Comparative analysis of Overburden Strata Movement in Fully Mechanized Top Coal Caving Mining in Entire (Sub) layer of Ultra Thick Seam

摘要

Reasonable determination of entire layer or sublayer mining method is the key factor of safe and efficient mechanized caving mining of 14.0～28.0m ultra thick seam, numerical simulation on the entire (sub) layer coal caving mining by the FLAC3D, studying the stress and displacement variation of overburden strata, combining the underground pressure theory, comparative analysis on the calculation results. The results show that entire (sub) layer mining roof stress, movement contours are presented in a semi-elliptical arch morphology, indicating the existence of a high arch structure overburden formations, mining process appears roof tensile destruction, but the entire layer caving tensile stress intensity is lower than sublayer caving. When advancing the same distance, entire layer caving puts a greater impact on the overburden strata than the sublayer caving, has some features such as big range of influence and extent, small roof pressure, lead abutment pressure forward from grand, short time of achieving full extraction, etc.