Vibration Equipment Development Of Rock Block Compression Wave Velocity

The compression wave velocity of rock mass is an important parameter reflecting the physical properties of rock mass,the development of internal joints and fissures,and the integrity of rock mass.It is an urgent work in the field of rock mechanics to accurately measure the compression wave velocity of rock mass.The methods mentioned in the standard are seismic wave method,ultrasonic method and so on,but the method used for rock block wave velocity test is only ultrasonic method.Due to the different frequency of seismic wave and ultrasonic,the wave velocity values measured by the two methods are different.Therefore,the compression wave velocity obtained by vibration method can more objectively reflect the degree of rock integrity.Based on the above analysis,the compression wave velocity of rock block is measured accurately based on vibration method using selfmade equipment and proposed test method.The main research elements include:(1)A test equipment has been developed,which is a new type equipment for rock block velocity vibration testing.The equipment has the following characteristics: First,the fixing device is easy to operate and use,which can fix the rock sample,effectively prevent the rock sample from moving with the sensor,reduce the test error and improve the test accuracy;Second,the previous fixed rock device is improved,which is convenient to stick the sensor for testing while fixing the rock sample;Third,vibration acceleration sensor The device has good highfrequency characteristics,pass band of 0.5~10kHz,light weight,small volume,easy to paste with the sample,convenient for experiment;Fourth,multiple equipment can be connected according to the length of the rock sample.(2)Based on the previous ultrasonic wave velocity test,a method of longitudinal wave velocity test of rock block using vibration test equipment is proposed.The rock blocks with different lithology,size and weathering degree obtained by coretaking are tested and analyzed.The results show that the maximum relative error between vibrationmethod and ultrasonic method is 8.57%.Using vibration method to test the longitudinal wave velocity of rock block can effectively reduce the influence of frequency dispersion effect on wave velocity and improve the test accuracy.(3)Based on the correlation between the horizontal vibration acceleration at both ends of the rock block,a matlab crosscorrelation program is developed to calculate the compression wave velocity of the rock block,and compared with the results of ultrasonic method and numerical simulation.The results show that the compression wave velocity is affected by the density,hardness and the development of structural plane.The compression wave velocity increases with the increase of density,hardness and strength,and decreases with the increase of joints and fractures.