超前核心土加固对隧道围岩变形规律的影响分析

Influence Analysis of Advanced Core Soil Reinforcement on Deformation Law of Tunnel Surrounding Rock

随着我国交通运输领域的发展,长大软岩隧道数量激增,故保证软岩隧道的整体稳定性对于高速公路、铁路的发展具有重要意义。从岩土控制变形分析法的核心思想出发,使用有限差分数值软件,考虑不同围岩级别、不同地应力条件、不同超前核心土加固强度及加固长度、不同洞身支护刚度进行全断面开挖数值模拟,得出以下结论:(1)在软弱围岩条件下,超前核心土加固强度越大,控制变形效果越好,但当强度提高到一定程度时,控制效果逐渐弱化,故合理地确定超前核心土的加固强度对于控制围岩变形具有重要意义;(2)超前核心土加固长度越长,围岩变形的控制效果越好,但随着加固长度的增大,对位移控制效果逐渐弱化,故建议取0.5倍隧道洞径内进行超前核心土加固;(3)在软弱围岩情况下,洞身支护刚度的增大,会对掌子面及洞身收敛变形控制有明显效果。研究成果可为相关类似隧道工程的安全修建提供理论参考。

With the development of Chinese transportation field,the number of long soft rock tunnels has become prominent.Ensuring the overall stability of soft rock tunnels is of great significance to the development of expressways.Starting from the core idea of rock and soil control deformation analysis method,using finite difference numerical software,considering different levels of surrounding rock,different in-situ stress conditions,different reinforcement strength and length of advanced core soil,and different supporting stiffness of tunnel body,the full section excavation numerical simulation is carried out.Following conclusions are drawn:(1)In the case of soft surrounding rock,the strengthening strength of advanced core soil is stronger,the better deformation control effect will be.However,when the strength increases to a certain degree,the control effect will gradually weaken.Therefore,it is of great significance to reasonably determine the strengthening strength of advanced core soil to control the deformation of surrounding rock;(2)The strengthening length of advanced core soil is longer,the better deformation control effect will be,but the control effect of displacement is gradually weakened with the increase of the reinforcement length.Therefore,it is suggested that it is more appropriate to carry out the reinforcement with the reinforcement length 0.5 times of the tunnel diameter;(3)In the case of soft surrounding rock,the increase of the supporting stiffness of the tunnel body will have obvious effect on the convergence deformation control of the tunnel face and the tunnel body.The research results can provide theoretical reference for the safety construction of related similar tunnel projects.