CN-122020794-A - Sprayed concrete support parameter adaptive design method considering blasting damage

CN122020794ACN 122020794 ACN122020794 ACN 122020794ACN-122020794-A

Abstract

The invention relates to an adaptive design method for shotcrete support parameters considering blasting damage, and belongs to the technical field of tunnel engineering. The problems that in the prior art, the friction coefficient is experienced due to the fact that the surrounding rock surface morphology changes caused by blasting damage are ignored, the parameter design is not matched with the actual working condition, and the design accuracy is low are solved. The method comprises the steps of quantifying surrounding rock roughness coefficient through multi-angle image acquisition and image recognition, calculating friction coefficient, determining lining thickness by combining clearance requirement, deformation reserve quantity and blasting damage risk, establishing a two-way unequal pressure elastic mechanical model, solving lining stress distribution based on a stress function and coulomb friction constraint, and reversely solving optimal concrete strength grade and reinforcement ratio by adopting an optimization algorithm with the aim of minimizing supporting cost. The invention realizes accurate self-adaptive design of support parameters, improves stress calculation precision, ensures safety and reduces cost.

Inventors

WU MENGJUN
CAO PENG
WU QINGLIANG
HU XUEBING
GUO HONGYAN
CHEN LIANGJIAN
ZHOU CHENYI
LIU DONGXING

Assignees

招商局重庆交通科研设计院有限公司

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (10)

1. A method for adaptively designing shotcrete support parameters in consideration of blasting damage is characterized by comprising the following steps: step one, performing multi-angle image acquisition on the surface of tunnel surrounding rock after blasting excavation, extracting the surface profile of the surrounding rock through an image recognition technology, and calculating the surface roughness coefficient of the surrounding rock based on the extracted profile Calculating the friction coefficient of the surrounding rock and lining interface according to a preset quadratic polynomial formula ; Step two, combining the tunnel design clearance requirement, surrounding rock deformation reserve and blasting damage spalling risk, and determining the minimum design thickness of the sprayed concrete lining through clearance matching calculation ; Step three, simplifying the surrounding rock-lining structure into a two-way unequal pressure elastic mechanical model with circular holes in infinite mass, adopting a stress function to establish a control equation, introducing nonlinear constraint conditions based on a coulomb friction model, and solving lining stress distribution by a numerical optimization method; and step four, based on the lining stress distribution obtained in the step three, establishing an optimization equation aiming at minimizing the support cost, reversely solving the strength grade and the reinforcement ratio of the sprayed concrete, and solving the optimal parameters through the optimization algorithm to complete the support parameter adaptability design.
2. The method for adaptively designing shotcrete support parameters considering blast damage as set forth in claim 1, wherein in the first step, the roughness coefficient is as follows The calculation formula of (2) is Wherein The actual surface appearance area of the surrounding rock structure surface is represented, Representing the nominal area of the surrounding rock surface.
3. The method for adaptively designing shotcrete support parameters considering blast damage according to claim 2, wherein in the first step, the friction coefficient is as follows The calculation formula of (2) is 。
4. The method for adaptively designing shotcrete support parameters considering blast damage according to claim 1, wherein in the second step, the minimum design thickness is set The calculation formula of (2) is Wherein Representing the maximum difference between the actual contour of the surrounding rock and the design clearance line, The deformation reserved quantity of the surrounding rock is represented, Indicating the burst damage spalling reserve.
5. The method for adaptively designing shotcrete support parameters considering blast damage as set forth in claim 1, wherein in the third step, the stress function Represented as Wherein And Respectively the radius and angle of any point on the tunnel, Is a coefficient to be determined.
6. The method for adaptively designing shotcrete support parameters considering blast damage according to claim 5, wherein in the third step, the control equation comprises 13 equations which are uniquely established based on stress boundary conditions, displacement boundary conditions and undetermined coefficients, and the numerical optimization method is solved by adopting fmincon functions of MATLAB software.
7. The method for adaptively designing shotcrete support parameters with blast damage being considered as set forth in claim 6, wherein in the third step, the nonlinear constraint condition is established based on a coulomb friction model, and the expression is that Wherein Representing the radial stress of the steel sheet, Representing tangential shear stress.
8. The method for adaptively designing shotcrete support parameters considering blast damage according to claim 1, wherein in the fourth step, the objective function of the optimization equation is that Wherein The loss coefficient of concrete construction is represented, The volume of the lining is represented by, The unit price of the concrete is represented, The loss coefficient of the construction of the steel bar is represented, Indicating the total mass of the reinforcing steel bar, Indicating the unit price of the steel bar.
9. The method for adaptively designing shotcrete support parameters considering blast damage according to claim 8, wherein in the fourth step, the optimization algorithm is solved by adopting a particle swarm optimization algorithm PSO.
10. The method for adaptively designing shotcrete support parameters with blast damage being considered as set forth in claim 1, wherein in the fourth step, the reversely calculated shotcrete strength level and reinforcement ratio are required to satisfy the constraint condition of tangential shear stress Hoop normal stress And (2) and Wherein The standard value of the compressive strength of the concrete axle center is indicated.

Description

Sprayed concrete support parameter adaptive design method considering blasting damage Technical Field The invention belongs to the technical field of tunnel engineering, and relates to an adaptive design method for shotcrete support parameters considering blasting damage. Background After tunnel blasting excavation, the surface morphology of surrounding rock has obvious irregularity, and the roughness of the surface morphology directly influences the interfacial friction characteristic of surrounding rock and sprayed concrete lining, so that the bearing efficiency of the associated supporting structure is improved. The existing tunnel shotcrete lining design method depends on engineering experience or simplified mechanical model, the actual form change of the surrounding rock surface caused by blasting damage cannot be fully considered, the influence of the surrounding rock roughness on the contact friction coefficient and the stress distribution is ignored, and the support parameter design is not matched with the actual engineering working condition. Such mismatch manifests itself as low design accuracy and poor adaptability, often resulting in insufficient bearing efficiency or cost waste of the support structure. In the traditional design method, quantitative analysis of the surface roughness of surrounding rock is relatively lacking, and friction coefficient values are usually based on empirical assumption and cannot be accurately calculated by combining with the actual profile after blasting damage. In addition, in the lining thickness determining process, comprehensive consideration of clearance requirements, surrounding rock deformation reserved quantity and blasting damage spalling risks is insufficient, and design conservation or safety risks are easy to cause. In the aspect of mechanical models, the prior art adopts a simplified assumption, and friction characteristics between surrounding rock and lining interfaces and two-way unequal stress conditions are not fully considered, so that stress distribution calculation deviates from reality. The invention aims to solve the technical problems, and the image recognition technology is introduced to quantify the surface roughness of the surrounding rock, and the mechanical analysis and the optimization algorithm are combined to realize the self-adaptive optimization design of the support parameters, so that the adaptability of the support structure to the actual engineering is improved. Disclosure of Invention In view of the above, the present invention aims to provide a method for adaptively designing shotcrete support parameters in consideration of blast damage. By precisely quantifying the surface characteristics of surrounding rock after blasting and combining mechanical analysis and optimization calculation, the support parameters of the adaptation are reversely calculated, and the suitability of the support structure design and engineering reality is improved. In order to achieve the above purpose, the present invention provides the following technical solutions: a method for adaptively designing shotcrete support parameters in consideration of blasting damage comprises the following steps: step one, performing multi-angle image acquisition on the surface of tunnel surrounding rock after blasting excavation, extracting the surface profile of the surrounding rock through an image recognition technology, and calculating the surface roughness coefficient of the surrounding rock based on the extracted profile Calculating the friction coefficient of the surrounding rock and lining interface according to a preset quadratic polynomial formula; Step two, combining the tunnel design clearance requirement, surrounding rock deformation reserve and blasting damage spalling risk, and determining the minimum design thickness of the sprayed concrete lining through clearance matching calculation; Step three, simplifying the surrounding rock-lining structure into a two-way unequal pressure elastic mechanical model with circular holes in infinite mass, adopting a stress function to establish a control equation, introducing nonlinear constraint conditions based on a coulomb friction model, and solving lining stress distribution by a numerical optimization method; and step four, based on the lining stress distribution obtained in the step three, establishing an optimization equation aiming at minimizing the support cost, reversely solving the strength grade and the reinforcement ratio of the sprayed concrete, and solving the optimal parameters through the optimization algorithm to complete the support parameter adaptability design. Further, in step one, the roughness coefficientThe calculation formula of (2) isWhereinThe actual surface appearance area of the surrounding rock structure surface is represented,Representing the nominal area of the surrounding rock surface. Further, in step one, the coefficient of frictionThe calculation formula of (2) is。 Further, in ste