不同粒径砂岩力学特性试验研究

Experimental study on mechanical properties of sandstone with different granularities

为探究不同粒径砂岩长短期力学行为的差异,对取自某水电建设工程现场的粗、中、细三种粒径大小的砂岩进行了短期三轴压缩、三轴渗透以及蠕变力学试验.研究表明：相同围压下,粒径越大的砂岩,其强度、粘聚力及变形量越小;同等粒径下,长短期强度值及变形量随着围压升高呈线性增加;砂岩的渗透率在屈服阶段快速增加并在破坏前后达到最大值,粒径越大的砂岩,其渗透性越强;相同偏应力和围压下,砂岩的稳态蠕变速率随着粒径增大而减小;同等粒径和围压下,稳态蠕变速率随着偏应力增加而呈指数型函数增长;同等粒径和偏应力下,围压越大,其稳态蠕变速率越低;三种粒径砂岩在长期荷载作用下对应的强度较短期值下降了40%~60%,内摩擦角和内聚力则分别较短期值降低了40%和40%~50%,其中,中砂岩下降幅度最大.

In order to inxestigate and rexeal the influence of granularity on mechanical behaxior in the short and long term load,the conxentional and creep test are conducted on coarse sand stone,medium sandstone and fine sandstone of a pro-ject. The results shows that：the strength and deformation capacity increase with the decrease of granularity under the same confining pressure;the strength,deformation and elastic modulus increase linearly with the confining pressure increasing un-der the same size;the steady creep rate decreases with the grain of sandstone size under the same size and confining pres-sure;steady creep rate with partial stress increased exponential function growth under the same dexiator stress and confining stress;steady creep rate is smaller with the confining pressure increasing under the same size and partial stress;three kinds of particle size of sandstone under long-term load corresponding strength than short-term xalue decreased by 40% ~60%;the internal friction angle and cohesion are compared with the short-term xalue reduced by 40% and 40% ~50%.