摘要
瑞典条分法在土力学教学和边坡工程设计中有着广泛的影响。针对其两种有效应力分析表达式,通过剖析土条底面法向有效应力的推求过程及对比分析计算结果发现:在理论上,两种表达式都不适用于一般渗流条件下的边坡稳定分析;实用上,也存在明显离散的计算误差。其原因分别在于:以土体为研究对象时,忽略了土条侧面的水压力;以土骨架为研究对象时,忽略了渗流力的作用。进一步分析微单元体平衡微分方程的结果表明,Taylor提出的分析渗流对土骨架有效应力影响的两种等效处理方式,即以土体为研究对象,考虑饱和重力与周界上水压力的方式;或以土骨架为研究对象,考虑有效重力与渗流力的方式,可以在刚体极限平衡分析方法中运用,例如条分法。但是,在涉及渗流-变形耦合分析的诸如边坡渗流稳定和固结问题的解析和数值方法中,只能以土体为研究对象,而不能以土骨架为研究对象、运用渗流力的概念进行分析。究其原因在于:在渗流条件下,物理上,有效应力不是应力变量;有效应力和确定渗流力的孔隙水压力分别是决定土骨架的变形和强度以及流场的相互依赖的、非独立的应力状态变量。
The Swedish slice method has played an important role in the teaching of soil mechanics and the design of slope engineering. Its two expressions for effective stress analysis are investigated by anatomizing the derivation process of the normal effective stress on the bottom of a soil slice and by analyzing their calculated results comparatively. It is found that theoretically both expressions are not applicable to the slope stability analysis under the seepage condition in a general sense, and practically their calculation errors are obvious and scattered. The reason for this is due, respectively, to the neglect of the boundary water forces on the sides of soil slices when soil mass element is analyzed and the neglect of the seepage forces when soil skeleton element is analyzed. Furthe：7 investigations on the differential equations of force equilibrium of a soil element reveal that the two equivalent approaches proposed by Taylor for treating the influence of seepage on the effective stress of soil skeleton, namely, the approach considering saturated weight and boundary water force when soil mass is analyzed and the approach considering effective weight and seepage force when soil skeleton is analyzed, can be used in the limit equilibrium analysis methods for a rigid body such as the slice method. However, in the analytical and numerical methods for seepage-deformation coupling analysis fox＇ problems like slope seepage stability and consolidation, only the soil mass element can be considered. Under this circumstance, the soil skeleton element cannot be considered and the seepage force concept cannot be applied. The reason for this is that under the seepage condition the effective stress is, physically, not a stress variable. The effective stress and pore water presst^re determining the seepage force are interdependent and non-independent stress state variables controlling correspondingly the deformation and strength of soil skeleton and the flow net field.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2012年第4期667-676,共10页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(50878075)
江苏省高校青蓝工程基金资助项目
中央高校基本科研业务费专项资金资助项目
关键词
条分法
有效应力
渗流力
应力变量
应力状态变量
耦合
slice method
effective stress
seepage force
stress variable
stress state variable
coupling
