Mechanical Analysis of Water-Infusion Softening Method in Preventing Thick and Strong Roof Fall Accident around Coal Face

摘要

Roof fall accident, sometimes accompanying with rock burst, will occur where thick and strong roof strata (key strata) around a long wall coal face is not per-treated properly. Water-infusion softening method, only suitable for some certain condition, can be used to prevent the accidents effectively. On the base of borehole columnar section, geological condition and coal mining method of a mine, mechanical models are constructed and discussed by strength of materials. A composite beam formula is proposed to estimate the initial fracture distance of softened key strata. The caving and support pressure, both of softened and un-softened key strata is simulated by using RFPA software. It is evident that the water-infusion softening method is effective in roof control of the thick and strong roof strata.