Active control support structure system for tunnel deformation and parameter solving method

Abstract

The present invention discloses an active control support structure system for tunnel deformation and a parameter solving method, which comprises the following steps: establishing a structural safety deformation control benchmark corresponding to different tunnel deformation levels; establishing a deformation coordination equation for the collaborative bearing of active support components and passive support components; determining active support parameters based on the deformation control effect of the active support components of the tunnel; formulating a number of passive support parameters within the value range of the passive support parameters; using the deformation coordination equation to output the tunnel deformation amount; comparing the tunnel deformation amount with the deformation control benchmark: if the tunnel deformation amount is within the deformation control benchmark, output the corresponding passive support parameters and active support parameters; if the tunnel deformation amount is not within the deformation control benchmark, return to formulate the passive support parameters anew. The present invention provides a method for accurately calculating the active support and passive support parameters, enabling the surrounding rock - support structure system in the tunnel to reach a stable, coordinated and safe long-term healthy state.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel engineering, and particularly to a tunnel deformation active control support structure system and a parameter solving method thereof. Background Art

[0002] Currently, in tunnel construction, the passive support effects of primary support and secondary lining are generally emphasized. However, practice has proved that when facing complex geological environments such as soft surrounding rock, water-rich strata, and high in-situ stress, strengthening the passive support parameters has an unsatisfactory effect on controlling the deformation of the surrounding rock, and a series of engineering disasters such as large deformation, distortion of steel arch frames, spalling of shotcrete, and breakage of bolts still occur in the tunnel. In recent years, in response to this problem, active support systems have been gradually emphasized at home and abroad to achieve active regulation of deformation.

[0003] The tunnel active support system is to actively regulate the deformation of the surrounding rock by adopting a series of technical means, aiming to make the final displacement reach the ideal target value through artificial intervention in the tunnel deformation process, and make the surrounding rock - support structure system reach a stable, coordinated, and safe long-term healthy state. Currently, active support measures are divided into two categories:

[0004] (1) Applying radial active support force to the surrounding rock, such as prestressed bolts, prestressed cables, etc.;

[0005] (2) Actively modifying the surrounding rock, such as grouting with advanced small pipes / bolts, radial grouting of the surrounding rock, etc.

[0006] However, for this emerging active support system, there is currently no systematic method to determine the support parameters that can ensure the synergistic effect of active support and traditional passive support in different geological environments. The main problems in calculating the active support system and parameters in the prior art are as follows:

[0007] (1) An effective deformation control criterion has not been established as the determination standard for support parameters;

[0008] (2) A method for determining active support parameters has not been proposed;

[0009] (3) There is no solution for solving the support parameters that can ensure the synergistic effect of active support and traditional passive support. Summary of the Invention

[0010] In view of the above deficiencies of the prior art, the present invention provides a tunnel deformation active control support structure system and a parameter solving method thereof, which actively regulate the deformation of the surrounding rock by adding active support components to the existing passive support system, and solve the problem of solving the support parameters for the synergistic bearing of the active support system and the passive support system.

[0011] To achieve the above invention purpose, the technical solution adopted by the present invention is:

[0012] Provide an active control support structure system for tunnel deformation and a parameter solving method, which includes the following steps:

[0013] S1: Statistically analyze the cracking ratio of the structure under different tunnel deformation levels, determine the upper limit statistical value of the deformation when the tunnel structure does not crack, and obtain the structural safety deformation control benchmarks corresponding to different tunnel deformation levels;

[0014] S2: Establish a deformation coordination equation for the collaborative bearing of the active support components and the passive support components;

[0015] S3: Determine the active support parameters based on the deformation control effect of the active support components of the tunnel;

[0016] S4: Establish the value range of the passive support parameters, and formulate several passive support parameters within the value range of the passive support parameters;

[0017] S5: Convert one of the formulated passive support parameters and the active support parameters into the corresponding support forces, substitute the support forces into the deformation coordination equation, and output the tunnel deformation amount;

[0018] S6: Compare the tunnel deformation amount with the deformation control benchmark:

[0019] If the tunnel deformation amount is within the deformation control benchmark, output the corresponding passive support parameters and active support parameters;

[0020] If the tunnel deformation amount is not within the deformation control benchmark, execute step S7;

[0021] S7: Return to step S5, reselect a passive support parameter from several passive support parameters and execute steps S5 - S6 until the corresponding passive support parameters and active support parameters that make the tunnel deformation amount within the deformation control benchmark are output.

[0022] Furthermore, the deformation coordination equation is:

[0023]

[0024] Among them, Both k and α are conversion coefficients, is the internal friction angle, R0 is the tunnel diameter, p s is the support reaction force of the initial support, c is the rock cohesion, p g is the initial in - situ stress, u(∞) is the final value of the free deformation of the surrounding rock without the support structure, x is the distance from the tunnel face when the support structure is applied, p y is the support reaction force of the active support component, <p sa > is the ultimate support reaction force when the steel arch yields, and in other cases <p sa>Take 0, <p rb >is the ultimate support reaction force when the bolt yields, and in other cases <p rb >Take 0, K pr is the initial support stiffness;

[0025] The support reaction force p of the active support component y is the active support parameter, (p s -p y ) is the passive support parameter.

[0026] Furthermore, step S4 includes:

[0027] S41: Taking the designed passive support parameter as the upper limit and the passive support parameter of the next surrounding rock level as the lower limit, establish the value range of the passive support parameter;

[0028] S42: Determine several passive support parameters in the value range of the passive support parameter in the way of equal-proportion stiffness reduction.

[0029] Furthermore, step S3 includes

[0030] S31: Taking the prestressed bolt system parameters with the best comprehensive deformation control effect and economic benefit as the bolt prestress parameters for different surrounding rock levels and different burial depths;

[0031] S32: Taking the advanced small pipe or advanced pipe shed parameters with the best comprehensive deformation control effect and economic benefit as the advanced support parameters for different surrounding rock levels and different burial depths;

[0032] S33: The bolt prestress parameters and the advanced support parameters are both active support parameters.

[0033] The beneficial effects of the present invention are as follows: The present invention establishes a deformation control criterion by statistically counting the proportion of structural cracks, and uses it as a standard to evaluate whether the collaborative bearing structure of the support and the passive support is safe and stable. The active support parameters are determined by the deformation control effects of the prestressed bolts and the advanced small pipes / pipe sheds in the active support components. And a deformation solution equation for the active and passive collaborative bearing is pioneered. By adjusting the single variable of the passive support parameter, the tunnel deformation amount is dynamically solved. Finally, the ultimate active support and passive support parameters are determined based on whether the deformation amount value passes the deformation control criterion. During the process of the collaborative bearing of the active support and the passive support for the tunnel, the present invention provides a method for accurately calculating the active support and passive support parameters, so that the surrounding rock-support structure system in the tunnel reaches a stable, coordinated and safe long-term healthy state. Brief Description of the Drawings

[0034] Figure 1 is the flow chart of the tunnel deformation active control support structure system and parameter solution method.

[0035] Figure 2 Schematic diagram for determining the deformation control reference range

[0036] Figure 3 Effect diagram of deformation control with different prestresses of anchor bolts

[0037] Figure 4 Effect diagram of deformation control with different lengths of advanced small pipes

[0038] Figure 5 Result diagram for solving the deformation coordination equation Specific implementation manners

[0039] The following describes the specific implementation manners of the present invention to facilitate those skilled in the art of this technical field to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation manners. For those of ordinary skill in the art of this technical field, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions created using the concept of the present invention are within the scope of protection.

[0040] As Figure 1 shown, the tunnel deformation active control support structure system and parameter solving method of this solution include the following steps:

[0041] S1: Count the cracking proportion of the structure under different tunnel deformation grades, determine the upper limit statistical value of the deformation under the condition that the tunnel structure does not crack, and obtain the structural safety deformation control reference corresponding to different tunnel deformation grades;

[0042] S2: Establish a deformation coordination equation for the collaborative bearing of the active support component and the passive support component:

[0043]

[0044] Wherein, both k and α are conversion coefficients, is the internal friction angle, R0 is the tunnel diameter, p s is the support reaction force of the primary support, c is the rock cohesion, p g is the initial ground stress, u(∞) is the final value of the free deformation of the surrounding rock without the support structure, x is the distance from the face when the support structure is applied, p y is the support reaction force of the active support component, <p sa > is the ultimate support reaction force when the steel arch yields, and in other cases <p sa > takes 0, <p rb > is the ultimate support reaction force when the anchor bolt yields, and in other cases <p rb > takes 0, K pr is the primary support stiffness;

[0045] The support reaction force p of the active support member y is the active support parameter, (p s - p y ) is the passive support parameter.

[0046] S3: Determine the active support parameters based on the deformation control effect of the active support members of the tunnel; Step S3 specifically includes:

[0047] S31: Take the prestressed anchor bolt system parameters with the optimal comprehensive deformation control effect and economic benefit as the bolt prestress parameters for different surrounding rock grades and different burial depth levels;

[0048] S32: Take the advanced small ducts or advanced pipe shed parameters with the optimal comprehensive deformation control effect and economic benefit as the advanced support parameters for different surrounding rock grades and different burial depth levels.

[0049] S33: Both the bolt prestress parameters and the advanced support parameters are active support parameters.

[0050] S4: Establish the value range of the passive support parameters, and draw up several passive support parameters within the value range of the passive support parameters; Step S4 specifically includes:

[0051] S41: Take the designed passive support parameters as the upper limit and the passive support parameters of the next surrounding rock grade as the lower limit to establish the value range of the passive support parameters;

[0052] S42: Draw up several passive support parameters within the value range of the passive support parameters in the way of equal-proportion stiffness reduction.

[0053] S5: Convert one of the drawn passive support parameters and the active support parameters into the corresponding support forces, substitute the support forces into the deformation coordination equation, and output the tunnel deformation amount;

[0054] S6: Compare the tunnel deformation amount with the deformation control criterion:

[0055] If the tunnel deformation amount is within the deformation control criterion, output the corresponding passive support parameters and active support parameters;

[0056] If the tunnel deformation amount is not within the deformation control criterion, execute Step S7;

[0057] S7: Return to Step S5, reselect a passive support parameter from several passive support parameters to execute Steps S5 - S6 until the corresponding passive support parameters and active support parameters that make the tunnel deformation amount within the deformation control criterion are output.

[0058] Now take a certain tunnel project as an example to discuss the application effect of calculating the passive support parameters and active support parameters of the present invention.

[0059] The confining pressure level of this tunnel project is level V, the buried depth is about 500 m, the tunnel diameter is 5.4 m, the initial in-situ stress field is about 13 MPa, the surrounding rock strength-stress ratio is 0.66, and the measured maximum deformation is 22.7 cm, belonging to slightly large deformation (strength-stress ratio range 0.8 - 0.6).

[0060] The structural mechanical states of a total of 68 tunnel cross-sections within the slightly large deformation level were statistically analyzed, as Figure 2 shown. As can be seen from Figure 2 , the first cracked cross-section appears when the tunnel deformation reaches 200 - 250 mm. Thus, the deformation control criterion for slightly large deformation can be determined as 200 - 250 mm.

[0061] The control effects of different prestressed parameters on tunnel deformation were calculated using numerical simulation software. The parameters used in the calculation are shown in Tables 1 and 2 below, and the calculation results are as Figure 3 shown. When the prestress reaches 60 KN, the tunnel displacement can be controlled within the control criterion of 200 mm, and the deformation control effect is significant, the parameters are economically reasonable, and the comprehensive benefits are optimal. Thus, the parameter of the prestressed anchor rod can be determined as 60 KN.

[0062] Table 1

[0063]

[0064]

[0065] Table 2

[0066] Name Elastic modulus Poisson's ratio Density Cohesion Internal friction angle Shotcrete 23 GPa 0.23 <![CDATA[2200Kg / m 3 > / / Bolt 200 GPa / <![CDATA[7850 Kg / m 3 > / / Steel arch 183 GPa / <![CDATA[7836 Kg / m 3 > / / Surrounding rock parameters 1.5 GPa 0.4 <![CDATA[1850 Kg / m 3 > 0.13 MPa 23.5° Grouting parameters 5.7 GPa 0.31 <![CDATA[2275 Kg / m 3 > 0.7 MPa 40°

[0067] The control effects of different advanced small pipe parameters on tunnel deformation were calculated using numerical simulation software, as Figure 4 shown. When the parameters of the advanced small pipe are pipe diameter φ42 mm and length 4 m, the tunnel displacement can be controlled within the control criterion of 200 mm, and the deformation control effect is significant, the parameters are economically reasonable, and the comprehensive benefits are optimal. Thus, the parameters of the advanced support can be determined as an advanced small pipe with a pipe diameter of φ42 mm and a length of 4 m.

[0068] Based on the recommended values in the design code for deep-buried tunnels in grade V surrounding rock (shown in Table 1), partial passive support schemes were formulated after reduction, as shown in Table 3.

[0069] Table 3

[0070]

[0071] Substitute the active support parameters and passive support parameters of each scheme in Table 2 into the deformation coordination equation for solution. The parameters involved in the calculation can be transformed through the parameters in Table 1, Table 2 and Table 3. The calculation results are as Figure 5 shown. When Scheme 3 is adopted, the tunnel deformation can be controlled within the deformation control benchmark of 200 mm, and this is used as the support parameters of the active support system. Thus, the active control of the surrounding rock is achieved by adding active support members and weakening passive support members.

[0072] The present invention uses the deformation control benchmark established by statistically counting the proportion of structural cracks as the standard for evaluating whether the collaborative bearing structure of the support and the passive support is safe and stable. The active support parameters are determined by the deformation control effects of the prestressed anchor bolts and the advanced small ducts / pipe roofs in the active support members. And an innovative deformation solution equation for the active and passive collaborative bearing is established. By regulating the single variable of the passive support parameters, the tunnel deformation amount is dynamically solved. Finally, the final active support and passive support parameters are determined based on whether the deformation value passes the deformation control benchmark. During the process of the active support and the passive support of the tunnel bearing collaboratively, the present invention provides a method for accurately calculating the active support and passive support parameters, enabling the surrounding rock-support structure system in the tunnel to reach a stable, coordinated and safe long-term healthy state.

Claims

1. A method for solving parameters of an active control support structure system for tunnel deformation, characterized in that, It includes the following steps: S1: Statistically analyze the proportion of structural cracks under different tunnel deformation levels, determine the upper limit statistical value of deformation under the condition that the tunnel structure does not crack, and obtain the structural safety deformation control benchmarks corresponding to different tunnel deformation levels; S2: Establish a deformation coordination equation for the collaborative bearing of active support members and passive support members; S3: Determine the active support parameters based on the deformation control effect of the active support members of the tunnel; S4: Establish a value range for the passive support parameters, and formulate several passive support parameters within the value range of the passive support parameters; S5: Convert one of the formulated passive support parameters and the active support parameters into corresponding support forces, substitute the support forces into the deformation coordination equation, and output the tunnel deformation amount; S6: Compare the tunnel deformation amount with the deformation control benchmark: If the tunnel deformation amount is within the deformation control benchmark, output the corresponding passive support parameters and active support parameters; If the tunnel deformation amount is not within the deformation control benchmark, execute step S7; S7: Return to step S5, reselect a passive support parameter within several passive support parameters and execute steps S5 - S6 until the passive support parameters and active support parameters corresponding to the tunnel deformation amount within the deformation control benchmark are output; The deformation coordination equation is: Among them, , , k and α are all conversion coefficients, is the angle of internal friction, R 0 is the tunnel diameter, is the supporting reaction force of the initial support, c is the rock cohesion, is the initial in-situ stress, is the final value of the free deformation of the surrounding rock without a support structure, x is the distance from the tunnel face when the support structure is applied, is the supporting reaction force of the active support member, is the ultimate supporting reaction force when the steel arch yields, and in other cases is taken as 0, is the ultimate supporting reaction force when the bolt yields, and in other cases is taken as 0, is the initial support stiffness; The support reaction force of the active support component is the active support parameter, which is the passive support parameter.

2. The parameter solving method of the active control support structure system for tunnel deformation according to claim 1, characterized in that, The step S4 includes: S41: Establish a value range for the passive support parameters with the designed passive support parameters as the upper limit and the passive support parameters of the next surrounding rock level as the lower limit; S42: Formulate several passive support parameters within the value range of the passive support parameters in the way of equal - proportion stiffness reduction.

3. The parameter solution method of the active control support structure system for tunnel deformation according to claim 1, characterized in that, The step S3 includes: S31: Take the prestressed anchor system parameters with the optimal comprehensive deformation control effect and economic benefit as the anchor prestress parameters for different surrounding rock levels and different buried depth levels; S32: Take the advanced small pipes or advanced pipe - shed parameters with the optimal comprehensive deformation control effect and economic benefit as the advanced support parameters for different surrounding rock levels and different buried depth levels; S33: The anchor prestress parameters and the advanced support parameters are both active support parameters.

Images