Movement Evolution Of Failured Overburden Infullenced Obiviously To The Ground Pressure Around Working

The dissertation has studied in detail the main forms of failured overburden including separation, crevice, penetrating crack and collapse, and the processes of overburden failuring above longwall working face in the coal mine by using the method of equivalent material model test, numerical analysis and test in situ.Guided by the theory of underground pressure dominated by the movement of overlying strata, considering the engineering demand of underground control and the gravity transmitting feature of failured overlying strata along the working advance, the dessertation puts forword originally "three failured strata zones "in which the movement of higher strata above working obviously influence the face ground pressure manifestation. In the three failured strata zones model, the failured overburden is divided as follow:collapsed zone (S4) - which consists of collapsed strata, penetrated-crack zone(S3),which is composed of broken strata without obvious displacement, the seperated-crack zone(S2) in which the cross crevice and speration between strata has already existed. All the three zones are always in the dynamic development state,they can affect and transfer inherent among them.Based on the internal evolution of penetrated-crack and its influence to the other two zones, the dissertation demonstrates firstly that the penetrated crack zone is the "key failured strata zone " of the three zones.Therefor the overburden failuring can be divided into four stages according to the development of penetrating-crack zone initially,which are seperation repressing stage, crack-penetrating stage,striking movement stage and relative stabilization stage. Further the failure limits of overburden for the four stages along the strata vertical section and the working advance direction , the fore-abutment pressure distribution owing to the movement of failured strata are studied. It is also show that the maximum abutment pressure occurs while the broken strata in the penetrating-crack zone, ie, the key failured strata zone, take movement obviously.The thesis differentiating "three failured strata zones" , the evolution and its distribution of abutment pressure manifestation are also shown and clasified by the test in situ of forms and range about higher failured overburden in fully mechanized sublevel caving in Yanzhou coal Mines.All these results give a good basis for the apply of thesis of "three failured zones " in practical control of the failured overburden.