水位骤降对边坡稳定性影响的模型试验及数值模拟研究

Model test and numerical simulation study of slope instability induced by rapid drawdown of water level

自然或人工边坡的稳定性研究是当前岩土工程研究领域的热点问题之一。随着三峡等大型水利设施的兴建和投入使用,水位骤降对边坡稳定性影响也引起人们的广泛关注。通过室内模型试验研究水位骤降引发临水边坡滑坡的原因及失稳模式是经济、便捷的常用方法。本试验模型箱的尺寸为2.5m×1.5m×1.5m(长×宽×高),边坡高度为1.05m。边坡体内埋设了10只土压力盒和7只渗压计,用于测量水位骤降过程中土压力和孔隙水压力的变化情况,记录边坡失稳破坏过程中土体内部的变化过程。同时,利用geo-slope软件模拟边坡失稳破坏的整个过程,并且利用数值模拟的结果与试验结果进行对比分析,解释边坡破坏的机理。试验结果表明:水位骤降对边坡稳定性产生很大影响,水位下降速度越快,边坡沉降也就越大,最后形成明显的位移集中区域;边坡的安全系数分别随着水位高程的减小、水位下降时间的增加出现增加最后趋于稳定;在此土质、坡形条件下的边坡破坏的形态与数值模拟所得8min时滑动面的形态相吻合,据此也用试验验证了数值模拟的可靠性。

Natural or artificial slope study is the current hot topic of research in geotechnical engineering.Rapid drawdown of water levels causes people to attention with Three Gorges and other large water conservancy being put into use.A model test performed to investigate the failure model and causes of landsides of the slope during rapid drawdown of water level is economic and convenient method.The model slope is 2.5m long,1.5m high,1.5m wide,and the height of slope part is 1.05m.There are ten earth pressure cells and seven osmometers in the slope.They are used for measuring earth pressure and pore water pressure during rapid drawdown of water levels.The results are record of the process of slope instability.At the same time,the geo-slope is used for simulating the process of slope instability.The mechanism of slope instability is explained through comparing the result of numerical simulations with experimental result.The experimental results provide that rapid drawdown of water levels has a significant impact on slope stability.The faster the speed of water levels falls,the bigger the slope settlement is.Finally the clear displacement focus area in the slope is formed.Safety factor with the decrease of the water level and the increase of the water level fall time increases at first and keeps steady state at last.The shape of slope destruction under the condition of soil and shape matches the shape of 8min slide under numerical simulation.It indicates the reliability of the numerical simulation according to the experiment.