Laboratory and Numerical Modelling of a Jointed Rock Mass

Laboratory tests were performed on 54 large size specimens of jointed rock mass under uniaxial loading conditions. Based on this experimental study, a methodology has been suggested to estimate strength and tangent modulus of rock masses through a weakness coefficient. The methodology involves mapping of joints in the field and laboratory testing of intact rock specimens to arrive at rock mass properties. The laboratory tests have also been analysed numerically through distinct element modelling. An interesting outcome of the physical and numerical modelling is the observation of a new geological phenomenon, that the lateral strain ratio of jointed rock mass may be extremely high and exceed 0.5, if the joints are oriented critically. This phenomenon is very significant in safe design of rock bolts in underground caverns. It is shown that distinct element method may be used with confidence to simulate the failure mechanism of rock masses and occurrence of high lateral strains in unconfined conditions.