Mechanism of the dynamic pressure caused by the instability of upper chamber coal pillars in Shendong coalfield, China

摘要

In Shendong coalfield, severe support failure accidents caused by the dynamic pressure occurred frequently when longwall faces extracting the lower coal seam progress below the chamber coal pillars. These incidents largely threaten the personnel safety and regular operations. The rationale of the dynamic pressure has been investigated based on the movement law of the overlying strata. Experimental and numerical simulations of a longwall face in Shigetai coal mine agree well with the qualitative explanations. It is shown that the failure of the chamber coal pillars causes the sudden break and even rotation of the key strata, thereby leading to strong dynamic load that crushes the supports in the longwall face. Several guidelines have been proposed to prevent the occurrence of the dynamic pressure, the capability of which has been demonstrated by in situ practice in two longwall faces in Shendong coalfield.