Title : Effect of infill thickness in the joint under cyclic loads
Abstract:
Many of the joints may have been filled by transported material or joint walls being weathered. In comparison to the joint blocks the filling material is much weaker as it is generated by rock fracturing or weathering of joint block material. Infilled joints exist in many cases of rock masses and failure is related to low resistance of infill materials. In order to assess the effect of infill thickness on shearing plane, two types of planar and non-planar synthetic infilled joints are prepared. These joints are prepared with plaster of Paris and tested under CNS boundary condition. Sample size of joints is kept at 298*298*125 mm. In between the joints; infill material of thickness 5mm and 10mm is placed to create infilled rock joints. These joints were tested under different boundary condition at different initial normal stresses (Pi) by keeping frequency and amplitude constant under cyclic shear load, using servo controlled large scale direct shear apparatus. Test results indicate that there is no change in normal stress under CNS on the shearing plane and it remains constant at Pi for planar infilled joint. But for non-planar joints it changes with changing in the infill thickness and number of shear cycle. lnfilled material thickness and initial normal stress play important role on cyclic shear behavior of non-planar infilled joints under CNS boundary condition. Moreover, experimental tests indicated that there is no effect of CNS boundary condition on shear behaviour of infilled joints at both high normal stress and infill thickness.
