Comprehensive study on a collapse column in Kongzhuang coal mine

Geological and geophysical theories and methodologies were applied to study a broken up body in Kongzhuang Coal Mine, which is suspected to be collapse column but maybe fault belt also. The purpose is to discover its features, formation and evolution history and its endangerment to coal mine running. Electric prospecting results indicate that the body is 70 m×40 m irregular ellipse in horizontal and about 150 m height slightly sloping column in vertical cross section. This means it is not a fault belt but a collapse column. Stratigraphy, petrology, sedimentation and structure geology studies have been conducted. The collapse column has the characteristics of dry falling accumulation, which is filled by broken rocks of Shanxi, Xiashihezi, Shangshihezi and Shiqianfeng Formation loosely almost without cementation. The collapse column was formed at late of the Paleogene Period, on the background of strong extensive geo-stress field. Its formation is the result of comprehensive actions of factors such as strata, lithologic characters, structure movement and underground water. Considering the well water transmissibility and loose structure of the collapse column, further prospecting and relative water and roof falling prevention countermeasures must be conducted.