Features of Coal Bursts in Miike Mine and Considerations about its Mechanical Factors

Study on coal burst (1st Report)

Abstract

The purpose of this study is to investigate the mechanism of coal burst and the effective methods for destressing and strata control in order to conquest the coal bursts. In this paper, we study on the actual features of coal bursts in Miike mine and the geological characteristics in the locations.
The coal bursts have occurred many times along the longwall face of a flat coal seam, 1.8m thick. But every one of them is located in the limited area shown in Fig. 1. We can classify them by the magnitudes of damages likely shown in Table 1 and 2. Up to the present, the coal bursts have occurred anywhere in the face, but severe in the rise part of face. This may be caused by the concentrated stress in the intersection of the pressured zone in front of the face and the abutment of old working.
The important geological preconditions are the very thick sandstone in the roof, lying directly on the seam without faults, and the floor sandstone which is 2-3m thick and under which there is a locally developed coal seam, 0.4m thick, and a stiff sandstone, 6m thick, they are shown in Fig. 10-12. Statistically we conclude that the occurrence of coal bursts in this area closely correlates with the thickness of floor sandstone. Under 2m thick, the floor only swells along the levels and over 3m thick, the hazard of coal burst is removed. Other geological factors which may play a part in assessing the hazard of coal burst is the local fluctuations in coal seam thickness.