基于Hoek-Brown准则的冻融循环条件下露天煤矿边坡岩体力学系数修正

在露天矿边坡稳定性计算和评价过程中，边坡稳定性评价结果与岩体力学参数的选取密切相关。而在冻融循环条件下，岩石的物理力学参数随着冻融次数的变化而变化。首先通过室内模拟的方法对粗砂岩和细砂岩进行不同次数的冻融循环试验，然后进行一系列的单轴和三轴压缩试验，得到冻融循环条件下完整粗砂岩和细砂岩的物理力学参数；基于Hoek-Brown强度准则中的爆破扰动参数D，提出冻融循环劣化参数D_f，利用修正的Hoek-Brown准则得到冻融循环条件下岩体力学参数，并分析了边坡岩体的破坏模式。结果表明:随着冻融循环次数的增加，粗砂岩和细砂岩的单轴抗压强度、弹性模量和黏聚力降低减小，内摩擦角变化较小；而岩体的单轴抗压强度、整体抗压强度、抗拉强度、变形模量、黏聚力和内摩擦角均减小，这说明岩体在冻融循环环境中是不断损伤的，质量逐渐变差；随着冻融循环次数不断增加，岩体的抗剪强度劣化在不断加速，边坡的破坏形式主要为剪切破坏。修正的岩体力学参数为露天矿边坡稳定性分析提供更为准确的数据。 

Hoek-Brown criterion-based modification of the mechanical parameters of rock mass of open pit slope under freezing-thawing cycle

The results of slope stability are closely related with the selection of mechanical parameters of rock mass in the process of open-pit slope stability calculation and evaluation. With the increase of freezing-thawing cycles, the physical and mechanical characteristics of rock change under freezing-thawing condition. Based on experimental research on simulating natural conditions of Tibetan area, two kinds of sandstone samples were collected from different freezing-thawing cycles, then a series of uniaxial and triaxial compression tests were conducted after different freezing-thawing cycles (0, 30, 60, 90, 120 times), the physical and mechanical characteristics of sandstone were obtained. Based on the disturbance parameter D, the freezing-thawing deterioration parameter D_f was proposed. Based on the modified Hoek-brown strength criterion, the mechanical parameters of the rock mass were obtained after different freeze-thaw cycles. The failure mode of rock slope was analyzed. The results showed that with the increase of the number of freezing-thawing cycles, uniaxial compressive strength, elastic modulus and cohesion decreased, the internal friction angle changed little. However, the uniaxial compressive strength, tensile strength, the global strength, modulus of deformation, cohesion and internal friction angle of rock mass decreased; the failure form of the open-pit slope under freeze-thaw condition are shear failure. The modified rock mechanical parameters provide more accurate data for slope stability analysis of open pit.