The Dynamic Mechanical Properties Of Rough Joints And Its Effect On The Propagation Of Stress Waves

Rock mass is a general term for rock materials and structural surfaces.Joints are the most widely distributed structural surface.Due to the existence of structural surfaces,the rock masses exhibit complex properties of heterogeneity,discontinuity,anisotropy and non-linear elasticity.Jointed rock masses are often subject to cyclic dynamic loads.Under the effect of cyclic dynamic loads,joints mostly occur surface damage.At the same time,the existence of joints also affects the propagation of stress waves.The dynamic properties of joints and the influence on the law of stress wave propagation are related to the geometric characteristics of joint.In this paper,JRC and the joint distribution were used to study the dynamic properties of joints and its influence on the propagation of stress waves.In addition,the change of joint morphology was observed to study the damage law of joints under cyclic dynamic loading.Firstly,SHPB was used to conduct a cyclic impact test on joint samples with different JRC.The influence of joints on the law of stress wave propagation was discussed based on the stress wave transmission coefficient and stress wave energy loss.And the dynamic properties of joints were investigated according to equivalent elastic modulus and joint normal stiffness.The results show that JRC and the time of cyclic impacts significantly affect the dynamic properties of the joints and the law of stress wave propagation.Then,the SHPB device was used to conduct cyclic impact tests on samples with different joint distributions.The effects of joint distribution on stress wave propagation and the dynamic mechanical properties of joints were studied based on the joint distribution uniformity and joint thickness.It is found that joint distribution can significantly affect the dynamic properties of the joints and the law of stress wave propagation.Finally,3D topography scanning was used to compare the joint samples before and after impact.The results show that smooth,uniform and small joints changed less after cyclic impact.