Study On Acoustic Emission Characteristics Of Rock-like Materials With Different Volumetric Heterogeneities

In order to understand the relationship between the rock-like material under different volumetric heterogeneity and the relative clam period of acoustic emission.This paper combines the study of the relationship between the size of mineral particles and the relative clam period of rock acoustic emission in National Natural Science Foundation of China(51664018).By constructing the different volume non-homogeneity specimens to analyzing.The composition of various types of specimens consists of two different sizes of quartz sand.The most homogeneous particle type is A which consists of 0.16~0.315 mm and 0.16~0.135 mm while the mass ratio is 1:1;0.16~0.315 mm and 1.25~1.5mm particle size quartz sand particles are mixed to form the E type specimen which the internal particle volume is the most inhomogeneous.Through the acoustic emission test and subsequent parameter analysis under the uniaxial compression condition of five different volume non-homogeneity specimens,the main conclusions are as follows:(1)The deformation characteristics of rock-like materials with different volumetric non-homogeneity in uniaxial compression are similar to those of rock,which can be roughly divided into four stages:(1)initial compaction stage(2)elastically deformed and micro-elastic cracks develop steadily stage(3)plastic stage(4)instability failure stage,the failure modes of various types of specimens are similar,and as the internal particle volume of the specimen becomes increasingly non-homogeneous,its destruction form gradually transforms from brittle to ductile,and the compressive strength shows a decreasing trend in the mass.(2)In the analysis of b-values of acoustic emission and associated dimensions,the b-values of acoustic emission and associated dimensions of most of the specimens under five different volume non-homogeneity conditions decrease when the stress is near the peak stress.(3)In the analysis of r values of acoustic emission,the failure of the specimens was dominated by failure of the inter-particle sliding,all of the specimen reach the a plateau after peak stress.And the more inhomogeneous of the internal particle volume of the specimen is,the greater of the percentage of stress(4)In the analysis of peak frequency,according to the peak frequency range of acoustic emission collected by the sensor,the collected peak frequency distribution range is divided into 8 intervals,and the most frequently-occupied frequency interval is counted as the main frequency,the second highest is called the second major frequency,and the ratio between the two will show a decreasing trend with the decrease of the inhomogeneity of the particle volume inside the test specimen,(5)In the study of the relative calm period of acoustic emission,the calm period was defined by using the relative strength index,and it was found that the calm period didn't appear in the test of the A-type specimens.The inhomogeneity of internal particle volume in rock material affects the appearance of relative calm period.At the same time,it was found that the volume inhomogeneity of materials had no significant effect on the percentage of initial stress during the calm period,and there was no obvious regularity between the ratio of the calm period consumption and the time consumption of the stress reach peak and the internal particle volume heterogeneity of the rock-like material.