“三段式”岩石滑坡的锁固段破坏模式及演化机制

锁固段的地质结构及力学性质是“三段式”岩石滑坡的关键控制因素。根据“三段式”滑坡的地质结构特征,采用物理模型试验和颗粒流数值模拟方法,研究了锁固段岩桥角（后缘拉裂隙与前缘蠕滑段末端连线和水平方向间的角度）对锁固段的破坏模式及演化机制的影响规律。锁固段破裂的模式主要有张拉贯通破坏和张-剪混合贯通破坏两种。随着锁固段岩桥角的增大,锁固段破坏模式由张拉破坏向张-剪混合破坏转变：岩桥角小于90°时,为张拉破坏;岩桥角位于90°~110°之间,为张-剪混合破坏;当岩桥角大于110°时,锁固段并不发生破坏,边坡以其它形式发生破坏。通过锁固段的应变时程分析,随着锁固段岩桥角增大,锁固段区域拉应力的影响范围逐渐减小,由全部受拉向全部受压转变。

Failure pattern and evolution mechanism of locking section in rock slope with three-section landslide mode

The geological structure and mechanical properties of locking section are the key control factors to the rock slope with three-section landslide mode. According to the characteristics of the geological structure of three-section landslide, physical model tests and particle flow numerical simulation method were used to study the influences of the angle of rock bridge of locking section (the angle between the line of the end of the tensile crack to the end of the creep section and the horizontal direction) on the failure mode and failure evolution of locking section in the rock slope with three-section landslide mode. The failure modes of the locking section can be summarized as tensile coalescence and mixed tensile-shear coalescence. With the increase of the angle of rock bridge of the locking section, the failure mode is changed from the tensile coalescence to the mixed tensile-shear one. When the angle is less than 90°, the failure of slope is caused by the tensile coalescence. When the angle is between 90°and 110°, the failure of slope is caused by the mixed tensile-shear coalescence. When the angle is greater than 110°, the failure occurs in other areas instead of the locking section. Based on the analysis of the strain-time curve of locking section, the tensile zone of the locking section decreases gradually with the increase of the angle of the rock bridge of the locking section, and its stress state is changed from the whole tension to the whole compression.