旭龙水电站库区格亚顶堆积体变形及稳定性分析

Deformation and stability analysis of Geyading accumulation body in Xulong Hydropower Station reservoir area

为了分析库水位变化对坡体变形及稳定性的影响,以金沙江上游旭龙水电站库区中的格亚顶堆积体为例,利用GeoStudio软件对库水作用下的坡体进行渗流、应力-应变、稳定性数值模拟计算,预测在库水作用下坡体的变形及稳定性变化规律。结果表明:①在库水位上升过程中,地下水位线有向坡内弯折下凹的趋势并明显滞后于库水位,应力和位移随库水位上升变化明显,稳定性系数持续增加;②在库水位维持不变过程中,地下水位线随库水位维持时间逐渐趋于平缓并有局部重合现象,应力和位移在一定范围内波动变化较小,稳定性系数在不同水位维持一定时间后都出现明显变化;③库水位下降过程中,浸润线下降幅度随时间逐渐减小,应力和位移相对于水位上升阶段变化较小,稳定性系数则持续减小。根据稳定性系数变化规律,结合数值计算获取的位移曲线,通过累加法处理得到累积位移曲线并计算单位时间的切线角,利用切线角预警判据对该水库蓄水运行后的变形阶段进行判别,格亚顶堆积体在水库运行初期的变形阶段为初加速变形阶段。

In order to analyze the influence of reservoir water level change on the deformation and stability of slope bodies,taking the Geyading accumulation body in the reservoir area of Xulong Hydropower Station in the upper reaches of Jinsha River as an example,the GeoStudio software was used to carry out numerical simulation on the seepage,stress-strain and stability coupling under the effect of reservoir water to predict the change rule of the deformation and stability.The results show that:①During the rise of the reservoir water level,the groundwater level is likely to bend and concave to the slope internal direction and obviously lag behind the reservoir water level,the stress and displacement change obviously with the rise of the reservoir water level,and the stability coefficient continues to increase.②In the process of reservoir water level maintenance,the groundwater level line with the reservoir water level maintenance time gradually tends to flatten and there is a local overlap phenomenon,the stress and displacement in a certain range of fluctuation change is small,the stability coefficient in the different water level maintenance for a certain period of time after a certain period of time all appear obvious changes.③During the decline in reservoir level,the seepage line decreases with time,the change of stress and displacement are less than that in the water rising stage,and the stability coefficient continues to decrease.④According to the variation law of stability coefficient,combined with the displacement curve obtained by numerical calculation,the cumulative displacement curve is obtained by the accumulation method and the tangential angle per unit time is calculated.The early-warning criterion of tangential angle is used to distinguish the deformation stage of the reservoir after impoundment.In the initial stage of reservoir operation,the accumulation body is in the initial accelerated deformation stage.