Study On The Influence Of Intermittent Joint Rock Mass On The Propagation Law Of Stress Wave

The natural rock mass contains a large number of discontinuous structural planes such as folds,joints,fissures and faults.The existence of these discontinuous structural planes destroys the integrity of the rock mass and greatly affects the strength,deformation and stability of the rock mass.The existence of joints in the rock mass often leads to the opening,closing and slipping of the structural surface in the rock mass,which greatly damages the stability of the rock mass structure.The stress wave will reflect and transmit as it passes through the joint surface,which in turn causes the amplitude of the stress wave to decay and the wave velocity to slow down.It is necessary to study the influence of jointed rock mass on stress wave propagation law.Rock mass joints are divided into continuous joints and intermittent joints.At present,most of the research objects of scholars on the influence of jointed rock masses on stress wave propagation are continuous joints.In terms of strength characteristics,there is very little research on the effect of intermittent joint rock mass on wave propagation.In view of this,this article will study the effect of intermittent joint on stress wave propagation law.Because of its good stability,safety and environmental protection,the ultrasonic experiment uses the RSM-SY6 ultrasonic detector to conduct the ultrasonic test.This study mainly considers the effect of joint penetration rate and number of joints on wave propagation.The research content is as follows:First,an RSM-SY6 ultrasonic tester was used to conduct ultrasonic experiments on a sample with intermittent joints of different penetration rates(0.4,0.5,and 0.75,respectively)and an unjointed joint.By analyzing the transmission waveform and spectrum amplitude diagram,the influence law of joint penetration rate on wave velocity,wave amplitude,main frequency and wave transmission coefficient is studied.The experimental results show that when the stress wave passes through an intermittent joint,both the amplitude and the velocity of the wave attenuate,and both the amplitude and the velocity decrease with the increase of the joint penetration rate.The transmission coefficient is negatively correlated with the joint penetration rate,and the tendency of the transmission coefficient to decrease as the penetration rate increases decreases.Secondly,ultrasonic experiments are conducted on the same penetration rate(0.5)and different numbers(1,2 and 3)of intermittent joint samples and non-joint samples.By analyzing the transmission waveform and spectrum amplitude diagram,the number of joints is discussed The law of influence on wave propagation.The experimental results show that the number of intermittent joints(not less than 1)has little or no effect on the wave speed.As the number of joints increases,the trend of decreasing amplitude decreases.Finally,the ultrasonic experiment was carried out on the 14 th and 28 th days of the sample curing.By comparing the experimental results of the same sample in two different curing times,the effect of curing time on the wave propagation results was discussed.The results showed that the initial wave amplitude and wave velocity of the samples with different numbers,intermittent joints and unjointed joints in the 28-day curing experiment were greater than the corresponding results in the 14-day curing.