| With large mining height,fully mechanized working face has large mining intensity and strong ore pressure,and the breaking characteristics and movement rules of working face roof are obviously different from those of general working face.The control of surrounding rock in stope is an important link of safe production,and the reasonable selection and arrangement of support is an important way to control surrounding rock in fully-mechanized working face with large mining height.Taking110301 high mining height fully mechanized mining face of Jinjiaqu Coal Mine of Ningxia Coal Industry Company of National Energy Group as the research object,this paper adopts theoretical analysis,industrial test,numerical simulation and field measurement and other research methods to study the overhanging rock breaking and movement characteristics,the law of ore pressure development and the key technology of support selection in working face.The main research contents are as follows:(1)110301 working face is the first mining face of Jinjiaqu Coal mine,which has the characteristics of large mining height,large dip Angle and multiple faults.The roof strata have weak anti-flooding ability,low strength and instability,and it is easy to fall cycle to pressure the roof,and the mine support is more difficult.According to the judgment theory of key strata,it is judged that the key strata of overlying rock in working face is the second medium grained sandstone layer above coal 3,and the basic top limit span and periodic breaking distance of 110301 working face are calculated.(2)Taking 110301 working face as the research background,the failure and instability law of overlying rock was studied and analyzed,and UDEC2 D numerical calculation model was established.The direct roof caving and basic roof breaking characteristics were analyzed in the advancing process of working face,the overlying rock displacement and plastic failure zone range were obtained,and the distribution law of abutment pressure of working face was revealed.The peak value of abutment pressure and its influence range are determined.The numerical simulation of FLAC3 D was carried out to study the changes of vertical stress,roof collapse and vertical displacement during the advancing process of the working face,and to reveal the variation law of the subsidence area of the overburden.(3)The relationship between the overall stiffness of the support and surrounding rock system and the stiffness of the direct roof and the support is established.From the infinite stiffness of the direct roof,zero stiffness and ordinary stiffness,different working states of the support are discussed,such as given load and given deformation.The influence of hydraulic support stiffness on direct roof deformation is analyzed when the basic roof deformation is constant.The force model of the support on the working face with large dip Angle is established,and the stability of the support is analyzed from the sliding and toppling aspects.The minimum working resistance required by single and group supports to resist toppling and sliding is discussed in the case of roof connection and no roof connection.(4)According to the geological and mining technical factors of the working face,the evolution law of pressure and displacement in the mining process is analyzed theoretically.Through the field observation of support pressure,roof displacement and the actual situation of the site,the activity law of the roof overburden and the adaptability of the support are analyzed,and the rationality of the selection of supporting equipment is further verified,providing a theoretical reference for the production practice. |
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