基于常规三轴试验的岩石双剪强度准则

TWIN SHEAR STRENGTH CRITERIA FOR ROCR BASED ON TRADITIONAL TRIAXIAL TESTING RESULTS

基于岩土体的双剪强度理论和已有的一些岩石真三轴强度试验资料,提出了一个岩石双剪强度准则的推广型式,探讨了该强度准则相关参数的选取问题,验证了该强度准则的合理性,并指出双剪强度准则有一个)()(8mfgsqts=的函数表达型式。研究表明岩石的tc88/tt随平均主应力ms的变化而变化,当ms较小时tc88/tt比值较大,而当ms较大时tc88/tt比值较小。这种现象一方面论证了随着ms的增大,岩石有逐步向着均质化方向发展的趋势;另一方面也说明了在较低的ms应力水平下,Drucker-Prager强度准则对岩石类材料是不适合的。

Based on twin shear strength theory and some true triaxial strength testing data of rock, a more reasonable twin shear strength criterion is proposed and verified. The corresponding parameters of the twin shear strength criterion are given by traditional triaxial compressive and triaxial tensile testing results. It is shown that the twin shear strength criterion has a 8t=)(sqg)(mfs function expression, and the calculating results in this paper show that tc88/tt will be changed as the average principal stress ms is changed. tc88/tt is larger when ms is at lower stress level, and is smaller when ms is at higher stress level. This phenomenon demonstrates on one side that rock is developed into homogeneous material gradually as ms is increased, on the other side that the Drucker-Prager strength criterion is not suitable for rock materials when ms is at lower stress level.