有效应力原理在各向异性饱和土中的拓展与应用  

Expansion and application of the principle of effective stress in anisotropic saturated soils

作　　者：董彤 柘美 孔亮[2] 李长君 杨辉 房雨雨 DONG Tong;ZHE Mei;KONG Liang;LI Changjun;YANG Hui;FANG Yuyu(Institute of Defense Engineering,Academy of Military Sciences,People's Liberation Army,Beijing 100850,China;School of Sciences,Qingdao University of Technology,Qingdao,Shandong 266033,China)

机构地区：[1]军事科学院国防工程研究院,北京100850 [2]青岛理工大学理学院,山东青岛266033

出　　处：《岩石力学与工程学报》2020年第5期1040-1048,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51909268,51778311,11572165)。

摘　　要：有效应力原理奠定了土力学的基础。为了刻画由于土颗粒形状和排布的不规则所造成的内应力不均匀现象和土的各向异性力学行为,采用2种典型的分析方法对各向异性饱和土的内应力进行剖析,结果表明:对于各向异性土而言,忽略土颗粒接触面积后所得到的有效应力无法刻画内应力的不均匀现象;骨架应力是一个客观存在的物理量,可以刻画内应力不均匀的现象。为了便于应用,在骨架应力的基础上,提出等效应力张量,使之可以刻画不包含孔隙水压强的其他所有外力作用产生的土骨架应力。借助组构张量,给出等效应力张量的具体表达,明确有效应力、骨架应力和等效应力之间的两两换算关系。在此基础上,以等效应力刻画土骨架应力,以已有本构模型模拟土骨架力学行为,可以在不额外地修正土的基本力学规律的前提下,对各向同性土的本构模型进行"各向异性化"改造,实现有效应力原理在各向异性土中的拓展。以Lade破坏准则为例,建立等效Lade破坏准则,与试验结果对比表明,拓展后的有效应力原理可以适用于各向异性饱和土。The principal of effective stress is the foundation of soil mechanics. In this paper,two typical methods are used to analyze the inner stress of anisotropic soils in order to characterize the inhomogeneity of the internal stress and anisotropic mechanical behaviors of soil caused by the irregular shape and distribution of soil particles. The results show that,for anisotropic soils,the effective stress without considering the contact area of soil particles cannot describe the nonuniformity of the internal stress while the skeleton stress as a real stress can do. For ease of application,and referring to the physical connotation of the effective stress,an equivalent stress tensor is proposed to characterize the skeleton stress produced by all other external forces except for pore water pressure. The specific expression of the equivalent stress tensor is given with the fabric tensor,and the two-to-two conversion relations among effective stress,skeleton stress and equivalent stress are established. Moreover,using the equivalent stress to describe the soil skeleton stress and adopting existing constitutive model to simulate mechanical behaviors of soil skeleton,constitutive models of isotropic soils can be "anisotropized" without additional modification of the basic mechanical law of soils to realize the expansion of the principal of effective stress to anisotropic soils. Finally,as an example,the Lade’s failure criterion is transformed into the equivalent Lade’s failure criterion. Comparison with the existing experimental results proves that the expanded principle of effective stress is applicable to anisotropic geomaterials.

关 键 词：土力学 有效应力原理 骨架应力 等效应力 各向异性 强度 

分 类 号：TU431[建筑科学—岩土工程]