Study on strength characteristics and permeability of chlorite schist during triaxial compression permeability

Abstract

In order to grasp the strength characteristics and permeability of chlorite schist, the triaxial compression permeability test of chlorite schist was carried out by using a rock triaxial servo testing machine equipped with seepage device. Based on the test results, the failure strength, initial permeability and permeability development of rock samples under different confining pressure and different pore water pressure are compared, and the failure types of rock samples under triaxial compression permeability and their influence on permeability are analyzed. The results show that the increase of confining pressure is conducive to the improvement of failure strength of chlorite schist, and the increase of pore water pressure reduces the failure strength, which is related to the inhibition of crack development in rock samples by confining pressure and the promotion of crack expansion by pore water pressure. The mechanical deformation of chlorite schist in triaxial compression permeability process has experienced initial compaction stage, linear elastic stage and crack stable propagation to failure stage. As a consequence, permeability shows three trends of decline, stable development and rise, which is closely related to the development of the internal structure of rock samples at each stage. During the failure of triaxial compression permeability, there is a local compression zone in chlorite schist, and the rising rate slows down due to the influence of the compression zone.