含水率及围压对砂岩蠕变特性影响的试验研究

Experimental study of the influence of moisture content and confining pressure on sandstone creep characteristics

在荷载作用下,岩石不仅表现出弹性和塑性,而且具有与时间相关的性质,即岩石的流变性。工程实践中,岩石流变现象随处可见,岩石流变所造成的危害也不容忽视。但目前在岩石含水率及围压对其流变特性影响研究仍不完善。本文采用岩石三轴压缩流变仪开展了不同含水率及围压条件下的砂岩压缩蠕变试验。试验发现,围压越大,砂岩的蠕变量越小;但当围压达到一定值后,围压对蠕变量的影响降低;砂岩含水率越高,瞬时应变越大,破坏时应变越大,长期强度越低;瞬时应变和破坏时应变均与含水率呈线性关系,长期强度与含水率呈负指数关系。

Under the action of load,rocks not only show elasticity and plasticity,but also have the time-depending properties,i.e.rock rheology.In engineering practice,rock rheological phenomena can be seen everywhere,and the damage caused by rock rheology can′t be ignored.However,the influence of moisture content and confining pressure on rheological properties of rock is still studied incomplete.Compressive creep experiment of sandstone was carried out,under condition of different moisture content and confining pressure based on a tri-axial compression rheological test apparatus.Experimental results show that the larger the confining pressure is,the smaller the sandstone creep value is.But when the confining pressure reaches a certain range,its influence on creep deformation reduces.The higher the moisture content is,the larger the instantaneous strain and failure strain becomes,and the lower the long-term strength gets.The instantaneous strain and failure strain are linearly related to moisture content;the long-term strength is negatively exponential with moisture content.