软岩黏弹塑性流变特性及非线性蠕变模型

Visco-Plastic Rheological Properties and a Nonlinear Creep Model of Soft Rocks

采用分级增量循环加卸栽方式，对金川有色金属公司Ⅲ矿区软弱矿岩进行流变试验，探讨了软弱矿岩的黏弹塑性变形特性．建立了软岩的非线性蠕变模型．结果表明：分级增量循环加卸载下软岩有明显的瞬时应变硬化趋势，软弱矿岩JC1099试件的黏弹性应变分量与黏塑性应变分量之比为3．15～6．58，随应力水平的增加蠕应变中黏塑性应变占的份量总体上有增加走势；在低应力水平下，蠕变变形趋于稳定状态，在高应力水平下，软岩蠕变往往表现出加速蠕变特性．建立的非线性蠕变模型可以用统一的蠕变方程来描述软岩蠕变的3阶段，将该模型应用于金川Ⅲ矿区矿岩蠕变试验，蠕变试验曲线与理论曲线较为吻合．

A set of creep experiments was performed to study the viscoelastic behavior of soft ore-rock from the Jinchuan Mine Ⅲ under cyclical loading. A nonlinear creep model of the soft rocks was established. The results show that the instantaneous deformation modulus increases with increasing creep stress; Softer rocks have an enhanced ability to resist instantaneous elastic and plastic deformation during the step-loading and unloading in the cyclic process. The JC1099 specimen shows a ratio of visco-elastic strain to visco-plastic strain that varied from 3. 15 to 6.58. The ratio tended to decrease as the stress increased and creep deformation tends toward a steady state at low stress levels. Soft-rock-creep usually involves an accelerated creep at high stress levels. The nonlinear creep model can describe the three stages of soft rocks creep with a single expression. This model applied to the creep experiments on the ore-rock of the Jinchuan Mine Ⅲ makes predictions that are in good agreement with the experimental data.