METHOD OF BENCHING THICK COAL BEDS PRESENTING HIGH CRUMP HAZARD

1. An exploitation method for a thick bed of high crump hazard, whereas during the expoitation of the roof layer and while creating a fall of roof therein, or after finishing the exploitation, a mixture of water and silt is poured into an area bordered preferably with a side wall and with a bottom wall, and then, after settling the silt on the fall floor being the roof for a layer located beneath, water is removed off the fall of roof area, characterized in that while taking out the roof layer, preferably in front of the wall forehead in the floor in parallel lines to the wall forehead or in a perpendicular line to the forehead line, metering apertures are drilled, and then anchors with geophones are installed in those apertures, the speed of a transverse wave is metered, and after a significant transverse wave speed was found, apertures are drilled in the floor, preferably up to 100 mm diameter, preferably along parallel lines to the wall forehead, in distances of 1.5 to 3 times the machine web, and after a significant rockmass stress was found between the lines of apertures of diameters up to 100 mm, watering apertures are drilled preferably in parallel lines to the wall forehead, whereas those watering apertures have preferably diameters up to 50 mm, and then, the watering apertures are filled with water under pressure of 200 or more atmospheres, in most cases till a noticeable pressure drop or until water is visible inside the 100 mm apertures, and then speed of transverse wave is measured in the solid coal within the floor.