库水位升降速率对雅安双家坪堆积体滑坡稳定性影响模拟分析

摘要

水库蓄水后库岸边坡的稳定性一直是研究的热点,库水位周期性涨落使得坡体内部渗流场发生变化进而影响其应力场,应力场作用于岩土体产生变形,其中水库水位升降速率对滑坡稳定性的影响尤为显著.本文以瀑布沟水电站库区双家坪滑坡为研究对象,在调查分析的基础上,基于非饱和土力学理论,考虑水—土特征曲线与渗透特性,对库水作用下的双家坪堆积体滑坡稳态—瞬态进行渗流场—稳定性数值计算.运用GeoStudio软件中的seep模块模拟库水作用下滑坡体地下水变化,计算出不同库水位升降速率条件下堆积体滑坡内部渗流场的变化并将结果耦合至slope模块中进行稳定性计算,研究结果表明:水位抬升阶段,滑坡的稳定性表现为先升高再降低,且水位抬升速率越大,滑坡稳定性升高后衰减的程度越大;水位下降阶段,滑坡的稳定性表现为先降低再逐渐回升的趋势,且水位下降速率越大,滑坡稳定性下降后再回升的程度越低.该研究结果对于库区地质灾害防灾减灾、 监测预警以及水库合理调蓄具有重要的意义.%The stability of reservoir bank slope after impounding has been a hotspot for research, the periodic fluctuation of the reservoir water level can change the seepage field of the slope and then affect its stress field which can induces the deformation of the rock-soil mass. The effect of the reservoir water level fluctuation is especially significant for the stability of the landslide. In this paper, Shuangjiaping landslide at the Pubugou Hydropower Station Reservoir Area is chosen as the research object. On the basis of investigation and analysis, according to the theory of unsaturated soil mechanics, taking the soil-water characteristic curve and permeability into consideration, the stability and seepage value of Shuangjiapingaccumulation landslide under steady-transient conditions were calculated under the action of reservoir. Using the Seep module of GeoStudio software to simulate the landslide groundwater fluctuation under the action of reservoir, the changes of the internal seepage field in accumulation landslide under different reservoir fluctuation conditions were calculated and the results are coupled to the stability calculationin the slopemodule. The study results show that, as the water level rising, the landslide stability rise at first then get lower, and the higher the rate of elevation, the greater the extent of the decrease of the landslide stability. In water level decline phase, the stability of the landslide shows the trend first reduce gradually recover, and the higher the water level decline rate, the lower the extent of the decrease of the landslide stability. The study results have an important significance for the geological disaster monitoring and early warning, disaster prevention and mitigation, regulation of the storage capacity of reservoirs.