Shear behavior of clay in slope for pore water pressure increase

Abstract

Shear behavior of clay in slope for pore water pressure increase was investigated with both triaxial compression and ring shear apparatuses. Not only shear strength but also shear deformation was examined. Pore water pressure loading test was conducted with tiaxial compression apparatus. Yield and failure points for pore water pressure increase were obtained. It was shown that yield point was on the critical state line described by internal friction angle of φ'. It means the design method with φ' indicates the design to prevent slope from instability and deformation occurrence. Shear displacement in pore water pressure loading test revealed time dependent behavior as creep. It was made clear to be caused by water migration and successive progressive failure. Creep behavior of landslide was discussed from the viewpoint of coupling theory in continuum. Stress controlled ring shear test was implemented for both virgin and re-sliding type landslide conditions. In virgin type landslide test, shear displacement increased with the decrease in normal stress. Yield and failure points were obtained. It was clarified that yield points were on the internal friction angle line obtained by strain controlled ring shear test. On the contrary, shear displacement was found to be fragile and to increase sharply at yield point in case of re-sliding type landslide test. Yield points were found on the residual internal friction angle line. Discussion on consolidation effect on yield and failure points was carried out in detail. © 2007 Springer-Verlag Berlin Heidelberg.