Ultrasonic and CT scanning analysis of coal-rock mass under the primary bedding structure
In order to study the influence of the primary bedding structure on wave velocity and mechanical properties of coal-rock mass,multilayer and multi-directional ultrasonic and CT scanning tests were carried out in laboratory.It also aims to improve the accuracy,rapidity and convenience of obtaining the wave velocity and mechanical parameters of coal-rock mass in laboratory.Based on the ultrason-ic test,the characteristics of wave velocity and wave velocity ratio at different layers of coal-rock mass under the primary bedding dip angle were obtained.Combined with CT scanning and 3D reconstruction technology,the calculation method of CT gray mean value in dif-ferent layers was proposed by using the data of the gray frequency of coal and rock.And the variation law of gray value and coal and rock content of coal-rock mass in different layers under different primary bedding dip angle was obtained.Meanwhile,the relationships between CT gray mean value and wave velocity,mechanical parameters of coal-rock mass were established.Considering the effect of bedding dip angle and the content of coal and rock,the calculation model of longitudinal wave velocity of coal-rock mass was constructed.Then the correctness of the model is verified by comparing the test data.The results show that:① the wave velocity and wave velocity ratio of coal-rock mass with primary bedding are linearly related to bedding dip angle;with the increase of bedding dip angle,the longitudinal wave ve-locity of coal-rock mass decreases linearly,while the distribution range of wave velocity ratio expands;② the mean wave velocity of CT is linearly correlated under different bedding dip angles,and the wave velocity of coal-rock mass increases linearly with the increases of CT gray mean value;③ the density of coal-rock mass increases linearly with the increase of CT gray mean value,the dynamic elastic modu-lus and shear modulus of coal-rock mass have third order polynomial relationships with the mean value of CT gray level,and they tend to increase with the increase of the mean value of CT gray level;④ compared with the bedding dip angle,the wave velocity of coal-rock mass is more sensitive to the coal and rock content,and the wave velocity changes largest during the content of coal and rock similar.
万方数据
维普
