The research was performed to assess the effects of cyclic loading on deformation behavior of saturated Phu Kradung sandstone of the Khorat Group under confining pressure and rock anisotropy. The cylindrical specimens were prepared for two orthogonal directions, normal and parallel (0 and 90 degree) to laminations to enable the anisotropic observation. Monotonic and cyclic loading tests were conducted under unconfined and confining pressures of 6, 12, 20 and 30 MPa. The results from both types of loading tests indicate that the level of confining pressure had a significant influence on the cyclic deformation of the saturated samples tested. The residual axial strains of samples obtained at a confining stress state can be described as three deformational stages, namely, the initial phase, uniform phase and final phase. The direction of loading in relation to its lamination demonstrates large difference in number of cycle reaching failure at unconfined stress condition, but insignificant effect under confined stress condition.
