Parameters Influencing the Shear Behaviour of Clay Infilled Rock Joints

The rock masses are heterogeneous and contain discontinuities. The discontinuities existing in rock masses are normally filled with fine material such as clay. The presence of clay infill in discontinuities has a major influence on the stability of rock mass.

The shear behaviour of infilled joints is significantly controlled by several parameters such as the type of joint and infill material, surface roughness and thickness of infill, drainage condition, the degree of overconsolidation etc. It is expected that the difference in shear strength between normally and overconsolidated states may be very large and the degree of overconsolidation of clay infill probably exceeds even the most overconsolidated deposits. Furthermore, a real danger is in the underestimation of pore pressure change, softening, and swelling. Therefore, the effects of pore pressure and the degree of overconsolidation on clay filled rock joints are analysed carefully with proper laboratory simulation.