System and method for optimizing full-section construction circulating footage of long tunnel

Abstract

The invention relates to the technical field of tunnel engineering construction, in particular to a long tunnel full-section construction circulating footage optimization system and method. Aiming at the problems of inaccurate support force calculation and lack of a comprehensive evaluation system in the prior art, the method comprises the following steps of: setting multi-grade circulating footage in a test section, calculating average time consumption per linear meter and single-cycle error time under each grade, and counting the optimal candidate footage of the whole construction period according to the calculated time consumption and single-cycle error time; establishing a tunnel face stability failure model, and determining the maximum load of the surrounding rock of the tunnel face; a logarithmic spiral failure model of the tunnel face is established, and the corresponding relation between the multi-gear circulating footage and the supporting force is obtained; establishing a cyclic footage evaluation index according to the construction period and the supporting force of the multi-gear cyclic footage, calculating a comprehensive score of different cyclic footage according to the cyclic footage evaluation index, and screening an optimal footage; and rechecking the optimal footage by taking the construction aging average value of the optimal candidate footage of the test section and the maximum load of the surrounding rock of the tunnel face as comprehensive evaluation indexes.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering construction technology, specifically to an optimized system and method for cyclic advance during full-section construction of long tunnels. Background Technology

[0002] In the field of tunnel construction technology, especially for the construction of long tunnels under weak surrounding rock conditions, existing construction methods face numerous challenges. Weak surrounding rock (such as Class IV and V surrounding rock) is prone to safety hazards such as rockfall and excessive deformation during excavation, leading to construction delays, increased costs, and potential safety risks. These problems not only affect project efficiency but may also cause structural instability, increasing the burden of subsequent support and repair. With the rapid development of infrastructure construction, long tunnel projects are increasing, and the demand for advanced construction technologies is becoming increasingly urgent. While traditional construction methods ensure the stability of the surrounding rock to a certain extent, they often sacrifice mechanization efficiency and cannot meet the requirements of modern engineering for speed and cost control.

[0003] According to the "Technical Specification for Highway Tunnel Construction" (JTG / T 3660-2020), the bench method should be used for Class IV and V surrounding rock. This method controls the stability of the surrounding rock through layered excavation. For example, the upper bench is excavated first, and then the excavation gradually extends downwards to reduce the area excavated at one time, thereby reducing the risk of deformation caused by stress release in the surrounding rock. The bench method has been widely used in practice and has proven its effectiveness in maintaining the stability of the surrounding rock in many tunnel projects. However, this method has significant limitations: the bench method makes it difficult to fully utilize the efficiency of large-scale machinery, resulting in a longer construction period, low machinery utilization, and an inability to meet the demands of modern tunnel engineering for rapid mechanized construction. Specifically, under the bench method, machinery such as rock drilling rigs and shotcrete machines cannot operate continuously and require frequent adjustments to their positions and changes in procedures. This not only increases manual intervention but also increases equipment idle time. According to relevant engineering statistics, when using the bench method in tunnels with weak surrounding rock, the average daily progress is often less than 2 meters, while full-section mechanized construction can theoretically achieve more than 3-5 meters. This gap directly leads to delays in the construction period and cost overruns.

[0004] Existing research primarily focuses on optimizing blasting effects and analyzing surrounding rock pressure distribution. These studies provide a valuable theoretical foundation for tunnel construction and can, to some extent, provide early warnings of collapse risks. However, these studies are often limited to optimizing local factors and lack a systematic approach for the full-section mechanized construction of long tunnels in weak surrounding rock. Specifically, they suffer from the following shortcomings:

[0005] Disadvantage 1: Existing tunnel construction technologies still face bottlenecks in promoting the application of full-face mechanized excavation under weak surrounding rock conditions. Although traditional blasting or mechanical tunneling methods can achieve full-face excavation, they are prone to causing face instability in weak surrounding rock. For example, in deeply buried tunnels, the self-weight of the surrounding rock and lateral pressure may cause the excavation face to collapse rapidly. Existing support measures such as anchor bolts and shotcrete can provide immediate support, but the calculation of support force is often based on simplified models, such as the classic Janssen silo theory. This theory assumes that the face boundary is rectangular and ignores the stress gradient changes at the tunnel edge, resulting in a large deviation in the estimation of support force.

[0006] Disadvantage 2: Existing technologies also suffer from strong subjectivity in advance selection and a lack of objective evaluation indicators. While many studies have conducted surrounding rock mechanics simulations, they haven't incorporated actual construction period data, leading to optimized solutions that are detached from engineering practice. Related literature shows that in long tunnel projects, due to the lack of a comprehensive evaluation system, construction teams often face the dilemma of either insufficient advance leading to low efficiency or excessive advance causing safety accidents. This not only increases engineering risks but also hinders the promotion of mechanized technologies.

[0007] Furthermore, traditional methods often rely on single indicators, such as the deformation rate of the surrounding rock or the blasting vibration velocity, while neglecting comprehensive evaluation of multiple factors. This is particularly prominent in long tunnels, where geological conditions often vary significantly when the tunnel length exceeds 5 kilometers, making it difficult to address the needs of the entire tunnel with a single optimization approach. Although relevant specifications stipulate the classification of surrounding rock and construction principles, they do not provide quantitative tools to balance construction period and safety, resulting in a high degree of subjectivity in the selection of tunnel advance and susceptibility to human factors. Summary of the Invention

[0008] In view of the shortcomings pointed out in the background art above, this application proposes the following solutions:

[0009] Solution 1:

[0010] Regarding the issues mentioned in Disadvantage 1, such as the tendency of full-face mechanized excavation to cause face instability under weak surrounding rock conditions and the insufficient accuracy of the support force calculation model, this invention improves the Janssen silo theory model by modifying the face boundary from a rectangle to an inverted trapezoid, establishing a face stability failure model affected by excavation cycle advance. This model consists of an upper square and a lower logarithmic spiral. Limit equilibrium analysis is used to solve for the maximum vertical force on the logarithmic spiral, and the surrounding rock parameters c are substituted based on field geological data. The value is used to obtain the precise correspondence between the cyclic advance and the support force, thereby dynamically adjusting the advance to balance the stability of the surrounding rock, avoiding deviations in the support force estimation, and achieving safe and efficient full-face excavation.

[0011] Solution 2:

[0012] Regarding the lack of comprehensive evaluation indicators mentioned in Disadvantage 2, this invention integrates statistical data on construction period with theoretical analysis of support force to establish comprehensive evaluation indicators. Specifically, the construction period indicator is calculated by collecting average time per meter and single-cycle delay data under different cyclic advances in the test section. Combined with the support force indicator obtained from theoretical analysis, weights are calculated according to data standardization, information entropy, and difference coefficient. Different advance schemes are evaluated using a comprehensive scoring formula, thereby solving the problem of balancing construction period and safety, avoiding the risk of subjective selection, and improving the overall optimization effect of mechanized construction.

[0013] Based on the above technical concept, the technical solution adopted by this invention is as follows:

[0014] One object of the present invention is to provide an optimized method for cyclic advance during full-section construction of long tunnels, characterized by comprising the following steps:

[0015] In the test section, multiple cyclic advances were set up, and the average time per meter and single cycle delay were calculated for each advance. Based on this, the optimal candidate advance for the entire project period was statistically analyzed.

[0016] Establish a failure model for the tunnel face stability and determine the maximum load on the surrounding rock at the tunnel face;

[0017] A logarithmic spiral failure model of the tunnel face was established to obtain the correspondence between multiple cyclic advances and support forces.

[0018] Based on the construction period and support force of multiple cyclic advances, establish cyclic advance evaluation indexes, calculate the comprehensive score of different cyclic advances based on the cyclic advance evaluation indexes, and select the optimal advance.

[0019] The optimal advance was verified by using the average construction time of the optimal candidate advance in the test section and the maximum load of the surrounding rock at the tunnel face as comprehensive evaluation indicators.

[0020] Further defining the above technical solution, the candidate advance with the optimal construction period is selected by statistically analyzing the average time per meter and the single-cycle delay of advances in multiple cycles, and then selecting the advance with the minimum time per meter and the single-cycle delay.

[0021] Further defining the above technical solution, the multiple cyclic advances are 1m, 2m, 3m, and 4m, with the optimal candidate advance for the construction period being 3 meters.

[0022] Further defining the above technical solution, the tunnel face stability failure model consists of an upper rectangular body and a lower logarithmic spiral. When the lower logarithmic spiral can balance the vertical pressure from above, the tunnel face is in a stable state; otherwise, the tunnel face will experience instability and failure. The vertical force acting on the coupling interface EF between the upper rectangular body and the lower logarithmic spiral is:

[0023]

[0024] In the formula, F v R represents the vertical force, H represents the tunnel radius, γ represents the tunnel depth, γ represents the unit weight of the surrounding rock, λ represents the coefficient of lateral pressure of the surrounding rock, and c and Representing the cohesion and internal friction angle of the surrounding rock respectively, r0 represents the helix radius, σ s This indicates additional loads on the ground surface.

[0025] Further defining the above technical solution, the logarithmic spiral failure model of the tunnel face corresponds to and characterizes the force and failure mechanism of the lower logarithmic spiral in the tunnel face stability failure model, and its configuration is as follows:

[0026] With the center of the logarithmic spiral as the origin O of the rectangular coordinate system, the initial angle EOG is θα = arctan(D / 2l);

[0027] Where D is the tunnel excavation height, h = D; l is the cycle advance, θ α The angle between the hypotenuse of the irregular wedge and the horizontal plane.

[0028] Further defining the above technical solution, based on the logarithmic spiral failure model of the tunnel face, the maximum vertical force F on the EF surface is obtained under the limit equilibrium condition, and the corresponding relationship between the cyclic advance and the support force is obtained accordingly.

[0029] Further defining the above technical solution, the solution for the maximum vertical force F on the EF surface includes the following steps:

[0030]

[0031] In the formula:

[0032]

[0033] In the formula, k1~k4 represent function coefficients, F represents the maximum vertical force, θ is the angle between the hypotenuse of the irregular wedge and the horizontal plane, and c and Let r0 represent the cohesion and internal friction angle of the surrounding rock, r0 represent the helix radius, γ represent the unit weight of the surrounding rock, λ represent the lateral pressure coefficient of the surrounding rock, and σ represent the normal stress.

[0034] Substituting the surrounding rock parameters c obtained from the field geological survey data, The value is used to obtain the relationship between the cyclic advance and the support force, where the support force increases with the increase of the excavation advance, but the rate of increase decreases with the increase of the advance.

[0035] To further define the above technical solutions, a comprehensive evaluation system is constructed through the following steps:

[0036] Based on the project duration index T(l) and support force index F(l) under different cycle advances l, data standardization processing is performed;

[0037] Calculate the standardized information entropy and difference coefficient to determine the work option weight ω. 工期 and support force weight ω 支护力 ;

[0038] Construct the comprehensive score S(l) for cyclic advance;

[0039]

[0040] Among them, T max and F max These represent the construction period and the maximum support force, respectively. 工期 For the sake of work options, ω 支护力 As the weight of the support force;

[0041] The cyclic advance with the smallest comprehensive score S(l) is selected as the optimal advance.

[0042] Another object of the present invention is to provide an optimized cyclic advance system for full-section construction of long tunnels to achieve the method described in any one of the above, comprising:

[0043] The optimal candidate advance measurement determination module is used to set multiple cyclic advance measurement levels in the experimental section, record the average time per meter under each level, the single cycle delay, and output the optimal candidate advance measurement for the project period.

[0044] The tunnel face stability failure module is used to calculate the vertical force and determine the maximum load on the surrounding rock of the tunnel face based on the tunnel face stability failure model.

[0045] The logarithmic spiral failure module is used to establish a logarithmic spiral failure model of the working face and output the correspondence between multiple cyclic advances and the required support force.

[0046] The comprehensive evaluation module is used to establish evaluation indicators for cyclic advance based on the construction period and support force of multiple cyclic advances, calculate the comprehensive score of each advance, and select the optimal advance.

[0047] The verification module is used to verify the optimal advance based on the average construction time of the optimal candidate advance in the test section and the maximum load of the surrounding rock at the working face, and output the verification conclusion.

[0048] Compared with existing technologies, the improved Janssen silo theory model and comprehensive evaluation index of this invention bring the following significant effects:

[0049] 1. This invention significantly improves the calculation accuracy of the support force at the face of long tunnels under weak surrounding rock conditions and enhances the ability to control the stability of the surrounding rock by improving the silo model. The invention modifies the boundary to an inverted trapezoid, constructing a stability failure model with an upper square body and a lower logarithmic spiral body. Limit equilibrium analysis is used to solve for the vertical force F, and on-site surrounding rock parameters (unit weight γ, lateral pressure coefficient λ, cohesion c, internal friction angle) are substituted. (etc.) This yielded a nonlinear relationship where the support force increases with increasing advance length l, but at a decreasing rate. This improvement considers the influence of burial depth H on the vertical force, avoids errors in simplified models, and improves the accuracy of support force prediction. Simultaneously, the model's rationality was verified through field monitoring data, effectively reducing the risk of collapse in practical applications. In the application at the Qilin Guan Tunnel on the Hubei-Hunan border section of the Hubei-Hunan Expressway, the model showed minimal discrepancies with field monitoring data, demonstrating reasonable theoretical calculations and feasible methods.

[0050] 2. This invention effectively achieves a dynamic balance between schedule optimization and support force control, improving the overall decision-making efficiency of full-section mechanized construction of long tunnels. Existing technologies lack a systematic evaluation framework, and the disconnect between schedule data statistics and surrounding rock mechanics analysis leads to strong subjectivity in advance selection, often presenting construction teams with the dilemma of low efficiency or safety hazards. This invention establishes a comprehensive evaluation index system, integrating average time per meter under different advances in the test section and single-cycle delay data to calculate the schedule index T(l), combined with the theoretical support force F(l), and calculating weights through data standardization, information entropy, and difference coefficients. The scoring formula S(l) is used to quantitatively evaluate multiple schemes, recommending an optimal advance of 3 meters. This system considers multiple factors, avoiding the limitations of a single index, and making the optimized scheme more aligned with engineering practice. In the Qilin Guan Tunnel application, this method stabilized the daily advance at over 3 meters, shortened the construction period by 61 days, significantly improved the continuous operation rate of mechanical equipment, and significantly reduced resource waste and schedule delay risks. This effect not only solves the problem of data disconnect, but also provides a replicable quantitative tool for similar projects, promoting the sustainable development of tunnel engineering. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] Figure 1 This is a stability analysis model for the tunnel face.

[0053] Figure 2 This is a model for the instability and failure of the surrounding rock near the working face.

[0054] Figure 3 This is a model for the instability and failure of a logarithmic spiral and an analysis of the stress on a single element.

[0055] Figure 4 This relates to the relationship between support force and cyclic advance. Detailed Implementation

[0056] This application proposes a system and method for optimizing cyclic advance during full-face construction of long tunnels, primarily addressing the challenge of balancing construction efficiency and rock stability in soft surrounding rock conditions. This application provides an effective and innovative method that optimizes cyclic advance by integrating statistical data on construction period, theoretical optimization of support force, and a comprehensive evaluation index system. Specifically, the method first analyzes the impact of different advances on the construction period based on experimental section data, obtaining the optimal candidate advance for optimal efficiency. Second, it improves the Janssen silo theory model, establishing a logarithmic spiral failure model of the tunnel face considering cyclic advance, theoretically solving for the support force requirement. Finally, it constructs a multi-index comprehensive evaluation system, quantifying the weights of construction period and support force, and calculating a comprehensive score to determine the optimal advance. This approach balances engineering practice and mechanical theory, ensuring safe and efficient full-face mechanized construction in Class IV and Class V surrounding rock.

[0057] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0058] Example 1

[0059] A cyclic advance optimization method integrating schedule optimization and support force control is proposed, comprising the following steps:

[0060] Step 1: Statistics on the relationship between construction period and progress

[0061] Based on the influence of different advances on the average time per meter in the test section, the optimal cyclic advance for controlling the construction period was obtained.

[0062] The time taken and time lost for each process were collected and statistically analyzed under different cycle advances (1m, 2m, 3m, 4m) in the test section (Qilinguan Tunnel YK8+100 to YK8+400). The results are shown in Table 1.

[0063] Table 1. Statistics of Single Cycle Operation Time at the Tunnel Face

[0064]

[0065] Table 1 shows that the construction efficiency is highest when the cycle advance is 3 meters, with the lowest time per linear meter (6.50 hours) and the lowest single-cycle delay (2.30 hours). A 3-meter advance balances workload and time, optimizing the construction process and equipment utilization. Beyond 3 meters, construction complexity increases, and delays rise.

[0066] Step 2: Optimization of Support Force-Advance Theory

[0067] The relationship between cyclic advance and support force was derived using an improved Janssen silo theory, and the rationality of the theoretical analysis was verified using field monitoring data.

[0068] The theoretical model of the silo was optimized by changing the boundary of the working face from a rectangle to an inverted trapezoid. Figure 1 This allows for a more accurate description of the stress changes and mechanical behavior of the surrounding rock at the tunnel edge. Figure 1 In the diagram, G represents the horizontal frictional force acting on the irregular wedge-shaped solid, V represents the vertical force, and σ represents the vertical force. n θ represents the horizontally distributed support force at the working face, and θ is the angle between the hypotenuse of the irregular wedge and the horizontal plane.

[0069] Given a tunnel excavation height of D, a width of B, an excavation depth of h, a burial depth of H, and a cycle advance of l, a failure model of the tunnel face stability affected by the excavation cycle advance was established. Figure 2 The model consists of an upper rectangular prism and a lower (EFG) logarithmic spiral, with shear strength acting around the perimeter of both the rectangular prism and the logarithmic spiral. The tunnel face is stable when the lower logarithmic spiral can balance the vertical pressure from above; otherwise, the tunnel face will buckle and fail. The vertical force acting on EF is calculated as follows:

[0070]

[0071] In the formula, F v R represents the vertical force, H represents the tunnel radius, γ represents the tunnel depth, γ represents the unit weight of the surrounding rock, λ represents the coefficient of lateral pressure of the surrounding rock, and c and Representing the cohesion and internal friction angle of the surrounding rock respectively, r0 represents the helix radius, σ s This indicates additional loads on the ground surface.

[0072] As can be seen from equation (1), the vertical force generated by the square body is positively correlated with the tunnel burial depth H. When the tunnel burial depth H increases to a certain extent, the influence of the burial depth increment on the vertical force is negligible, and the vertical force will be a constant value. The above equation can be used to determine the maximum load acting on the surrounding rock of the tunnel face.

[0073] Based on the Lee model test results and silo theory, a logarithmic spiral failure model for the tunnel face considering the influence of cyclic advance was established. Figure 3The logarithmic spiral failure model of the tunnel face corresponds to and characterizes the force and failure mechanism of the lower logarithmic spiral in the tunnel face stability failure model. The center of the logarithmic spiral in this model is the origin O of the rectangular coordinate system, and the initial ∠EOG is θ. α =arctan(D / 2l) (D is the tunnel excavation height, h = D; l is the cycle advance, θ) α (The angle between the hypotenuse of the irregular wedge and the horizontal plane).

[0074] Based on limit equilibrium analysis, the maximum vertical force F on the EF surface of the logarithmic spiral is determined.

[0075]

[0076] In the formula:

[0077]

[0078] In the formula, k1~k4 represent function coefficients, F represents the maximum vertical force, θ is the angle between the hypotenuse of the irregular wedge and the horizontal plane, and c and Let r0 represent the cohesion and internal friction angle of the surrounding rock, r0 represent the helix radius, γ represent the unit weight of the surrounding rock, λ represent the lateral pressure coefficient of the surrounding rock, and σ represent the normal stress.

[0079] c, obtained from on-site geological survey data Substituting the value into equation (2) yields Figure 4 The relationship between the cyclic advance and the support force shown is derived from... Figure 4 It can be seen that the support force required for the stability of the free face of the arch increases with the increase of the excavation depth, but the rate of increase decreases with the increase of the depth.

[0080] Step 3: Comprehensive Evaluation Index System

[0081] By combining the construction period and support strength, an evaluation system index is established to obtain the optimal cyclic advance.

[0082] The project duration index was calculated based on the time per meter under different cyclic advances obtained from field tests, and the support force index was obtained based on theoretical analysis under different cyclic advances. The weights of project duration and support force were determined by following the order of data standardization → calculating the proportion matrix → calculating information entropy → calculating the difference coefficient. The standardized values, information entropy, difference coefficient, and weights used in the calculation process are shown in Table 2.

[0083] Table 2 Evaluation Indicators for Different Cycle Advances

[0084]

[0085] The score for different cyclic advances l is calculated using equation (3).

[0086]

[0087] In the formula, S(l) is the comprehensive score under cyclic advance l, T(l) and F(l) represent the construction period and support force under cyclic advance l, respectively, and T max and F max These represent the construction period and the maximum support force, respectively. 工期 For the sake of work options, ω 支护力 The support force weight.

[0088] Table 3 is obtained by comparing the comprehensive scores of the four cyclic advances obtained by equation (3). As can be seen from Table 3, the comprehensive score is the lowest when the cyclic advance is 3m, and the smallest difference between the scores is 0.67. Therefore, considering the construction period and support force, it is recommended that the cyclic advance be 3m.

[0089] Table 3. Overall Score for Different Cycle Advances

[0090] Cyclic advance (m) 1 2 3 4 Overall score 0.76 0.81 0.09 1.00

[0091] Example 2

[0092] In this embodiment, a cyclic advance optimization system for full-section construction of long tunnels was built to achieve the goal of optimizing the cyclic advance of full-section mechanized construction of long tunnels under weak surrounding rock conditions.

[0093] The optimization system includes:

[0094] The optimal candidate advance measurement determination module is used to set multiple cyclic advance measurement levels in the experimental section, record the average time per meter under each level, the single cycle delay, and output the optimal candidate advance measurement for the project period.

[0095] The tunnel face stability failure module is used to calculate the vertical force and determine the maximum load on the surrounding rock of the tunnel face based on the tunnel face stability failure model.

[0096] The logarithmic spiral failure module is used to establish a logarithmic spiral failure model of the working face and output the correspondence between multiple cyclic advances and the required support force.

[0097] The comprehensive evaluation module is used to establish evaluation indicators for cyclic advance based on the construction period and support force of multiple cyclic advances, calculate the comprehensive score of each advance, and select the optimal advance.

[0098] The verification module is used to verify the optimal advance based on the average construction time of the optimal candidate advance in the test section and the maximum load of the surrounding rock at the working face, and output the verification conclusion.

[0099] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention, enabling those skilled in the art to understand and apply it. However, it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to the present invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention.

Claims

1. A method for optimizing cyclic advance during full-section construction of long tunnels, characterized in that, Includes the following steps: In the test section, multiple cyclic advances were set up, and the average time per meter and single cycle delay were calculated for each advance. Based on this, the optimal candidate advance for the entire project period was statistically analyzed. Establish a failure model for the tunnel face stability and determine the maximum load on the surrounding rock at the tunnel face; A logarithmic spiral failure model of the tunnel face was established to obtain the correspondence between multiple cyclic advances and support forces. Based on the construction period and support force of multiple cyclic advances, establish cyclic advance evaluation indexes, calculate the comprehensive score of different cyclic advances based on the cyclic advance evaluation indexes, and select the optimal advance. The optimal advance was verified by using the average construction time of the optimal candidate advance in the test section and the maximum load of the surrounding rock at the tunnel face as comprehensive evaluation indicators.

2. The method for optimizing cyclic advance during full-section construction of long tunnels according to claim 1, characterized in that, The optimal candidate advance is selected by statistically analyzing the average time per meter and the single-cycle delay of multiple advance cycles, and then selecting the advance with the smallest average time per meter and single-cycle delay.

3. The method for optimizing cyclic advance during full-section construction of long tunnels according to claim 2, characterized in that, The multi-stage cyclic advance is divided into 1m, 2m, 3m and 4m, with the optimal candidate advance for the project period being 3m.

4. The method for optimizing cyclic advance during full-section construction of long tunnels according to claim 1, characterized in that, The tunnel face stability failure model consists of an upper rectangular block and a lower logarithmic spiral. The tunnel face is stable when the lower logarithmic spiral can balance the vertical pressure from above; otherwise, the tunnel face fails due to instability. The vertical force acting on the coupling interface EF between the upper rectangular block and the lower logarithmic spiral is: In the formula, F v R represents the vertical force, H represents the tunnel radius, γ represents the tunnel depth, γ represents the unit weight of the surrounding rock, λ represents the lateral pressure coefficient of the surrounding rock, and c and Representing the cohesion and internal friction angle of the surrounding rock respectively, r0 represents the helix radius, σ s This indicates additional loads on the ground surface.

5. The method for optimizing cyclic advance during full-section construction of long tunnels according to claim 1, characterized in that, The logarithmic spiral failure model of the tunnel face corresponds to and characterizes the force and failure mechanism of the lower logarithmic spiral in the tunnel face stability failure model. Its configuration is as follows: With the center of the logarithmic spiral as the origin O of the rectangular coordinate system, and the initial angle EOG as θ α =arctan(D / 2l); Where D is the tunnel excavation height, h = D; l is the cycle advance, θ α The angle between the hypotenuse of the irregular wedge and the horizontal plane.

6. The method for optimizing cyclic advance during full-section construction of long tunnels according to claim 5, characterized in that, Based on the logarithmic spiral failure model of the tunnel face, the maximum vertical force F on the EF face is obtained under the limit equilibrium condition, and the corresponding relationship between the cyclic advance and the support force is obtained accordingly.

7. The method for optimizing cyclic advance during full-section construction of long tunnels according to claim 6, characterized in that, The solution for the maximum vertical force F on the EF plane includes the following steps: In the formula: In the formula, k1~k4 represent function coefficients, F represents the maximum vertical force, θ is the angle between the hypotenuse of the irregular wedge and the horizontal plane, and c and Let r0 represent the cohesion and internal friction angle of the surrounding rock, r0 represent the helix radius, γ represent the unit weight of the surrounding rock, λ represent the lateral pressure coefficient of the surrounding rock, and σ represent the normal stress. Substituting the surrounding rock parameters c obtained from the field geological survey data, The values ​​were used to obtain the correspondence between multiple cyclic advances and support forces. The support force increases with the increase of excavation advance, but the rate of increase decreases with the increase of advance.

8. The method for optimizing cyclic advance during full-section construction of long tunnels according to claim 1, characterized in that, The evaluation index for cyclic advance is constructed through the following steps: Based on the project duration index T(l) and support force index F(l) under different cycle advances l, data standardization processing is performed; Calculate the standardized information entropy and difference coefficient to determine the work option weight ω. 工期 and support force weight ω 支护力 ; Construct the comprehensive score S(l) for cyclic advance; Among them, T max and F max These represent the construction period and the maximum support force, respectively; ω 工期 For the sake of work options, ω 支护力 Weight of support force; The cyclic advance with the smallest comprehensive score S(l) is selected as the optimal advance.

9. A system for optimizing cyclic advance during full-section construction of long tunnels, characterized in that, To implement the method of any one of claims 1-8, the method comprises: The optimal candidate advance measurement determination module is used to set multiple cyclic advance measurement levels in the experimental section, record the average time per meter under each level, the single cycle delay, and output the optimal candidate advance measurement for the project period. The tunnel face stability failure module is used to calculate the vertical force and determine the maximum load on the surrounding rock of the tunnel face based on the tunnel face stability failure model. The logarithmic spiral failure module is used to establish a logarithmic spiral failure model of the working face and output the correspondence between multiple cyclic advances and the required support force. The comprehensive evaluation module is used to establish evaluation indicators for cyclic advance based on the construction period and support force of multiple cyclic advances, calculate the comprehensive score of each advance, and select the optimal advance. The verification module is used to verify the optimal advance based on the average construction time of the optimal candidate advance in the test section and the maximum load of the surrounding rock at the working face, and output the verification conclusion.

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