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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 system of divisions has a wide range of implications in soil mechanics teaching and slope engineering design. According to the two expressions of effective stress analysis, by analyzing the deducing process of normal effective stress in the bottom surface of soil slice and comparing the calculated results, it is found that in theory, neither of the two expressions are suitable for slope stability analysis under general seepage conditions In practice, there are also obvious discrete discrepancies in calculation. The reasons are as follows: When considering the soil as the research object, the water pressure on the side of the soil is neglected. When the soil skeleton is the research object, the effect of seepage force is ignored. The further analysis of the differential equations of the micro-unit body balance shows that Taylor’s two equivalent treatment methods to analyze the effect of seepage on the effective stress of the soil frame are as follows: taking the soil as the research object, considering the way of the saturated gravity and the surrounding water pressure ; Or soil skeleton as the research object, consider the effective way of gravity and seepage force, can be used in rigid body limit equilibrium analysis methods, such as the stripe method. However, in the analytical and numerical methods involving seepage-deformation coupling analysis such as slope seepage stability and consolidation, only the soil can be the object of study, not the soil skeleton as the research object, and the concept of seepage force analysis. The reason is that under the condition of seepage, the effective stress is not a stress variable; the effective stress and pore water pressure to determine the seepage force are the interdependent and dependent stress that determine the deformation and strength of the soil skeleton and the flow field, respectively State variables.