非饱和渗流下土石坝坝坡可靠性分析  

Reliability analysis of earth rock-till dam stability under saturated-unsaturated seepage

作　　者：韩波[1] 廖红建[1] 肖正华[1,2] 杨丽[1] 

机构地区：[1]西安交通大学,西安710049 [2]新疆大学,乌鲁木齐830008

出　　处：《应用力学学报》2010年第2期406-411,共6页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(50979087);西安交通大学自然科学基金

摘　　要：将饱和-非饱和渗流场统一起来,建立了饱和-非饱和渗流的微分方程。根据极限平衡原理,考虑基质吸力对抗剪强度的影响,采用延伸的摩尔-库仑破坏准则,建立边坡在非饱和土条件下的安全系数公式。运用饱和-非饱和渗流有限元程序,对土石坝工程进行了计算和分析,探讨了稳态和瞬态下库水位变化时,坝体内浸润面的变化、瞬态孔隙水压力分布情况。进一步采用蒙特卡罗法把渗流计算所得的瞬态孔隙水压力分布用于坝坡可靠性分析,计算坝坡的瞬态可靠指标,对土石坝在非饱和、非稳定渗流作用下,不同水位下降速度对上游坝坡可靠性的影响进行了研究。结果表明:库水位下降对坝坡产生饱和-非饱和渗流作用,渗流场受降速的影响大,库水位下降速度增大,坝坡稳定性降低;坝坡可靠指标与库水位的关系呈抛物线变化趋势,渗流浸润线开始比较陡,最后趋于平缓,而坝坡可靠指标表现为开始减小,经过一段时间达到最小值,然后逐渐增大。The saturated-unsaturated seepage differential equations of porous media are established by unifying saturated and unsaturated seepage field.Based on limit equilibrium theory and adopting the extend Mohr-Coulomb failure criterion to consider the effects of suction on shear strength of unsaturated soils,the safety factor equation for unsaturated soil slope is built.Applying the saturated-unsaturated seepage FEM program,one earth rock-fill dam project is calculated and analyzed.When the reservoir water level changes,the position of the phreatic surface and the transient distribution of the pore water pressure is discussed.Furthermore,the calculated transient pore water pressure distribution is applied to the reliability analysis of dam slope by using the Monte Carlo simulation.The transient reliability index of dam slope is calculated.The effects of descending speed of water level on the reliability of upsteam dam slopes are studied under unsaturated and unsteady seepage.It is shown that the saturated-unsaturated seepage is caused by the drawdown of reservoir water level for dam slope.The seepage field is affected by the drawdown rate of reservoir water level.The quicker the descending speed is,the less the stability of dam slope is.The relationship between the reliability index of dam slope and the reservoir water level shows a variation of parabolic type.Initially,the phreatic surface is steep,and it tends to be flat finally.Correspondingly,the reliability index of dam slope is decreased at first.Through a period,it reaches its minimum.Then,the reliability index of dam slope increases gradually.

关 键 词：饱和.非饱和渗流 可靠指标 边坡稳定性 土石坝 

分 类 号：TU452[建筑科学—岩土工程]