辉绿岩瞬态卸压下强度及变形特性数值模拟

Numerical Simulation of Strength and Deformation Characteristics of Diabase Under Transient Unloading

为探讨深部高应力脆性岩体爆破开挖瞬态卸压过程的强度、变形等力学特性,利用三维离散元程序的Mohr-Coulomb应变软化关系建立辉绿岩真三轴应力数值模型。在计算5组应力状态(σ2,σ3)岩样的三轴强度基础上,开展了恒定σ2卸压时间分别为2.5ms(卸压模式1)和250ms(卸压模式2)的峰前卸侧压σ3的数值模拟实验。模拟研究结果表明:1)岩样卸压极限强度较三轴抗压强度低,且等于峰前卸侧压值,说明卸压破坏应力小于加载破坏应力;2)卸压模式1实验应力跌落与应变突跳立刻发生,无滞后性;3)相同应力状态下,卸压模式1实验的应变改变量Δε3普遍较大;4)应力和应变的改变在卸压模式1实验过程中几乎不受卸压速率的影响。

In order to explore strength and deformation characteristics of deep high stress state of brittle rock mass during blasting excavation unloading transient process, diabase true triaxial stress state numerical model is set up by Mo- hr-Coulomb strain softening model of three-dimensional discrete element program. Unloading time by 2.5 ms and 250 ms pro-peak unloading lateral pressure σ3 numerical simulation test are conducted after triaxial compressive strength of five principle stress states（σ2 ,σ3 ） are calculated, which process keep σ2 as a constant. Simulation results show that： 1） Unloa- ding ultimate strength is lower than the triaxial compressive strength and the value is equal to pro-peak unloading lateral pressure value, explain that unloading damage stress is less than the loading damage stress; 2） Stress drop and deforma- tion sudden jump are immediately occurred which without delay under the unload pressure model 1 experiment; 3） The strain variation △ε3 generally larger of the unload pressure model 1 experiment under the same stress state; 4） These change of stress and strain are almost not affected by unloading rate under the unload pressure model 1 experiment.