红砂岩短时蠕变声发射b值特征

Study on b-value characteristics of acoustic emission of red sandstone during short-time creep process

岩石的蠕变性质是引起岩石破坏的原因之一。因此,对岩石蠕变破坏进行预测具有重要的意义。通过进行分级加卸载条件下的短时蠕变试验,研究了红砂岩在减速蠕变、等速蠕变与加速蠕变阶段的声发射b值特征。试验结果表明:试件在体积变形状态下,声发射b值在减速蠕变阶段与等速蠕变阶段随着蠕变时间的增大而增大;当试件处于体积不变状态与扩容状态下,声发射b值在等速蠕变阶段总体保持稳定;在加速蠕变阶段,声发射b值呈现出先减小,而后增大,最后再次减小的特征。因此,根据声发射b值在不同蠕变阶段的变化特征,在一定程度上可对红砂岩石蠕变破坏进行预测。

The creep property is one of the most important factors that affect rock failure. Therefore,it is necessary to forecast rock creep failure. The creep tests on red sandstone were carried out using step loading and unloading method,and the characteristics of b-value acoustic emission were analyzed during the primary creep stage,the steady state creep stage,and the tertiary stage. The results show that the b-value increases in primary creep stage and steady state creep stage as the specimens are in volumetric deformation state,and keeps stable in steady state stage as the specimens are in both constant volume and dilatancy state. When the specimens step into tertiary creep stage,the b-value firstly takes on a declining trend,and then increases with time increasing,and finally declines again before the specimen failure. Therefore,the red sandstone creep failure can be forecasted by the variation characteristics of b-value to some extent.