基于降雨-库水联合作用下三门洞滑坡演化过程与机制

三峡水库自2003年6月蓄水以来,大量滑坡发生了复活变形。为研究在库水位升降和降雨联合作用下滑坡复活变形的演化过程与机制,以秭归县三门洞滑坡为例,基于滑坡长期的地表位移监测数据,分析了滑坡变形的时空演化过程;基于领域粗糙集理论,对滑坡复活变形的主要诱发因素进行了判别;通过数值模拟分析了滑坡的变形演化趋势。结果显示,三门洞滑坡受周期性水位下降和汛期降雨的影响,其累计位移具有明显周期性和阶跃性。在空间上,滑坡不同部位的变形诱发因素并不相同,滑坡中后部变形主要受降雨影响,前部变形则主要受库水位下降影响。整体上滑坡变形对降雨和库水位的响应均存在一定的滞后性,变形强度从前至后逐渐减弱,为典型的牵引式变形模式。滑坡在快速降低水位并叠加暴雨后处于最危险状态,虽然滑坡目前处于基本稳定状态,但安全储备不高,随着变形的持续增加,在汛期和暴雨情况下存在整体失稳的可能,研究结果为同类型滑坡的防治提供了一定参考。

Evolution Process and Mechanism of Sanmendong Landslide Based on Combined Effect of Rainfall and Reservoir Water

Since the impoundment of the Three Gorges Reservoir in June 2003, many landslides have been reactivated. In order to study the deformation evolution process and mechanism under the combined action of reservoir water level fluctuation, taking Sanmendong landslide in Zigui County as a typical case. Combined with the long term monitoring data of surface displacement of the landslide, the process of spatial temporal evolution is analyzed. Based on the theory of domain rough set, the main inducing factors of reactivation of landslide are distinguished. The deformation evolution trend of landslide is analyzed by numerical simulation. The results show that the Sanmendong landslide is affected by periodic water level drop and rainfall in flood season, and its accumulated displacement has obvious periodicity and step like in shape. The induced factors of deformation in different parts of landslide are different. The deformation in the mid rear part of landslide is mainly affected by rainfall, while the deformation in the front part is mainly affected by the drop of reservoir water level. On the whole, the response of landslide deformation to rainfall and reservoir water level has certain hysteresis, and the deformation strength gradually weakens from the front to the back, which is a typical traction deformation mode. It shows that the stability of landslide is the worst after rapidly dropping of reservoir and superimposing rainstorm. The safety factor of landslide is not very high although it is in the basic stable state at present. With the increase of deformation, there is possibility of overall instability under conditions of flood season and rainstorm. The results provide a certain reference for the prevention of similar landslides.