Research On Mine Pressure And Overlying Strata Movement In The First Coalface Of The Huojitu Mine

The coal seams in the Shendong Minefield are embedded shallow,overlying only by thin rock strata and relatively thick aeolian sand layers,and their occurrences are stabile. In such conditions,the excavation of coal has obviously features. In order to make production high efficient and safety,the first coalface,No.5 longwall coalface on the Huojitu Mine is selected to observe the mine pressure and strata movement,whose rules are summed up,and can guide the excavation work in the same conditions.The first caving interval of immediate roof is 17 to 18 meters,and the first weighting interval of main roof is 43 to 52 meters. When the immediate roof firstly caves,the emergence of mine pressure in coalface is not obviously;while the main roof firstly caves,the emergence of mine pressure in coalface is obviously. The periodic interval of main roof is 13 to 18 meters. During the periodic weighting of main roof,the sinking velocity of roof increases obviously,but the total sinking number is not too large.When the top of coalface occurs very thin rock strata (e.g. valley),the cracks of roof directly connect to the land surface,so we must increase the excavation velocity and block off the surface cracks in time.The time of excavating coal seam under the valley should avoid at the rainy season.