How to rapidly and accurately determine joint normal stiffness in rock mass is an important issue in rock engineering. In this work, a new method, i.e., the rapid evaluation method, was introduced to determine the normal stiffness of joints. This method was derived from one-dimensional compressional wave propagation theory. The effect of joints on wave propagation is modelled by displacement discontinuity model as a boundary condition in solving wave equations. Together with input parameters from laboratory or field ultrasonic tests, joint normal stiffness was inversely determined. Direct measurements of joint normal stiffness were performed from uniaxial compression tests. The joint normal stiffness predicted by the rapid evaluation method was then compared with that from direct laboratory measurements. The results show that joint stiffness determined from the rapid evaluation method agreed with their corresponding experimental values, which confirms that this proposed method is valid and feasible.

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