Problems of the structural rheology of clays: Fid-Bau Portal

Problems of the structural rheology of clays

Vyalov, S. S. / Zaretsky, Yu. K. / Maximyak, R. V. / Pekarskaya, N. K.

Summary Relationships in soil mechanics are usually described by phenomenological equations obtained from the study of macroprocesses. If the relationship between micro- and macroprocesses are established, it becomes possible to give an analytical description of the deformation and the long-term failure of soils on the basis of the physical nature of these phenomena. This paper sets forth the results of such investigations. Changes in the microstructuure of clays in the process of deformation were investigated by optical and electron microscopes and the dependences of these changes on the magnitude of the load, the duration of the process and the stage of deformation were established. It was found that the long-term deformation process of clays (creep phenomenon) is accompanied by a displacement and reorientation of particles, and a formation of microfissures, which leads to long-term failure of the soil and to a decrease of its strength in time. The relationship of the indicated microprocesses was established and the failure criterion of clayey soils was determined. In studying the changes of the structure of clays from the point of view of the activation processes, the authors established a connection between the kinetics of the structural changes and the deformation rate of soils on one hand, and their failure time on the other. As a result, equations of deformation and long-term strength of clayey soils were obtained. They are based on the investigation of the physical essence of these processes. A comparison of the above-mentioned equations with test data yielded a good coincidence.