Study On The Ovorlying Rock Failure Of The First Caving Ming Face Of Similar Shallow Thinck Coal Seam In Zaoquan Coal Mine

Near ten's remaining years, the more depth study of shallow coal seams of less than 150m found the law of failure of overlying rock in typical shallow coal seams. However, the studies of failure of overlying rock is relatively less in similar shallow coal seams of less than 150m with thick base rock and thin relax layer. The law lack complete and integrity cognition with the cracking of rockmass and move of terrance all the same. So ,when the near shallow coal seams were cosmically mined in the northwestward area with scarcity water resource and flimsy entironment, holding the law of failure of similar overlying rock was very importante change and direction significance toward safety produce of coal mine and protection of ground water resource.The depth of imbedment is from 100m to 200m with the 2nd coal seam of first working face of Zaoquan mine of Lingwu mining area. In this paper, the geological character was analysed. The date of mine press was collected..The law of failure of overlying rock was studied. At she same time, the simulating esperiment of similitude material simulated mining of working face and studied the law of failure of overlying rock and process of dynamic development. Finally, the destroy mechanism of overlying rock was explanation and exploring.The study indicate that periodic weighting was not distinctness. The work resistance of bracket was nearly work resistance. The height of control roof of bracket was less than from 6 to 8 times mining higt.The middle part roof distance of press was small, but both ends roof distance of press was big. Through the simulating experiment of similitude material, the overlying strata formed"three zone"after mining the first delamination. The number 4 moisture layer was destroyed. The height of"three zone"and sinking quantity of the earth's surface were measured. The"three zone"became"two zone"after mining the second delamination. The number 3 moisture layer was destroyed. Through the theory of key layer confirm 4 key layers of overlying rock. Through analyse of theory and process of experiment consider number 1 and 2 key layers were destroyed after mining the first delamination and number 3 and 4 key layers were destroyed after mining the second delamination. And that through theory presented the process and mechanism of failure of overlying rock.The result of study have direction meaning for the minging of work face of nearly similar shallow coal seams.