摘要
降雨条件下的边坡稳定性分析,需要同时考虑水的渗流与边坡内力进行耦合计算。非饱和土的特殊性质增加了计算难度,其渗透性、强度都会随含水量的变化而变化。介绍了非饱和土的有效应力原理,并比较了PLAXIS和Geo-Studio两款软件使用的有效应力原理和破坏准则的异同。PLAXIS软件中用有限元法计算非饱和土的渗流问题,利用简化的Bishop有效应力公式进行固结、变形及边坡稳定性计算,土体本构关系根据需要选用;Geo-Studio软件中也使用有限元法计算非饱和渗流,但其边坡安全系数计算方法为极限平衡法,强度准则为Fredlund双变量理论。最后结合算例详细介绍了PLAXIS软件中进行非饱和土边坡计算的建模方法。算例显示,PLAXIS软件中建立的计算模型可以准确反映降雨过程中边坡安全系数的变化规律。今后的工程设计中,可以考虑使用这一软件进行非饱和土边坡设计计算。
In order to analyze the slope stability in consideration of the rainfall influences, it is necessary to couple the calculation of the rainfall infiltration and the slope internal force. Special characteristics of the unsaturated soils make the calculation more complex, because the soil＇s hydraulic permeability and strength would change with moisture content. In the paper the principle of the effective stress of the unsaturated soils is introduced. The similarities and differences of the principle of effective stress and failure criteria used in the PLAXIS and Geo-Studio softwares are compared. In PLAXIS, the finite element method is used for unsaturated seepage calculation and a simplified Bishop effective stress formula is applied to the calculation of consolidation, deformation and slope stability. The constitutive models for the saturated soils can be used on that basis. The Geo-Studio uses the finite element method for the unsaturated seepage calculation and the limit equilibrium method for the calculation of the slope safety factor, in consideration of Fredlund＇s bilinear strength criterion. Finally, details of the method for modeling the unsaturated slopes in PLAXIS are presented with calculation examples. The calculation examples show that the models in PLAXIS can accurately reflect rainfall-induced slope safety factor variation. Therefore, this software can be adopted for the unsaturated soil slope design and calculation in the future.
出处
《水利水运工程学报》
CSCD
北大核心
2014年第3期70-76,共7页
Hydro-Science and Engineering
