Propagation Characteristic And Application Of Stress Wave Across The Macro Jointed Rock Mass

Joints test of elastic parameters are the hot and difficult problem of rock mechanics discipline.It's great influence of joints on stress wave propagation in rock mass,the different types of joints,the effect is also different.The influence of linear deformation joint and stratified rock mass and nonlinear joint on stress wave are studied based on theoretical analysis,numerical calculation and field test.And the method of testing the joint's elastic parameters is deduced.In this process,the main study results as follows:(1)The transmission coeffcient of amplitude decreases with increasing frequency,it's shown that linear deformation joint has low-frequency filter characteristics,and the low-frequency filter characteristics is more evident with less joint stiffness.Through numerical computation,it's shown that it cannot calculate the reflected wave accurately by using the displacement discontinuity model to discribe the deformation behavior of the joint,but the trasmissed wave is accurate.(2)Normally P-wave propagation across the stratified rock mass and the interface is linear deformation joint and several rocks are same,the filter mode of stratified rock mass is the multi-scale comb filtering properties.The transmitted coefficient is periodic variation with rock stratum's thickness,and the amount of rock stratum doesn't change the period.When the rock stratum's P-wave velocity is decreasing with arithmetic progression,the filter property is low pass.(3)Normally incident wave with single frequency propagation across the nonlinear joint,the transmitted wave is multi-frequency wave which concluding basic harmonic wave and multiple harmonic wave.Meanwhile,it is found that there is a negative exponential function between harmonic amplitude and harmonic order,the harmonic phase and harmonic order meet the linear relationship.The initial phase of incident wave don't bother the harmonic amplitude of transmitted wave.(4)The result of numerical computation indicated that the testing result of testing joint's elastic parameters method for jointed rock masses are less than 2.00%,it is proved that the testing method is reasonable.Chosen a typical joint which thickness is 0.04 mm in slope beside Luojiang mineral water plant,6 tests have done,and the test result are similar.The elastic modulus and Poisson ratio of joint are 6.03 GPa and 0.19.