Forecast of Geological Gas Hazards for “Three-Soft” Coal Seams in Gliding Structural Areas

Gas outbursts from “three-soft” coal seams (soft roof, soft floor and soft coal) constitute a very serious problem in the Ludian gliding structure area in western Henan. By means of theories and methods of gas geology, structural geology, coal petrology and rock tests, we have discussed the effect of control of several physical properties of soft roof on gas preservation and proposed a new method of forecasting gas geological hazards under open structural conditions. The result shows that the areas with type III or IV soft roofs are the most dangerous areas where gas outburst most likely can take place. Therefore, countermeasures should be taken in these areas to prevent gas outbursts.