三峡水库蓄水以来，不少滑坡监测位移-时间曲线呈阶跃变化，导致稳定状态识别难度较大，严重影响滑坡预警预报，靠椅状土质滑坡尤为明显。本文以八字门滑坡为例，通过多次野外地质调查、长期现场巡查、10多年的GPS位移监测数据、2年多全自动监测数据等，较深入研究了该滑坡在库水涨落及降雨条件下变形规律。结果表明。库水位下降期间，特别是库水位下降15m以后，由160m下降至145m，滑坡体变形存在20d左右的滞后，滑坡变形曲线出现突跃，日位移量达1.5mm/d-2.2mm/d。一次降雨量在80mm以上会明显诱发坡体加速。库水位上升期间，库水位在175m左右时，月位移量出现5-10mm负值。一次降雨量在150mm左右未能诱发坡体加速；但一次降雨量在200mm以上，滑坡体位移速度明显加大。滑坡体在降雨量诱发后，位移加速后在降雨结束后持续5-7d恢复正常水平。在周期性降雨和库水位涨落的循环作用下，滑坡体反复受到“推-拉”作用，导致滑坡的位移-时间曲线呈阶跃特征。靠椅状土质滑坡为一类特殊的滑坡，库水位升降是八字门滑坡目前变形的主要因素，而降雨对滑坡变形起到了促进作用。受靠椅状等坡体结构特征制约，在库水位升降作用下坡体会反复变形，但难以发生快速的整体破坏。

Since the impoundment of the Three Gorges Reservoir, the displacement-time curve of many landslides has changed stepwise, which makes it difficult to identify the steady state, which seriously affects the landslide warning and forecast. It is especially obvious by chair-shaped soil landslide. Taking the Bazimen landslide as an example, this paper has studied the landslide in the reservoir water through multiple field geological surveys, long-term on-site inspections, GPS displacement monitoring data for more than 10 years and more than 2 years of fully automatic monitoring data. Deformation law under fluctuations and rainfall conditions. The results show that during the decline of reservoir water level, especially after the reservoir water level drops by 15m, it will decrease from 160m to 145m, and the landslide body deformation will have a lag of about 20a. The landslide deformation curve will suddenly jump, and the daily displacement will reach 1.5mm/a -2.2mm/ a. A rainfall of more than 80mm will obviously induce the acceleration of the slope. During the rise of the reservoir water level, when the reservoir water level is around 175m, the monthly displacement will have a negative value of 5-10mm. A rainfall of about 100mm failed to induce the acceleration of the slope; but once the rainfall was above 200mm, the displacement speed of the landslide body increased significantly. After the rainfall is induced, the landslide body accelerates to a normal level after 5-7 years of rain. Under the cyclical action of periodic rainfall and reservoir water level fluctuation, the landslide body is repeatedly subjected to the “push-pull” effect, resulting in the step-time curve of the landslide's displacement-time curve. The chair-like soil landslide is a special type of landslide.The water level rise and fall of the reservoir is the main factor of the current deformation of the Bazimen landslide, and the rainfall has promoted the deformation of the landslide. Restricted by the structural characteristics of the chair and other slopes, the slope will be repeatedly deformed under the action of the water level rise and fall, but it is difficult to cause rapid overall damage.

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国家重点研发计划项目（2018YFC1504803），国家青年科学基金项目(41502291、41602301)，防灾减灾湖北省重点实验室（三峡大学）开放基金（2018KJZ03），三峡库区地质灾害教育部重点实验室基金（2017KDZ07），湖北省自然科学基金面上项目（2018CFB654）。