库水位变动情况下库岸边坡稳定性研究——以白鹤滩水电站石圪垴滑坡为例

Study on stability of reservoir bank slope under fluctuated water level： A case of Shigenao Landslide in Baihetan Hydropower Reservoir

摘要:

精细化研究库水位变动对库岸边坡稳定性影响具有重要意义，本文以白鹤滩水电站库区石圪垴边坡为研究对象，通过地质分析，结合普适性监测仪GNSS位移监测数据、气象站降雨数据及库水位涨落数据，并利用饱和-非饱和渗流有限元软件模拟不同库水位以及库水位以不同速度下降20 d后边坡稳定性。研究结果表明：稳定渗流情况下岸坡安全系数较瞬态渗流情况下增大约17.6%，库水位上升岸坡稳定性增加，反之，稳定性系数降低。库水位降速越大，岸坡稳定性降低越明显，降速相差0.5 m/d，稳定性系数下降约3.2%。库水位下降前期稳定性系数下降较为明显，第10天稳定系数降至最低，与现场GNSS监测数据结果具有高度一致性，监测数据的变化提前预报了滑坡的发生，显示了普适性监测仪器的监测成效与预警作用。

Abstract:

Refined study of the influence of the water level flucration on bank slope stability is of great significance. Taking the Shigenao Landslide in Baihetan Hyreopower Reservoir as an example in the paper， based on geological conditions， combined the monitoring data of universal geo-hazrad monitoring instrument， rainfall data from the meteorological station and reservoir water level fluctuation data， the stability of the slope in different water levers and water lever dropped over 20d in differente speeds was simulated by the finite element method. The results show that the safety factor increases about 17.6% in the stable seepage flow compared with the condition of transient seepage， the stability increased as the reservoir water level rises， otherwise the stability decreases. The greater the drop rate of reservoir water level， the worse the stability， and the stability decreases by about 3.2% when the develeration rate increases by 0.5m/d. The factors of stability decreases significantly in the early stage， and reached to the lowest in the 10^th day，which is highly coincide with the GNSS monitoring data. The monitoring data predicted the occurrence of the landslide in advance which shows the monitoring effect and forewarning funtion of the universal monitoring instrument.