地震作用下水平层状岩质边坡累积损伤与破坏模式研究

Study of cumulative damage and failure mode of horizontal layered rock slope subjected to seismic loads

研究边坡在反复地震作用下的累积损伤对于库区岩质边坡的长期稳定性分析具有重要意义。结合振动台试验与理论分析方法,对水平层状岩质边坡在反复地震作用下的累积损伤与破坏模式进行了深入研究。结果表明:采用混凝土疲劳裂纹扩展的双K准则可以很好地解释边坡的累积损伤曲线的变化趋势,完整的累积损伤演化曲线表现出初始损伤、细观裂纹扩展、宏观裂缝扩展3个阶段;分别采用三次多项式和幂指数建立了微小地震和强震作用下边坡岩体累积损伤演化模型并取得了良好的拟合效果,微小地震作用下边坡岩体累积损伤曲线表现出初期略微下降、中期线性增长、后期平缓增长的正"S"型的3段式特征,强震作用下边坡岩体累积损伤相比微震作用下有较为快速的增长,且在边坡破坏前增速加快。频发微震作用下,水平层状岩质边坡在坡体上部形成阶梯型破坏面并向坡面出露,在坡体下部形成平直的剪切破坏面,坡体最终的破坏面呈阶梯状。

It is of great practical significance to study the cumulative damage of slope under repeated seismic loads for long-term stability analysis of rock slope in reservoir area. In this paper, shaking table test and theoretical analysis were used to study the cumulative damage and failure mode of horizontal layered rock slope under repeated seismic loads. Results show that the fatigue crack propagation of concrete double K criterion explains the change tendency of the slope of the cumulative damage curve well. The complete cumulative damage evolution curve shows three stages, i.e., the initial damage stage, mesoscopic crack extension stage and macroscopic crack extension stage. The well fitted cubic polynomial and power exponent are adopted to establish the cumulative damage evolution model of slope rock mass under the action of micro-small earthquakes and strong earthquakes respectively. The cumulative damage curve of slope rock mass shows slight dip in the early stage, linear growth in the middle stage and moderate growth in the last stage under the action of micro-small earthquakes, which has the features of the positive "S" type. And the cumulative damage of slope rock mass under the action of strong earthquakes has a relatively rapid growth compared with that under the action of micro-small earthquakes, and the increase rate of which is accelerated before the slope failure. Under the action of frequent micro earthquake, stepped failure surfaces on the upper part of the horizontal layered rock slope are formed and exposed to the slope surface, while straight shear failure surface if formed on the lower part of the slope. The final failure surface of the slope is a stepped one.