有限元强度折减法在隧道施工稳定分析与控制中的应用

Application of FEM Strength Reduction Method in Stability Analysis and Control of Tunnel Construction

有限元强度折减法广泛应用于边坡等工程的稳定分析中,而在隧道工程稳定分析中的应用相对较少。文章将有限元强度折减法用于隧道施工稳定分析与控制中,提出基于围岩安全系数进行施工阶段围岩稳定性全过程的动态评价,并通过隧道洞周围岩变形规律的研究,建立施工阶段隧道监控量测的动态控制指标。通过算例分析可以看出,基于围岩安全系数可以定量、直观地掌握整个施工阶段围岩稳定性的动态演化规律;在满足初期支护施作后围岩稳定性要求的前提下,可以针对各个施工阶段建立相应的变形控制指标,从而克服以围岩容许位移作为隧道稳定性判断依据的局限性。通过有限元强度折减法在隧道施工稳定分析与控制中的应用,将为解决隧道施工安全问题提供新的途径。

FEM strength reduction method has been more widely used in the stability analysis of slope engineering rather than tunnel engineering.In this paper the FEM strength reduction method is adopted in a stability analysis and control of tunnel engineering,and a dynamic evaluation on the surrounding rock stability in whole construction process is proposed based on the safety factor.The dynamic controlling indexes of tunnel monitoring and measure⁃ment during construction are established by studying the deformation law of tunnel surrounding rocks.The analysis on calculation examples show that the dynamic evolution law of surrounding rock stability during construction can be mastered quantitatively and visually based on the safety factors of rock mass;the corresponding deformation con⁃trol indexes can be determined for different construction stages under premise of meeting the stability requirements of surrounding rocks after installing primary support so as to overcome the limitation of taking the permissible dis⁃placement of surrounding rocks as the criteria of tunnel stability.