【摘要】 为量化不同围岩级别下大拱脚暗挖车站隧道的稳定储备与变形响应，文章采用强度折减法与尖点突变理论，通过塑性应变增量突变识别临界折减系数，并等效确定隧道剪切安全系数。结果表明，围岩由完整向破碎软弱演化时，剪切安全系数单调降低；Ⅰ级、Ⅱ级和Ⅲ 1级围岩安全系数均大于5,Ⅲ 2、Ⅳ 1、Ⅳ 2、Ⅳ 3、Ⅴ 1级分别为4.09、3.40、2.70、2.08和1.00。临界折减附近，变形与塑性演化同步突变，位移和塑性集中区主要位于侧墙，Ⅳ级及以下围岩进一步在侧墙与脚趾下部形成耦合高敏区。研究证实，该联合判据可有效识别隧道由渐进变形向失稳演化的转折点，为软弱围岩条件下加固设计与监测布置提供依据。更多还原

【Abstract】 To quantify the stability reserve and deformation response of a large arch-foot mined station tunnel under varying surrounding rock grades, the strength reduction method and cusp catastrophe method are used. The critical reduction factor is identified from abrupt plastic strain increment and converted into shear safety factor. Results show that the shear safety factor decreases as rock grade deteriorates from complete to fragmented. Safety factors for the surrounding rocks of Grades Ⅰ, Ⅱ and Ⅲ all exceed 5, and those for Ⅲ2, Ⅳ1, Ⅳ2, Ⅳ3, and Ⅴ1 are 4.09, 3.40, 2.70, 2.08, and 1.00, respectively. Near the critical state, deformation and plastic evolution change synchronously, with displacement and plastic zones mainly in sidewalls. For the surrounding rocks of Grade Ⅳ and below, a coupled highly sensitive zone further develops in sidewalls and beneath the arch foot. The proposed criterion effectively identifies the transition from progressive deformation to instability, providing basis for the reinforcement design and monitoring arrangement in weak surrounding rocks.更多还原