PHYSICAL AND MECHANICAL PARAMETERS OF BOREHOLE HYDRAULIC MINING OF NONG'AN OIL SHALE

The experiments on physics and mechanics of borehole hydraulic mining were designed to determine mechanical characteristics of mined oil shale. Oil shale of Nong'an deposit belongs to slightly weathered and relatively complete rocks. Oil shale beds are characterized by a very definite discontinuity in both horizontal bedding orientation and vertical bedding direction. Compressive strength, tensile strength, Poisson's ratio and other data characterizing oil shale beds in different directions in the Nong'an min- ing site were obtained and compared. The direction of borehole hydraulic mining was determined. The vertical bedding direction to break oil shale was considered to be better, because strength in this direction is low, rock mass integrity poor, and the degree of weathering more pronounced. The diameter of borer nozzle, dynamic pressure, maximum caving capacity and other parameters needed for borehole hydraulic mining were selected.