Active control method for tunnel surrounding rock stability based on space-time effect

Abstract

This invention discloses an active control method for tunnel surrounding rock stability based on spatiotemporal effects, relating to the field of tunnel engineering support design technology. The method includes: dividing the spatiotemporal effects of tunnel surrounding rock stability into unit sections; establishing a mechanical analysis model for surrounding rock stability; calculating the deterioration effect of surrounding rock deformation on surrounding rock mechanical parameters; analyzing the influence of support methods on the regulation of surrounding rock mechanical parameters; determining the stability of unsupported sections and identifying reasonable support timing; and determining the stability of supported sections. This invention employs the aforementioned active control method for tunnel surrounding rock stability based on spatiotemporal effects. Based on the control of surrounding rock stress-strain state, it analyzes the deterioration and regulation effects of construction spatiotemporal effects on surrounding rock mechanical parameters. While effectively ensuring surrounding rock stability, it achieves quantitative calculations of physical and mechanical parameters of surrounding rock under different states, reasonable support timing, and reasonable support system parameters, thereby improving the accuracy and scientific nature of tunnel surrounding rock stability control.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering support design technology, and in particular to an active control method for the stability of tunnel surrounding rock based on spatiotemporal effects. Background Technology

[0002] Rock stability and its control are core elements for ensuring tunnel construction safety and guiding the scientific design of support systems. Influenced by the spatiotemporal effects of excavation and support construction, rock stability exhibits significant dynamic evolution characteristics. In other words, the stability of rock under different conditions changes dynamically. Therefore, analyzing and quantifying rock stability is crucial for its scientific control. Currently, due to a lack of understanding of the evolutionary laws governing rock stability, engineering practice relies heavily on manual experience for control. This leads to significant randomness in the implementation process, posing substantial risks to safe construction. Summary of the Invention

[0003] The purpose of this invention is to provide an active control method for tunnel surrounding rock stability based on spatiotemporal effects, which solves the problem of difficulty in quantifying surrounding rock stability control, improves the accuracy and scientific nature of active control of surrounding rock stability, and advances the level of tunnel surrounding rock stability control technology, and has broad application prospects.

[0004] To achieve the above objectives, this invention provides an active control method for tunnel surrounding rock stability based on spatiotemporal effects, comprising the following steps: S1. Based on the excavation advance length index for each stage, the spatiotemporal effects of the surrounding rock stability of the tunnel are divided into unit sections. S2. Establish a mechanical analysis model for the stability of the surrounding rock; S3. Calculate the effect of surrounding rock deformation on the deterioration of surrounding rock mechanical parameters; S4. Analyze the influence of support methods on the regulation of surrounding rock mechanical parameters; S5. Conduct a stability assessment of the unsupported section of surrounding rock and determine the appropriate timing for support. S6. Determine the stability of the surrounding rock in the support section.

[0005] Preferably, S2 includes: combining the geometric characteristics of the tunnel excavation, dividing the tunnel into multi-centered circular arc segments, taking each arc segment as the basic unit for surrounding rock mechanics analysis, establishing a surrounding rock stability mechanics analysis model, and determining the surrounding rock stability state and surrounding rock stability coefficient in the surrounding rock stability mechanics analysis model.

[0006] Preferably, in step S2, determining the surrounding rock stability state and surrounding rock stability coefficient in the surrounding rock stability mechanical analysis model includes the following steps: S21. Take the thickness of the surrounding rock in the mechanical analysis model of surrounding rock stability as the thickness of the excavation influence range, and calculate the thickness of the excavation influence range. S22. Based on the thickness of the excavation influence range, calculate the external loads acting on the surrounding rock in the mechanical analysis model of surrounding rock stability; S23. Calculate the stress at the bottom of the surrounding rock in the mechanical analysis model of surrounding rock stability based on the external loads acting on the surrounding rock. S24. Calculate the deformation value at the bottom of the surrounding rock in the mechanical analysis model of surrounding rock stability; S25. Determine the stability state of the surrounding rock based on the stress and deformation value at the bottom of the surrounding rock, and calculate the stability coefficient of the surrounding rock.

[0007] Preferably, the stability state of the surrounding rock in S25 is shown in the following formula: ; The surrounding rock stability coefficient is shown in the following formula: ; in, The stress at the bottom of the excavated surrounding rock is expressed in MPa. The ultimate compressive strength of the surrounding rock is expressed in MPa. The value represents the deformation of the surrounding rock during excavation, in meters (m). The ultimate tensile strength of the surrounding rock, in MPa. is the surrounding rock stability coefficient.

[0008] Preferably, S3 includes: S31. The ratio of the deformation value at the bottom of the surrounding rock to the thickness of the excavation influence range is defined as the surrounding rock deformation rate, which is shown in the following formula: ; in, The value is the deformation rate of the surrounding rock, expressed in % (%). The value represents the deformation of the surrounding rock, in meters (m). The thickness of the affected area is expressed in meters (m). S32. The deterioration effect on the mechanical parameters of the surrounding rock is calculated based on the deformation rate of the surrounding rock.

[0009] Preferably, the degradation effect in S32 is calculated using the following formula: ; ; ; in, , , These are the deformation modulus, cohesion, and internal friction angle of the surrounding rock after deformation and deterioration. , , The initial surrounding rock deformation modulus, cohesion, and internal friction angle are given.

[0010] Preferably, the support method in S4 includes advanced grouting, prestressed anchor bolts, and early high-strength shotcrete.

[0011] Preferably, the stability determination of the unsupported section surrounding rock in S5 includes: S51. Combining the tunnel excavation geometry parameters, original surrounding rock deformation modulus, cohesion, internal friction angle, and in-situ stress parameters, the surrounding rock stability mechanical analysis model is applied to calculate the stress at the bottom of the surrounding rock. and deformation value of excavated surrounding rock size; S52. Determine the stability of the surrounding rock in the unsupported section. If it is stable, proceed with normal construction and stop the calculation. If it is unstable, advance support needs to be set up, the original surrounding rock mechanical parameters need to be adjusted, and return to S51 until it is stable or temporarily stable. If it is temporarily stable, continue to S53. S53, Combined with the deformation value of the surrounding rock during excavation The magnitude of the deformation is calculated using the formula for the effect of surrounding rock deformation on the deterioration of surrounding rock mechanical parameters. The deterioration reduction of these parameters is then applied, and the surrounding rock stability mechanical analysis model is used again for iterative calculations. This yields the dynamic change process of the stability coefficient as the surrounding rock deteriorates with deformation, and the maximum deformation value corresponding to the unstable state of the surrounding rock. .

[0012] Preferably, in step S5, the appropriate support timing is determined by the following formula: ; in, The time difference between the start of surrounding rock excavation and the start of support construction, in hours; The time required for support construction such as anchor bolts and shotcrete, in hours; , , respectively, represent the undetermined coefficients of the fitting, which are obtained by fitting real-time monitoring data of surrounding rock deformation on site.

[0013] Preferably, step S6 includes: combining the parameters of the prestressed anchor bolts and early high-strength shotcrete used in the support, applying the calculation formula for the influence of the support on the mechanical parameters of the surrounding rock, improving the mechanical parameters of the surrounding rock at the time of support, and then applying the mechanical analysis model of the surrounding rock stability to carry out the stress at the bottom of the surrounding rock at different times. and deformation value of excavated surrounding rock The calculation continues until the surrounding rock meets the stability requirements, and the stability coefficient values ​​of the supporting surrounding rock at different times are output.

[0014] Therefore, the above-mentioned active control method for tunnel surrounding rock stability based on spatiotemporal effects, adopted in this invention, has the following beneficial effects: (1) This method takes into account the influence of construction time and space effects on the physical and mechanical parameters of the surrounding rock of the tunnel, and proposes a method for judging the stability state of the surrounding rock with stress and strain as indicators. It can realize the quantitative calculation of the physical and mechanical parameters of the surrounding rock under different states, the appropriate support timing, and the parameters of the appropriate support system.

[0015] (2) This method can achieve active and precise control of the stability of the surrounding rock, reduce the construction safety hazards caused by manual experience methods, and provide scientific guidance for tunnel support design and construction safety.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the division of the spatiotemporal effect influence unit for the active control method of tunnel surrounding rock stability based on spatiotemporal effect according to the present invention; Figure 2 This is a schematic diagram of the mechanical analysis model of tunnel surrounding rock stability based on the active control method of tunnel surrounding rock stability based on spatiotemporal effect of the present invention, wherein (a) is a schematic diagram of the geometric division of the excavated tunnel type, and (b) is the basic unit of mechanical analysis of surrounding rock stability. Figure 3 This is a flowchart illustrating the specific implementation of the active control method for tunnel surrounding rock stability based on spatiotemporal effects according to the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0020] Example Please see Figures 1-3This invention provides an active control method for tunnel surrounding rock stability based on spatiotemporal effects. Using the stress-strain state of the surrounding rock as a stability control index, it presents a method for dividing the unit sections affected by the spatiotemporal effects of surrounding rock stability, constructs a mechanical analysis and calculation model for surrounding rock stability, and proposes quantitative calculation methods for physical and mechanical parameters of tunnel surrounding rock under different states, reasonable support timing, and reasonable support system parameters. Specifically, it includes: S1. Based on the excavation advance length index, the spatiotemporal effects of tunnel surrounding rock stability are divided into unit sections. The spatiotemporal effects of surrounding rock stability are essentially the influence of the changes in the state of excavation and support over time and space during construction (such as excavation advance length, presence or absence of support, timing of support, duration of support action, etc.) on the stress and strain (deformation) state of the surrounding rock. For each excavation advance length, the spatiotemporal effects are consistent. Therefore, this method divides the spatiotemporal effects of surrounding rock stability into unit sections based on the excavation advance length index. The division method and influence characteristics are detailed in [reference needed]. Figure 1 As shown.

[0021] S2. Establish a mechanical analysis model for surrounding rock stability. This method, considering the geometric characteristics of tunnel excavation, divides the tunnel into multi-centered circular arc segments, using each arc segment as the basic unit for surrounding rock mechanical analysis, and establishes a mechanical analysis model for surrounding rock stability, as follows: Figure 2 As shown, the following steps are taken to determine the surrounding rock stability state and surrounding rock stability coefficient in the surrounding rock stability mechanical analysis model: S21. The thickness of the surrounding rock in the mechanical analysis model of surrounding rock stability is taken as the thickness of the excavation influence range. Calculate the thickness of the excavation impact zone. As shown in the following formula: ; in, The radius of the excavated surrounding rock arc segment, in meters; The unit is the cohesion of the surrounding rock, expressed in MPa. The internal friction angle of the surrounding rock is expressed in degrees (°). This represents the initial maximum geostress of the surrounding rock, expressed in MPa.

[0022] S22. Based on the thickness of the excavation influence range, calculate the external loads acting on the surrounding rock in the mechanical analysis model for rock stability, as shown in the following formula: ; ; in, This represents a vertically uniformly distributed load, expressed in MPa. The load is a uniformly distributed horizontal load, in MPa. The angle between the arch line and the horizontal line of the excavated surrounding rock arc segment. , , The height of the arch line for excavating the surrounding rock arc section, in meters; The length of the chord between the starting points of the arched section of the surrounding rock being excavated is in meters (m).

[0023] S23. Based on the external loads acting on the surrounding rock, calculate the stress at the bottom of the surrounding rock in the mechanical analysis model for rock stability, as shown in the following formula: ; in, is the stress at the bottom of the excavated surrounding rock, in MPa; b is the longitudinal unit length of the excavated surrounding rock, taken as 1m. The horizontal constraint force on both sides of the surrounding rock during excavation is expressed in kN.

[0024] Horizontal constraint force on both sides of the excavation surrounding rock Calculate using the following formula: ; ; ; in, The deformation modulus of the surrounding rock is expressed in GPa. Let be the moment of inertia of the surrounding rock section, and take . , The lower edge of the actual load Displacement in direction, in meters (m). unit force Displacement along its direction under action, in meters (m).

[0025] S24. Calculate the deformation value at the bottom of the surrounding rock in the mechanical analysis model of surrounding rock stability. The deformation value at the bottom of the surrounding rock is calculated using the following formula: ; ; ; in, The value represents the deformation of the surrounding rock during excavation, in meters (m). unit force Vertical displacement at the bottom of the arch caused by the action, in meters; The vertical displacement at the bottom of the arch under actual load, expressed in meters (m).

[0026] S25. Determine the stability state of the surrounding rock based on the stress and deformation value at the bottom of the surrounding rock, and calculate the stability coefficient of the surrounding rock.

[0027] The stability state of the surrounding rock is shown in the following formula: ; The surrounding rock stability coefficient is shown in the following formula: ; in, The stress at the bottom of the excavated surrounding rock is expressed in MPa. The ultimate compressive strength of the surrounding rock is expressed in MPa. The value represents the deformation of the surrounding rock during excavation, in meters (m). The ultimate tensile strength of the surrounding rock, in MPa. is the surrounding rock stability coefficient.

[0028] S3. Calculate the impact of surrounding rock deformation on the deterioration of surrounding rock mechanical parameters. This includes: S31. The ratio of the deformation value at the bottom of the surrounding rock to the thickness of the excavation influence range is defined as the surrounding rock deformation rate, which is shown in the following formula: ; in, The value is the deformation rate of the surrounding rock, expressed in % (%). The value represents the deformation of the surrounding rock, in meters (m). The thickness of the affected area is expressed in meters (m). S32. The deterioration effect on the mechanical parameters of the surrounding rock is calculated based on the deformation rate of the surrounding rock. The deterioration effect is calculated using the following formula: ; ; ; in, , , These are the deformation modulus, cohesion, and internal friction angle of the surrounding rock after deformation and deterioration. , , The initial surrounding rock deformation modulus, cohesion, and internal friction angle are given.

[0029] S4. Analyze the influence of support methods on the control of surrounding rock mechanical parameters. In this embodiment, the support methods include advanced grouting, prestressed anchor bolts, and early high-strength shotcrete. The calculation formulas for the influence of the above three types of support methods on the control of surrounding rock mechanical parameters include: (1) The influence of advanced bottom grouting support on the mechanical parameters of the surrounding rock is shown in the following formula: ; ; in, , These represent the increases in the deformation modulus and cohesion of the surrounding rock under grouting conditions; The thickness of the grouting around the cave, in meters; , These are the deformation modulus and cohesive force of the slurry after solidification, respectively. This represents the filling rate of the grout in the surrounding rock, expressed in %. The value is related to the geological conditions; for rocky strata, it can be 1-5%; for soil strata, it can be 20-60%.

[0030] (2) The influence of prestressed anchor bolt support method on the mechanical parameters of surrounding rock is shown in the following formula: ; ; ; ; in, , , These represent the increments of the surrounding rock deformation modulus, cohesion, and internal friction angle under the action of the anchor bolts; The thickness of the anchorage zone for anchor bolt operation, in meters (m). Sl represents the preload of the anchor bolt, in MN; Sl and Sr represent the longitudinal and circumferential spacing of the anchor bolt, in meters; L represents the length of the free section of the anchor bolt, in meters; B represents the width of the anchor bolt pad, in meters. , These are the undetermined coefficients for fitting the deformation modulus of the surrounding rock. , These are the undetermined coefficients for fitting the cohesion of the surrounding rock. , The coefficients for fitting the internal friction angle of the surrounding rock are undetermined and are all related to the lithology of the surrounding rock. They can be obtained from the indoor triaxial test of the surrounding rock.

[0031] (3) The influence of early high-strength shotcrete support on the mechanical parameters of the surrounding rock is shown in the following formula: ; in, This represents the increase in the deformation modulus of the surrounding rock under the action of shotcrete. The deformation modulus of the surrounding rock before the application of shotcrete; The shear strength between the shotcrete and the surrounding rock is expressed in MPa, and the calculation formula is as follows: ; in, The tensile strength of shotcrete is expressed in MPa. For the roughness of the contact surface between the shotcrete and the surrounding rock, 11 can be used for Class III surrounding rock, 9.45 for Class IV surrounding rock, and 7.91 for Class V surrounding rock.

[0032] For early high-strength shotcrete, the formulas for calculating the tensile strength at different ages are as follows: ; in, T represents the tensile strength of shotcrete at age T, in MPa; T represents the age in days.

[0033] S5. Conduct a stability assessment of the unsupported section's surrounding rock and determine the appropriate timing for support. The stability assessment of the unsupported section's surrounding rock includes: S51. Combining the tunnel excavation geometry parameters, original surrounding rock deformation modulus, cohesion, internal friction angle, and in-situ stress parameters, the surrounding rock stability mechanical analysis model is applied to calculate the stress at the bottom of the surrounding rock. and deformation value of excavated surrounding rock size; S52. Determine the stability of the surrounding rock in the unsupported section. If it is stable, proceed with normal construction and stop the calculation. If it is unstable, advance support (such as advance grouting) needs to be set up, the original surrounding rock mechanical parameters need to be adjusted, and return to S51 until it is stable or temporarily stable. If it is temporarily stable, continue with S53. S53, Combined with the deformation value of the surrounding rock during excavation The magnitude of the deformation is calculated using the formula for the effect of surrounding rock deformation on the deterioration of surrounding rock mechanical parameters. The deterioration reduction of these parameters is then applied, and the surrounding rock stability mechanical analysis model is used again for iterative calculations. This yields the dynamic change process of the stability coefficient as the surrounding rock deteriorates with deformation, and the maximum deformation value corresponding to the unstable state of the surrounding rock. .

[0034] In S5, the appropriate timing for support is determined by the following formula: ; in, The time difference between the start of surrounding rock excavation and the start of support construction, in hours; The time required for support construction such as anchor bolts and shotcrete, in hours; , , respectively, represent the undetermined coefficients of the fitting, which are obtained by fitting real-time monitoring data of surrounding rock deformation on site.

[0035] S6. Determine the stability of the surrounding rock in the support section. Based on the parameters of the prestressed anchors and early high-strength shotcrete used in the support, apply the calculation formula for the influence of the support on the mechanical parameters of the surrounding rock, and adjust the mechanical parameters of the surrounding rock at the support time. Then, apply the mechanical analysis model of surrounding rock stability to calculate the stress at the bottom of the surrounding rock at different times. and deformation value of excavated surrounding rock The calculation continues until the surrounding rock meets the stability requirements, and the stability coefficient values ​​of the supporting surrounding rock at different times are output.

[0036] In specific implementation, when using the method proposed in this invention for active control of surrounding rock stability, such as... Figure 3 As shown, the main implementation methods are as follows: Step 1: Combining the geometric dimensions of the tunnel excavation, and based on the original surrounding rock deformation modulus, cohesion, internal friction angle, and ground stress values, apply the surrounding rock stability mechanical analysis model to obtain the bottom stress and strain values ​​of the surrounding rock during excavation, and evaluate the stability state of the surrounding rock during excavation. Step 2: When the excavated surrounding rock is in a stable state, output the stability coefficient of the surrounding rock; when the excavated surrounding rock is in an unstable state, it is necessary to take pre-reinforcement measures to enhance the mechanical parameters of the surrounding rock until the surrounding rock is stable or temporarily stable; when the excavated surrounding rock is in a temporarily stable state, the influence of surrounding rock deformation on the deterioration of the mechanical parameters of the surrounding rock is processed, and the maximum deformation value corresponding to the instability of the surrounding rock is obtained through iterative calculation. Combined with the analysis of the time-effect monitoring data of the surrounding rock deformation, the appropriate support timing is determined. Step 3: Combine the design parameters of prestressed anchor bolts and early high-strength shotcrete to adjust and enhance the mechanical parameters of the surrounding rock, and conduct a stability evaluation of the surrounding rock. Step 4: When the supporting surrounding rock is in a stable state, output the surrounding rock stability coefficient result; when the supporting surrounding rock is in a temporarily stable state, optimize and adjust the support parameters until the surrounding rock is in a stable state.

[0037] This method can be used to quantitatively calculate the mechanical parameters of surrounding rock under different conditions, as well as to quantitatively calculate the stability of tunnel surrounding rock, the appropriate timing of support, and the design of support parameters. It has strong applicability and economic value.

[0038] Therefore, this invention adopts the above-mentioned active control method for tunnel surrounding rock stability based on spatiotemporal effects. Based on the control of surrounding rock stress and strain state, it analyzes the deterioration and regulation effects of construction spatiotemporal effects on the mechanical parameters of surrounding rock. On the basis of effectively ensuring the stability of surrounding rock, it realizes the quantitative calculation of physical and mechanical parameters of surrounding rock under different states, reasonable support timing, and reasonable support system parameters, thereby improving the accuracy and scientific nature of tunnel surrounding rock stability control.

[0039] 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 method for active control of tunnel surrounding rock stability based on space-time effect, characterized in that, Includes the following steps: S1. Based on the excavation advance length index for each stage, the spatiotemporal effects of the surrounding rock stability of the tunnel are divided into unit sections. S2. Establish a mechanical analysis model for the stability of the surrounding rock; S3. Calculate the effect of surrounding rock deformation on the deterioration of surrounding rock mechanical parameters; S4. Analyze the influence of support methods on the regulation of surrounding rock mechanical parameters; S5. Conduct a stability assessment of the unsupported section of surrounding rock and determine the appropriate timing for support. S6. Determine the stability of the surrounding rock in the support section.

2. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 1, characterized in that, The S2 includes: combining the geometric characteristics of the tunnel excavation, dividing the tunnel into multi-centered circular arc segments, taking each arc segment as the basic unit for surrounding rock mechanics analysis, establishing a surrounding rock stability mechanics analysis model, and determining the surrounding rock stability state and surrounding rock stability coefficient in the surrounding rock stability mechanics analysis model.

3. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 2, characterized in that: In step S2, determining the surrounding rock stability state and surrounding rock stability coefficient in the surrounding rock stability mechanical analysis model includes the following steps: S21. Take the thickness of the surrounding rock in the mechanical analysis model of surrounding rock stability as the thickness of the excavation influence range, and calculate the thickness of the excavation influence range. S22. Based on the thickness of the excavation influence range, calculate the external loads acting on the surrounding rock in the mechanical analysis model of surrounding rock stability; S23. Calculate the stress at the bottom of the surrounding rock in the mechanical analysis model of surrounding rock stability based on the external loads acting on the surrounding rock. S24. Calculate the deformation value at the bottom of the surrounding rock in the mechanical analysis model of surrounding rock stability; S25. Determine the stability state of the surrounding rock based on the stress and deformation value at the bottom of the surrounding rock, and calculate the stability coefficient of the surrounding rock.

4. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 3, characterized in that, The stability state of the surrounding rock in S25 is shown in the following formula: ； The surrounding rock stability coefficient is shown in the following formula: ； in, The stress at the bottom of the excavated surrounding rock is expressed in MPa. The ultimate compressive strength of the surrounding rock is given in MPa. The value represents the deformation of the surrounding rock during excavation, in meters (m). The ultimate tensile strength of the surrounding rock, in MPa. is the surrounding rock stability coefficient.

5. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 4, characterized in that, S3 includes: S31. The ratio of the deformation value at the bottom of the surrounding rock to the thickness of the excavation influence range is defined as the surrounding rock deformation rate, which is shown in the following formula: ； in, The value is the deformation rate of the surrounding rock, expressed in % (%). The value represents the deformation of the surrounding rock, in meters (m). The thickness of the affected area is expressed in meters (m). S32. The deterioration effect on the mechanical parameters of the surrounding rock is calculated based on the deformation rate of the surrounding rock.

6. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 5, characterized in that, The degradation effect in S32 is calculated using the following formula: ； ； ； in, , , These are the deformation modulus, cohesion, and internal friction angle of the surrounding rock after deformation and deterioration. , , The initial surrounding rock deformation modulus, cohesion, and internal friction angle are given.

7. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 6, characterized in that: The support methods in S4 include advanced grouting, prestressed anchor bolts, and early high-strength shotcrete.

8. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 7, characterized in that, The stability assessment of the unsupported surrounding rock section in S5 includes: S51. Combining the tunnel excavation geometry parameters, original surrounding rock deformation modulus, cohesion, internal friction angle, and in-situ stress parameters, the surrounding rock stability mechanical analysis model is applied to calculate the stress at the bottom of the surrounding rock. and deformation value of excavated surrounding rock size; S52. Determine the stability of the surrounding rock in the unsupported section. If it is stable, proceed with normal construction and stop the calculation. If it is unstable, advance support needs to be set up, the original surrounding rock mechanical parameters need to be adjusted, and return to S51 until it is stable or temporarily stable. If it is temporarily stable, continue to S53. S53, Combined with the deformation value of the surrounding rock during excavation The magnitude of the deformation is calculated using the formula for the effect of surrounding rock deformation on the deterioration of surrounding rock mechanical parameters. The deterioration reduction of these parameters is then applied, and the surrounding rock stability mechanical analysis model is used again for iterative calculations. This yields the dynamic change process of the stability coefficient as the surrounding rock deteriorates with deformation, and the maximum deformation value corresponding to the unstable state of the surrounding rock. .

9. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 8, characterized in that, In S5, the appropriate support timing is determined by the following formula: ； in, The time difference between the start of surrounding rock excavation and the start of support construction, in hours; The time required for support construction such as anchor bolts and shotcrete, in hours; , , respectively, represent the undetermined coefficients of the fitting, which are obtained by fitting real-time monitoring data of surrounding rock deformation on site.

10. The active control method for tunnel surrounding rock stability based on spatiotemporal effects according to claim 9, characterized in that, S6 includes: combining the parameters of the prestressed anchors and early high-strength shotcrete used in the support, applying the calculation formula for the influence of the support on the mechanical parameters of the surrounding rock, improving the mechanical parameters of the surrounding rock at the time of support, and then applying the mechanical analysis model of surrounding rock stability to carry out the stress at the bottom of the surrounding rock at different times. and deformation value of excavated surrounding rock The calculation continues until the surrounding rock meets the stability requirements, and the stability coefficient values ​​of the supporting surrounding rock at different times are output.

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