库水位间歇性下降对堆积体滑坡稳定性的影响

摘要

Rapid drawdown of reservoir water level is adverse to landslide stability .In view of this , we propose that the reservoir water level declines intermittently .On the basis of traditional analysis of persistent drawdown of water level, we analyzed the influences of intermission and intermittent drawdown of water level on the stability of land -slide by using Geo-Studio software .An accumulation landslide in Three Gorges reservoir area was taken as an exam-ple.Research results show that intermission is in favor of the dissipation of pore water pressure in the landslide ;meanwhile , lag effect of groundwater level ’ s decrease caused by rapid drawdown of reservoir weakens and hydraulic gradient decreases;when we compare reservoir intermittent drawdown with reservoir persistent drawdown , landslide stability factor of the former is bigger , but stability factor is not in proportion with intermission;under the multistage intermittent drawdown of reservoir , stability factor has obviously improved ,which is greater than 5%.Finally, in or-der to optimize the landslide ’ s stability, we should reasonably arrange reservoir drawdown and intermittent time .%针对库水位快速下降不利于滑坡稳定的现状，提出库水位以间歇性方式下降，即在传统库水位持续性下降分析的基础上，以三峡库区某一堆积体滑坡为例，利用Geo-Studio软件详细分析了在库水位不同间歇时间和多阶段间歇下降条件下堆积体滑坡稳定情况。结果表明：库水位实行间歇性下降，间歇时间有助于滑坡体内孔隙水压力消散，减小库水快速下降引起的地下水回落的滞后性，有利于水力梯度降低；相比库水位持续性下降，滑坡稳定性得到提高，但稳定系数与间歇时间并不呈正比例关系；在库水位实行多阶段间歇性下降后，提高的程度明显增大，达到5％以上。为了使滑坡稳定性提高的效果达到最佳，应合理地安排库水位下降和间歇时间。