Theoretical And Numerical Study On Wave Propagation Characteristics In Non-persistent Jointed Rock Masses

The joints and other discontinuities existing in rock masses have significant effect on wave propagation,which shows great importance to practical engineering activities.Wave propagating through non-persistent joints that consist of joint segments and rock bridges is more essential to be studied because non-persistent joints accounts for great proportion within rock masses and is able to characterize the discontinuity property of rock masses better than fully-persistent joints.This thesis presents a theoretical study and the numerical modeling to investigate the effect of non-persistent joints on the transmission coefficients of normally incident wave propagation across rock masses.In the theoretical study,the transmission coefficients in the transmitted field for wave passing through a single non-persistent joint is calculated by taking into account the attenuation impact of joint segments with the displacement discontinuity model,and by considering the wave diffraction around each rock bridges with the angular spectrum theory at the same time.Then,the wave transmission coefficients for normally incident wave passing through a single non-persistent joint with different length of joint segments and rock bridges are studied by using finite element method(FEM)and discrete element method(DEM),and an agreement between theoretical solutions and numerical modelling results is achieved to verify the feasibility of theoretical method.It is found that the length of rock bridges has positive influence on the distribution of transmission coefficients in transmitted field,while the length of joint segments has negative effects.In the numerical simulation,parameter studies are conducted to study the effect of multiple non-persistent joints on the wave transmission coefficients for normally incident wave based on FEM.The results of particle vibration after non-persistent joints are measured as the superposition of diffracted wave and transmitted wave.The joint spacing and number of joints show major effects on multiple wave reflection and transmission among multiple joint segments.The joint dislocation induces more wave attenuation by dislocated joint segments.Wave energy transfers from crest to valley of wave with the wave propagation distance increasing.