Research on Combined Tests to Entry Disturbed Zone (EDZ) of Rock Masses in Steep Coal Seams

摘要

For high production of raw coal in steep coal seams, it is crucial to obtain engineer demands by enhancing section height in horizontal caving. However in-situ operations copious methods like pre-blasting was always needed to broken top-coal which was difficult to excavate commodiously and safely. Explosive wave caused by pre-blasting would destroy stress balance around entries, and definitely result in entry disturbed zone (EDZ) being loosen zone. Aimed to determine boundary of EDZ and keep rock mass in both entries steady, combined tests to EDZ of rock masses of head entry of +600 east-side stope of 43# coal seam was done in Wudong Colliery as research background with ground penetrating radar (GPR) and mono-hole ultrasonic wave experiment. It indicated that scope of EDZ here was 2.2-2.3m, which would be prerequisite to optimize supporting scheme in field.