Dynamic stability analysis of bedding and toppling rock slopes under repeated micro-seismic action
摘要
The high-frequency and micro earthquake induced by the Three Gorges Reservoir after impoundment will have an important influence on the stability of the regional geological body to a certain extent. The shaking table tests and UDEC numerical analysis method are used to analyze the dynamic stability of the typical bedding and toppling rock slopes under repeated micro earthquakes. The results show that the acceleration response of the two types of slopes exhibits the "elevation effect" and "surface effect", and with the increase of earthquake action frequency, the slope damage (manifested as the initiation, expansion and penetration of structural plane and secondary rock joint) accumulates continuously and the dynamic response of the two types of slopes decreases. Under the repeated micro earthquakes, the decrease of the natural frequency of the slopes and the increase of the damping ratio are the basic laws of the dynamic characteristics. The permanent displacement increases with the increase of earthquake action frequency, and the stability coefficient decreases. Under the repeated micro earthquakes, the vertical tension cracks at the trailing edge of the bedding slope gradually extend and connect with substratum, and the slope is mainly caused by the overall slip instability along the joint surface. Block caving firstly appears at the slope shoulder and the slope surface in the toppling slope, subsequently, the upper strata are peeled off layer by layer, and finally a circular failure surface is formed. The main characteristics of the slope are rock fall at the slope shoulder and collapse of the middle and upper strata.