中文摘要：

为了更准确认识坝基岩体中的软弱夹层剪切蠕变特性,进行不同正应力水平下的剪切蠕变试验,采用不同正应力水平下分级加载剪应力的方式,重点研究软弱夹层的剪切蠕变变形规律、破裂机制及其长期抗剪强度。研究结果表明,经验公式u=u0+A[1-exp(-Bt)]Ctn能较好反映软弱夹层的剪切蠕变变形规律,不同正应力水平下的平均及稳态剪切蠕变速率随剪应力增加呈指数函数增大,且软弱夹层剪切蠕变破坏呈现典型的延性破坏特征。通过新提出的拐点法确定不同正应力水平下的长期抗剪强度,并与稳态速率法的计算结果进行对比,验证了拐点法的合理性和适用性,该方法大大提高了确定岩体长期抗剪强度的准确性,对工程实际具有重要的参考价值。

英文摘要：

In order to understand exactly the creep property of weak intercalation in dam foundation rock,the shear creep test is carried out under different normal stresses by using step loading shear stress. The shear creep deformation law,failure mechanism and long-term shear strength of weak intercalation are concerned in this study. The results indicate that the empirical formulation u=u0+A[1-exp(-Bt)]+Ctn can reflect the shear creep deformation law of weak intercalation properly,the average and steady-state shear creep rates increase at a exponential function with the shear stress increasing,and the shear creep failure of weak intercalation shows typical ductility failure characteristics. Based on a new method,called inflection-point method,the long-term shear strength of weak intercalation under different normal stresses is determined. The calculation results of inflection-point method are compared with that of steady-state rate method,and the rationality and validity of inflection-point method are test. The research results show that this method greatly improves the accuracy of determining the rock mass long-term shear strength and brings important reference for engineering practice.