冻融循环作用下倾倒式危岩体稳定性劣化模型

为了探究冻融作用对倾倒式危岩体稳定的作用机理及长期劣化规律， 基于极限平衡理论，考虑结构面冻胀力、未贯通段抗拉强度劣化及冻结深度演化对倾覆点力矩的影响，构建倾倒式危岩体稳定性分析方法. 基于岩石冻胀理论，考虑岩石碎屑流失、微裂隙倾角、温度等参数对孔隙半径冻胀破坏的影响，建立岩石抗拉强度劣化模型并验证其合理性. 利用裂隙分布不均性修正Stephan冻结深度经验公式，得到冻融循环作用下岩石冻结深度计算方法. 结合工程算例，讨论不同敏感参数对倾倒式危岩体稳定性的影响. 结果表明：初始抗拉强度越低、孔隙率越大，危岩体稳定性劣化效果越显著；当环境温度高于263.15 K (?10 ℃)时，危岩体稳定性对温度的变化敏感，危岩体保温措施的效果显著；当碎屑流失比超过0.8时，冻融循环作用对危岩体的劣化速率明显加快，倾倒式危岩体的长期冻融劣化效应明显，控制冻胀破坏产生的碎屑流失有利于寒区危岩体保持长期稳定.

Stability deterioration model of toppling unstable rock mass under freeze-thaw cycle

The action mechanism and long-term deterioration law of freezing and thawing on the stability of toppling unstable rock mass were explored. Firstly, based on the limit equilibrium theory, considering the influence of the frost heave force of the structural plane and the tensile strength, freezing depth of the non-through section on the moment of the overturning point, the analysis method of stability deterioration of toppling unstable rock mass was put forward. Secondly, based on the frost heave theory of rock, considering the influence of rock debris loss, different dip angles and temperature of microfissures on pore radius’ mechanical properties, the deterioration model of rock tensile strength was constructed. Thirdly, Based on the uneven distribution of cracks, the empirical formula of Stephan freezing depth was modified, and the calculation method of rock freezing depth under freeze-thaw cycle was obtained. Finally, combined with an engineering example, the influence of different sensitive parameters on toppling unstable rock mass stability was discussed. Results showed that the lower the initial tensile strength and the higher the porosity, the more obvious the deterioration effect of the stability of unstable rock mass. When the ambient temperature was higher than 263.15 K (?10 ℃), the stability of unstable rock mass was more sensitive to the change of temperature, and the effect of thermal insulation measures for unstable rock mass in this temperature range was more significant. When the debris loss ratio was more than 0.8, the deterioration rate of unstable rock mass caused by freeze-thaw cycle was obviously accelerated, and the control of debris loss caused by frost heave failure was more conducive to the long-term stability of unstable rock mass in cold regions.