimal grouting body cross section as the target layer, the mechanical response index as the criterion layer, and the cross section form of each grouting body as the scheme layer. Step S42: Based on the numerical simulation results of step S3, construct the judgment matrix of the scheme layer relative to the criterion layer; Step S43: Based on expert scoring, construct the judgment matrix of the criterion layer relative to the target layer; Step S44: Calculate the eigenvectors of each of the above judgment matrices and perform a consistency check; Step S45: Based on the feature vectors calculated in step S44, calculate the total weight of each grouting body cross-section in the scheme layer relative to the target layer, and use this as a comprehensive evaluation index to select the cross-section with the highest total weight as the optimal scheme.

7. The selection and construction method of an irregular grouting anchor support system according to claim 6, characterized in that, In step S4, when the lateral pressure coefficient of the surrounding rock is less than or equal to 0.5, the optimal grouting body cross-section shape selected by the multi-index decision analysis method is oval.

8. The selection and construction method of the irregular grouting anchor support system according to claim 1, characterized in that, In step S5, the arrangement parameters of the grouting anchor bolts include the anchor bolt length and the spacing between the anchor bolts; the grouting parameters include the grouting pressure and the grouting holding time.

9. A non-circular grouting anchor support system designed and constructed using the method described in any one of claims 1-8, characterized in that, The grouting body formed by the support system in the surrounding rock of the tunnel has a non-circular irregular cross-sectional shape.

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