软硬互层边坡岩体的蠕变特性研究及稳定性分析

岩体的蠕变性是影响边坡变形与长期稳定性的重要因素之一。以清江水布垭坝址区马崖高边坡为例，针对边坡内具代表性的软岩和硬岩，通过开展室内岩石压缩蠕变试验，研究了不同类型软、硬岩石的蠕变破坏特征，据此建立了岩石的流变本构模型并进行参数辨识。在此基础上，应用三维粘弹塑性方法对马崖高边坡的时效变形及稳定性进行数值分析，探讨了边坡在开挖卸荷及泄洪冲切（运行期）等工程荷载作用下岩体的蠕变变形及塑性区发展。研究结果表明，软硬互层边坡岩体的蠕变效应十分显著，对于大规模开挖的岩质高边坡而言，岩体的蠕变特征不仅影响到边坡的位移量值，而且改变了边坡的位移形态。在工程长期运行过程中，岩体蠕变引起的应力场变化使得坡体内塑性区分布由坡面向坡内延伸，按流变10a计，其延伸深度可达数十米。

STUDY ON CREEP BEHAVIOR OF ALTERNATIVELY DISTRIBUTED SOFT AND HARD ROCK LAYERS AND SLOPE STABILITY ANALYSIS

The time-dependent behavior of rock mass is one of the important factors that influence the deformation and long-term stability of the slope.As an engineering example,Maya high slope is studied,which is located at the Shuibuya dam site on the Qingjiang River,with alternatively distributed soft and hard rock layers.The creep failure characteristics of different soft/hard rocks are studied through laboratory compressive-creep tests.Then,the rock rheological constitutive model is established;and the parameters are identified accordingly.With these understandings,the time-dependent behavior and the stability of the Maya slope are analyzed by using 3D viscoelastic-plastic numerical method.The results show that the time-dependency effect is very remarkable.As for the high rock slope with large-scale excavations,the creep characteristics influence the quantity of the displacement and change its direction.In the long-term running process of the engineering,the changes of the stress field induced by the rock creep will cause the plastic zone to extend from slope surface to the inward;and the extending range could stretch dozens of meters for ten years.