摘要
针对大安山煤矿+550水平西二石门围岩蠕变变形严重的问题,采用室内蠕变试验与理论分析相结合的方法研究岩石蠕变特性。选取泥质粉砂岩作为软岩试样,通过自制三轴蠕变仪对所取岩样进行恒围压分级增轴压的三轴压缩蠕变试验,结果表明:随应力水平的提高,起始蠕变速率增大,进入稳态蠕变阶段用时延长,稳态蠕变速率从0h-1增大到3.12e-4·h-1,瞬时应变以线性关系增加,围压9MPa条件下的起始蠕变应力阈值为6MPa,当应力水平超过岩石长期强度时出现加速蠕变。基于蠕变试验规律,考虑起始蠕变应力阈值,将一种可用阶跃函数表示的开关元件与广义K体并联,并引入损伤元件对CVISC蠕变模型进行改进。采用1st-Opt中的Levenberg-Marquardt+通用全局优化法计算蠕变参数并进行反演。反演结果表明理论曲线与试验曲线的吻合效果较好,证明了所建模型的合理性。上述研究成果可为岩石工程的长期稳定性分析提供试验和理论依据。
Aiming at the serious creep deformation of surrounding rock at ＋550m level west 2 cross- cut of Da＇anshan coal mine, indoor experimental study and theoretical analysis were adopted to study rock creep properties. Argillaceous siltstone was selected as soft rock specimen. Triaxial compression creep experiment of selected rock specimen was carried out by using home-made triaxial creep testing equipment under conditions of constant confining pressure and stage increase of axial pressure. Results show that along with the stress increase, the initial creep rate increases and the time to reach steady creep stage is extended; steady creep rate increases from 0 to 3.12e^-4 · h^-1; in addition, the instantaneous strain linearly increases; the initial creep stress threshold is 6MPa of argillaceous siltstone under 9MPa confining pressure, and creep acceleration appears when the stress level is higher than long-term strength. Based on creep experimental data and taking into account the initial creep stress threshold, a switching element, which can be expressed by step function, is parallel connected with a generalized K body, at the same time, a damage element is introduced to improve CVISC creep model. Adopting Levenberg-Marquardt plus general global optimization method of 1st-Opt to calculate the creep parameters and inversion. Results of inversion indicate that theoretical curve is in good agreement with experimental results, which demonstrates the model rationality. Above study achievements can provide experimental and theoretical references of long-term stability analysis for rock engineering project.
出处
《实验力学》
CSCD
北大核心
2015年第4期438-446,共9页
Journal of Experimental Mechanics
基金
国家自然科学基金青年科学基金项目(51404130)
(51204086)资助
