隧洞围岩空间随机分布特性对隧洞稳定性的影响研究

Study of Effect of Spatial Stochastic Distribution of Surrounding Rocks on Tunnel Stability

根据分水江隧洞围岩强度的空间随机分布特征,采用蒙特卡罗随机有限元方法分析了扰动区围岩强度空间随机分布条件下隧洞开挖后围岩扰动区最大等效应力、最大拱顶位移、收敛变形、仰拱隆起的概率分布规律.并采用Ansys中concrete损伤本构模型,分析了扰动区围岩强度平均值相同但离散程度不同时扰动区裂纹分布范围变化规律,建立了考虑隧洞围岩空间随机性的隧洞开挖稳定性概率设计方法.结果显示:围岩强度空间随机分布离散程度越大(强度的标准差从0.608增大至1.216),围岩稳定性越差,裂纹分布范围越广(从1.7m增加至6m),注浆加固范围应增大.研究方法为设计更科学的支护体系提供了理论基础.

According to the stochastic spatial distribution of surrounding rocks in the disturbed area of Fen- shui River Tunnel, the Monte Carlo method is used to analyze the stochastic distribution characteristics, i. e the maximum equivalent stress, the maximum vault displacement, the convergence deformation and the In- verted arch uplift of the surrounding rock disturbance area after the excavation of the tunnel under the condi- tion of considering stochastic spatial distribution of surrounding rocks . When the average intensity of sur- rounding rocks is same, but the stochastic spatial distributionare different in the disturbed area, analyzing the change of the crack distribution range in the surrounding rocks by using the concrete damage constitutive model in Ansys . The probability design method of excavation stability of tunnel surrounding rock is put for- ward under the condition of considering the stochastic spatial distribution of surrounding rocks. The results show that the greater the discreteness of the random distribution of surrounding rock is （the standard of sur- rounding rocks＂ intensity increase from 0. 608 to 1. 215）, the worse the stability of surrounding rock is; the wider distribution of crack is （from 1.7 meter to 6 meter）, and the grouting range should be increased. The research methods proposed in this paper provide a more scientific theoretical basis for the design of tunnel support system.