加载速率和围压对煤能量演化影响试验研究

Experimental research on influence of loading rate and confining pressure on energy evolution of coal

借助TAW-2000型电液伺服岩石力学试验系统进行了不同加载速率和不同围压下煤样的单轴压缩和三轴压缩试验,研究了加载速率和围压对煤样能量耗散特征的影响规律,探讨了煤样耗散应变能转化速率随加载速率和围压的变化规律。研究表明:单轴压缩试验第Ⅰ阶段试件的弹性应变能随加载速率的增加呈现先增大后减小的特点,耗散应变能转化速率均处于较低水平,且与加载速率呈负相关,第Ⅱ阶段耗散应变能随加载速率的增加也呈先增大后减小的趋势,各煤样耗散应变能转化速率的最大值均出现在峰值点或峰后轴向应力陡然跌落点。耗散应变能转化速率对围压十分敏感,围压越大,耗散应变能的转化速率也越大,煤样变形损伤越快。

A serial of uniaxial and triaxial compression tests on coal samples under different loading rates and confining pressures are conducted by using the TAW-2000 electro-hydraulic servo system. The characteristics of energy dissipation of coal under different loading rates and confining pressures are studied, and the dissipation strain energy conversion rate is also discussed. The results show that the elastic strain energy increases at first and then decreases at stage I of the uniaxial compression tests, and the dissipation strain energy conversion rate, which has a negative correlation with the loading rate, is relatively low. At stage II, the dissipation strain energy increases at first and then decreases with the increasing loading rate. The maximum strain energy dissipation conversion rate occurrs at the peak point or axial stress suddenly falling point after the peak point of stress-strain curve. The dissipation strain energy conversion rate is very sensitive to the confining pressure. That is, the larger the confining pressure, the greater the dissipation strain energy conversion rate, and the faster the damage of the coal.