CN-122020771-A - Tunnel blasting excavation and support equivalent simulation method based on three-dimensional finite difference

CN122020771ACN 122020771 ACN122020771 ACN 122020771ACN-122020771-A

Abstract

The application relates to a three-dimensional finite difference-based tunnel blasting excavation and support equivalent simulation method, which comprises the steps of constructing a three-dimensional finite difference model, determining surrounding rock parameters, obtaining exponential stress time-course load by calculating the time-course form of equivalent peak load and blasting load, obtaining a simulation result by simulating ground stress transient unloading based on the coupling, equivalent an anchor bolt support area to be the thickness of a reinforcing ring, equivalent the combined action of sprayed concrete and a steel arch to be a lining layer, obtaining at least one response data based on the result, and finally obtaining an equivalent simulation feasibility result. Therefore, the problems of simplified blasting load model, incomplete ground stress unloading mechanism, low simulation efficiency of a composite support system, strong subjectivity of rock mechanical parameters and the like in the related technology are solved, the numerical simulation of the 'blasting-unloading-support' mechanical behavior in the large-section tunnel drilling and blasting construction process is realized, and theoretical tools and decision bases are provided for the fine and quantitative optimization design of the support scheme.

Inventors

ZHANG QI
DUAN RUJIAN
WU ZHIJUN
XU YOULIANG
LU HAIFENG
WANG CHUAN
LIU QUANSHENG

Assignees

武汉大学
中国水利水电第十四工程局有限公司

Dates

Publication Date: 20260512
Application Date: 20251208

Claims (5)

1. The tunnel blasting excavation and support equivalent simulation method based on three-dimensional finite difference is characterized by comprising the following steps of: Constructing a three-dimensional finite difference model, and determining surrounding rock parameters of the three-dimensional finite difference model; Calculating an equivalent peak load acting on an excavation profile surface, determining a time-course form of blasting load according to the surrounding rock parameters, and obtaining an exponential stress time-course load according to the equivalent peak load and the time-course form of blasting load; Based on the exponential stress time course load, performing coupling simulation of ground stress transient unloading to obtain a simulation result, performing equivalent treatment on an anchor rod support area to obtain the thickness of a reinforcing ring, and performing equivalent treatment on the combined action of sprayed concrete and a steel arch to obtain a lining layer; and based on the simulation result, the thickness of the reinforcing ring and the lining layer, acquiring at least one response data of the surrounding rock according to the three-dimensional finite difference model, and acquiring an equivalent simulation feasibility result according to the at least one response data.
2. The method of claim 1, wherein said constructing a three-dimensional finite difference model comprises: Acquiring a section geometric parameter and an engineering geological parameter of a target tunnel; based on the section geometric parameters and the engineering geological parameters, carrying out three-dimensional geometric modeling to obtain the three-dimensional finite difference model; And acquiring a geological strength index and a disturbance factor, and determining surrounding rock parameters of the three-dimensional finite difference model according to the geological strength index and the disturbance factor.
3. The method of claim 1, wherein said calculating an equivalent peak load acting on the excavated contoured surface comprises: Calculating the peak load generated by single-hole blasting on the wall of the gun hole; calculating equivalent blasting peak load of the slitting section based on the peak load generated by the single-hole blasting on the wall of the blast hole; and calculating the excavation profile radius of the target tunnel, and obtaining the equivalent peak load according to the equivalent blasting peak load of the cut segment and the excavation profile radius.
4. A method according to claim 3, wherein the equivalent peak load is: ; ; ; Wherein, the Is the equivalent peak load; For the equivalent blast peak load; The radius coefficient is equivalent excavation radius coefficient; for the radius of the tunnel excavation outline, a non-circular excavation surface can be obtained through conversion according to the equivalent area; The non-circular excavation surface can be obtained by conversion according to the equivalent area for the radius of the equivalent elastic boundary; Is the stress attenuation index; Is the poisson's ratio of the rock.
5. The method of claim 1, wherein the reinforcement ring has a thickness of: ; Wherein, the Is the thickness of the reinforcing ring; radius of the tunnel excavation profile; Is the length of the anchor rod; the number of the anchor rods is the number of the anchor rods on the tunnel section.

Description

Tunnel blasting excavation and support equivalent simulation method based on three-dimensional finite difference Technical Field The application relates to the technical field of numerical simulation of tunnels and underground engineering, in particular to a three-dimensional finite difference-based equivalent simulation method for tunnel blasting excavation and support. Background The extension of the traffic network in China to the western mountain area makes the large-section soft rock tunnel engineering become normal. In particular, soft rock, such as weathered sandstone, slate, has inherent characteristics of low strength, large deformation, significant rheology, poor self-stabilization capability, and the like. In the construction of a drilling and blasting method, the stability of surrounding rock faces three challenges, namely firstly, the rock mass is instantaneously disturbed by strong power load generated by blasting, so that original cracks are expanded and new damage is generated, secondly, the original ground stress balance is broken through by excavation, stress redistribution is caused by the stress balance, the unloading process shows remarkable transient characteristics under the blasting effect rather than quasi-static process, thirdly, soft rock shows remarkable rheological characteristics after unloading, and is mutually coupled with blasting power damage to form a complex mechanical process of power damage-aging deformation, so that the deformation of the surrounding rock often exceeds a design predicted value based on static theory, and cracking, torsion and even collapse of a supporting structure are caused. At present, numerical simulation research aiming at the problem has obvious defects that (1) a blasting load model is too simplified, the simulation in the related technology generally simplifies the blasting load into triangular waves or evenly distributed static force released instantly, the exponential time course characteristics of a continuous attenuation section of an actual blasting stress wave rising section can not be accurately reflected, and the dynamic weakening effect on surrounding rock mechanical parameters can not be accurately reflected, so that the prediction of the initial stage of severe deformation after excavation is severely distorted. (2) The ground stress unloading mechanism is considered to be incomplete, most methods in the related art ignore or simplify the transient unloading process of the ground stress in blasting excavation and the coupling effect of the transient unloading process and blasting power disturbance, and fail to truly restore the complex stress path change of surrounding rock in a very short time. (3) The simulation efficiency of the composite support system is low, namely for the anchor rod-shotcrete-steel arch combined support system widely adopted in engineering, if structural units such as cable, shell, beam are adopted in FLAC3D for fine modeling, the stress mechanism can be better reflected, but the model is extremely complex, the number of units is greatly increased, the calculation time is long, and the composite support system is difficult to be suitable for rapid inversion analysis and multi-scheme dynamic optimization in the construction stage. (4) The rock mechanical parameter determination is strong in subjectivity, namely the Hoek-Brown constitutive model for representing the nonlinear mechanical behavior of the soft rock in the related technology has the advantages that the values of the core parameter geological strength index (Geological Strength Index, GSI) and the disturbance factor (Disturbance Factor, D) are highly dependent on the experience judgment of engineers, an objective and quantitative determination method is lacked, and the reliability of the input parameters of the model and the credibility of the simulation result are directly influenced. Disclosure of Invention The application provides a three-dimensional finite difference-based equivalent simulation method for blasting excavation and support of a tunnel, which aims to solve the problems of simplified blasting load model, incomplete ground stress unloading mechanism, low simulation efficiency of a composite support system, strong subjectivity of rock mechanical parameters and the like in the related technology, realize numerical simulation of blasting-unloading-support mechanical behaviors in the drilling and blasting construction process of a large-section tunnel, and provide theoretical tools and decision basis for the fine and quantitative optimization design of a support scheme. The embodiment of the application provides a three-dimensional finite difference-based tunnel blasting excavation and support equivalent simulation method, which comprises the following steps of: Constructing a three-dimensional finite difference model, and determining surrounding rock parameters of the three-dimensional finite difference model; Calculating an equivalent pe