标题：EXPERIMENTAL STUDY OF CORRELATING THE ACOUSTIC VELOCITY AND THE PHYSICAL-MECHANICAL PROPERTIES OF COAL UNDER VARIED STRESS BASED ON CLEAN COAL ENERGY DEVELOPMENT CONCEPT
摘要：Natural coal is one of the main energy sources in common use. The development of coal resources is easy to produce a large number of waste water and other wastes, and then cause environmental pollution. The characteristics of coal seam porosity and perm eability are directly related to the effect of coal m ining and environmental protection. Acoustic technology has been gradually applied to reservoir evaluation of oil, gas and coal resources. To explore the correlations between the acoustic velocity of coal and its mechanical-physical properties, we designed a core holder to conduct wave velocity and seepage parameter measurements w ith effective stress variation. These measurements, combined w ith computed tomography (CT) scanning results, were analyzed to identify the influence of native coal bedding structure, sample density, and loading stress. The results show that the acoustic velocity of coal has a strong relationship w ith the test direction (coal bedding structure), sample density and sample strength; both the longitudinal wave (P-wave) and transverse wave (S-wave) velocities increased w ith the sample density and strength. The P-wave and S-wave velocities are much higher parallel to the bedding planes than they are perpendicular to the bedding planes; parallel to the bedding planes, the velocity along the strike direction is more significant than that in the inclination direction. The S-wave is much more easily influenced by the bedding structure than the P-wave is. A dditionally, the P-wave velocity increases significantly w ith increasing confining pressure, w hile the perm eability and porosity decrease w ith increasing confining pressure exponentially. The acoustic velocity and porosity are negatively linearly correlated, w hile velocity and perm eability have a negative nonlinear correlation. Visualization of the coal structure indicated that the observations of the dynamic closing of internal cracks and pores in the coal agrees w ell w ith the acoustic and seepage test results.
关键词：Clean coal energy concept;environmental pollution;coal structure;acoustic wave velocity;seepage parameters
