基于突变理论深埋硬岩隧道的失稳分析

在分析隧道开挖引起围岩扰动和损伤的基础上,运用突变理论探讨了深埋硬岩隧道失稳的机理;基于势能原理,建立了深埋硬岩隧道失稳的尖点突变模型,导出了失稳的力学判据条件。结果表明:深埋硬岩隧道的失稳不仅受岩体特性及所受载荷的影响,而且与围岩中弹性区刚度和塑性区刚度的比值有关;开挖过程中,围岩受扰动和损伤程度越大,岩体完整性系数越小,力学参数指标弱化程度越高,塑性区范围越大,刚度比越小,围岩系统发生失稳的可能性就越大。工程实例分析表明,分析结果与实际经验基本一致;研究成果可为预防隧道失稳、采取合理的施工工艺和支护措施提供参考依据。

INSTABILITY ANALYSIS OF DEEP-BURIED TUNNELS WITH CATASTROPHE THEORY

Based on the disturbance and damage analysis of tunnels surrounding rock due to excavation,the mechanism of instability of deep-buried hardrock tunnels is examined with catastrophe theory.Based on the potential energy principle,the cusp catastrophe model of instability of deep-buried hardrock tunnels is established.The mechanical criterions of instability are educed.Results show that the instability of deep-buried hardrock tunnels is not only influenced by rock mass characters and loads,but also related with the ratio of the stiffness of elastic regions over the stiffness of plastic regions.During excavation,the more serious the degree of disturbance and damage of surrounding rock,the less the integrity factor of rock mass,the higher the degree of softening of mechanical index,the larger the range of plastic regions,and the less the stiffness ratio,the more possible the instability of surrounding rock system.The analysis of an actual case shows that the analytical results are accordance to the practical experience.The present results can offer references for preventing instability and damage of tunnels,taking reasonable construction technique and supporting measurements.