雨后不同时长基覆型边坡动力失稳破坏研究

Study on Dynamic Instability Failure of Base⁃covered Slope at Different Duration after Rainfall

基覆型边坡由于其上部为松散型堆积体,下部为基岩的特点,在降雨和地震作用下的失稳过程和破坏特征和其他边坡有较大不同,而降雨和地震作用的间隔时间会对二者耦合作用产生较大影响。利用自制的模型箱对基覆型边坡开展振动台模型试验,研究不同降雨停止时长对边坡稳定性的影响以及边坡降雨后静止不同时长在地震作用下的失稳特征和破坏模式。试验结果表明,降雨后间隔不同时间发生地震,边坡的破坏方式均呈过渡式破坏。在达到一定降雨强度后,降雨期间边坡含水率和孔隙水压力突增,而降雨停止后随着静止时长的增加,二者不断减小,之后达到稳定状态;随着静止时长的不断增加,基覆型边坡失稳临界加速度不断增加,大致和静止时长呈一个正相关的函数关系。

The instability failure process and characteristics of base-covered slopes,characterized by a loose upper deposit and underlying bedrock,differ significantly from other slopes under rainfall and seismic action.The time interval between rainfall and earthquake significantly affects their coupling ef-fect.Using a self-made model box,shaking table model tests were conducted on base-covered slopes to study the influence of different rainfall cessation durations on slope stability,as well as the instabili-ty characteristics and failure modes under seismic action after different stationary durations post-rain-fall.The test results showed that the failure mode of the slope exhibited transitional failure regardless of the time interval between rainfall and earthquake.After reaching a certain rainfall intensity,the soil moisture content and pore water pressure of the slope increased sharply during the rainfall,and de-creased continuously to a stable state with the increasing stationary duration after rainfall stopped.With the increase of the stationary duration,the critical acceleration of slope instability increased,showing a positive correlation with the stationary duration.