关于土的特性及认识理论的思考

讨论了土力学中的以下基本问题:弹性和塑性概念,探讨了不同弹性定义对理论验证的影响;均匀性和结构性,说明孔隙演化及结构层次等非均匀性因素使得土的性质复杂;宏观场和微观场的关系,建议用一种考虑细观能量耗散的方法,用微观场的综合指标反映宏观力学性质;剪胀性和偏斜塑性,从理论和实验两方面分析了两者之间的关系;Drucker和Ilyshin两假设与不可逆热力学的关系,阐述塑性力学可以不依赖于这两个假设;宏细观相结合理论,提出一种退化细观力学方法,其材料函数和常数可由宏观试验反演确定。

Consideration on Characteristics and Recognition Theories of Soils

Author gives out his views of point on some fundamental concepts commonlyused in soil mechanics based on author' s understanding. Discussed properties of soils include: ELAS-T1CITY and PLASTICITY, discussion is focused on how different definitions of elasticity have the effect on theory verification. HOMOGENEITY and MICROSTRUCTURE. Pore motion and evolution and the sublayer of microstructures, which consists of heterogeneity, is the essence of intricate mechanical behaviors of soils. MACRO-FIELD and MICROFIELD. The first is how to express micro-field complextely ,fractal may be a useful tool. The second is how to connect the complex index with macroscopic mechanical behaviors. A method is suggested which considers energy dissipation mechanism in microscopic scale. DILATANCY and DEVIATORIC PLASTICITY. A definite relation is verified by many experimental data. Author derived out it from a micromechanical model. Discussed recognition theories include two:RELATIONSHIP BETWEEN DRUCKER POSTULATE, I-LYUSHIN POSTULATE and IRREVERSIBLE THERMODYNAMICS. The postulates are the direct sequence of entropy inequality, expressing complementary energy (Drucker) and free energy (I-Ivushin) reach maximum and minimum respectively,and are unnecessary for plasticity. So it is impossible to describe total behaviors of soils based on them. MACRO / MICRO COMBINATION THEORIES. A simplified micromechanics method, whose material functions and constants determined by macroscopic test data,makes micromechanics applicable in engineering. Other problems are also discussed in this paper.