基于围压增量的损伤砂岩三轴蠕变试验

为研究岩石峰后轴向与径向蠕变特性,采用MTS815岩石力学试验系统,进行了三轴压缩下红砂岩峰后蠕变试验,获取了不同性态的峰后轴向与径向蠕变曲线,探讨了岩石峰后轴向与径向蠕变特征,研究了损伤程度、围压增量对峰后轴向与径向蠕变特性的影响规律.试验结果表明:岩石峰后轴向与径向蠕变曲线主要由等速蠕变阶段和加速蠕变阶段组成,峰后径向蠕变特征相比轴向蠕变特征更显著;轴向和径向蠕变量与损伤程度呈正相关,径向蠕变相比轴向蠕变对损伤程度的敏感性更高,损伤程度的变化对径向蠕变的影响程度更强;施加围压增量,轴向与径向蠕变速率大大降低,蠕变失稳时间延长;围压增量对径向蠕变的影响明显强于轴向蠕变,工程实践中应重点控制围岩的径向变形.

Experimental study on triaxial creep of damaged sandstone based onconfining pressure increment

In order to study the axial and radial creep characteristics of rock post-peak, creep test of red sandstone post-peak under uniaxial compression was carried out to obtain the axial and radial creep curves of different states of rock post-peak, the axial and radial creep features of rock post-peak were discussed ,by using MTS815 rock mechanics test system, the influence regular pattern of the damage degree was researched, and confining pressure increment on the axial and radial creep characteristics of rock post-peak were discussed. The experimental results show that the axial and radial creep curves of rock post-peak are mainly formed by the constant creep stage and the accelerated creep stage, the radial creep has a more obvious characteristic than the axial creep feature.The amount of the axial and radial strain is positively correlated with the damage degree, and the radial creep is more sensitive to the damage degree than axial creep.With Exerting the confining pressure increment,the axial and radial creep rate is greatly reduced and the creep instability time is prolonged.The effect of confining pressure increment on radial creep is stronger than that of axial creep,and the radial deformation of surrounding rock should be focused on controlling in engineering practice.