Experimental Study On The Acoustics Characteristic Of Layer Rock And Rock Damage Under Explosion Load

Ultrsonic diffusing speed in medium reflects physical and mechanics of medium. Ultrsonic testing technique in rock mass medium is a new technique which has been developed during near thirty years. It realized physical and mechanics characters, structure and stress state of rock mass by testing the change of acoustics parameters of sound wave signal after penetrating rock mass, which got recognition in domestic and over seas geotechnical engineering fields.Layer rock is crude mass made of manifold different mineral, hole and cement. Under long geologic effect and complex tectonic movement, different random order of micro-and macro-pore structure were brought in rock mass, so its characteristics are very different from the single rock. The physical and mechanical properties of layer rock and the acoustics characteristic have a close relationship. It is very significant to study on rock blasting damage through the means of ultrasonic testing to explore the rock layers in different directions on the physical and mechanical properties, and layer-depth analysis of rock mass damage conditions in the blast loading.Firstly, longitudinal wave speed of limestone, which has the layer structure, are tested by RSM-SY5 sound wave test apparatus, and the physical and mechanics of rock are analyzed by the way of studying the nature longitudinal wave speed; Then explosion-in hole compression test are carried out, and after then the blasted rocks are made of the sample to observe, and the different damage characteristics of different directions are studied.Test results show that the layer rock have significant anisotropy. In parallel to bedding and vertical stratification directions, the longitudinal speed, the spectrum characteristics are very different, which reflects the stratification of rock in different directions on different physical and mechanical properties. To some extent, rock acoustic velocity, waveform and spectrum characteristics have a good correlation with the characteristics of the rock anisotropy, which is also closed related with the damage features of the blasted rock.Blast loading test results show that the load in different directions result in different damage characteristics of the layer rock. Along the high-velocity direction of loading, crack rock have more damage and larger damage regional scope, and the cracks develop with a good direction; Along the low-velocity direction of loading, crack rock have less damage and smaller damage regional scope, and the cracks develop with no obvious crack direction. In addition, the differences of the longitudinal wave speed in different directions is closely related to the differences in the degree of rock damage. The more obvious the anisotropy of the longitudinal wave speed is, when loaded in different directions, eventually the damage results of the rock in all directions are in the greater difference. The acoustics characteristic of layer rocks and their characteristics of blast damage show a good correlation.