Research On The Mechanism Of Strong Rock Pressure And Roof Control In Island Working Face Of Shuiyu Coal Mine

With the continuous exploitation of coal resources,the mining of resources in major mining areas in China,especially those with long service life,has gradually shifted to areas with poor geological conditions such as deep coal seams,re-mining,isolated islands,and corners,and mining conditions have become more complex.The pressure of fully mechanized caving mining also tends to be obvious and severe,which is likely to cause roof fall,slabs,equipment damage,and even casualties,and may even cause serious disasters such as gas and coal dust explosions and rock bursts.The safety production situation is very severe.Shanxi Fenxi Mining(Group)Limited Liability Company Shuiyu Coal Mine 6115 fully mechanized caving face is faced with unfavorable conditions of goaf on both sides and goaf of the upper 9# coal seam.It is of great engineering significance to study its underground pressure behavior and roof control technology.In this thesis,through laboratory tests,theoretical analysis,numerical simulation research and field measurement methods,the mechanism of strong underground pressure and roof control technology for fully mechanized caving mining in thick coal seams are studied.The main conclusions obtained are as follows:(1)The overlying strata on the 6115 fully mechanized caving face includes two key layers: the first key layer 6# rock layer and the second key layer 14# rock layer.The first key layer collapses when the working face advances 40 m,and the second key layer collapses when the working face advances 80 m.The height of the collapse zone was about 15.38?19.23 m.(2)The coal seam structure of 6115 fully mechanized caving face is complex,with developed cracks,which is prone to roof spalling,and the coal slab slab will induce roof leakage.Timely and effective control of the end face distance is the main countermeasure to prevent the coal slab slab and roof falling.(3)The stress field and displacement field in the mining process of 6115 fully mechanized caving face are calculated numerically,and the distribution curve of the coal wall's advanced abutment pressure and the stress concentration coefficient,as well as the key control area and direction are determined.The factors affecting the stability of the roof and coal wall are analyzed,and reasonable control parameters are studied: the end face distance is controlled within 0.5m,and the beam end distance is controlled within 0.3m.The working resistance of the hydraulic support is not less than 7000 k N,and the inclination angle of the front pillar of the hydraulic support is controlled around 83°.(4)The mine pressure observation plan for 6115 fully mechanized caving face was formulated and the mine pressure observation was carried out.The results of mine pressure measurement showed that the initial pressure step distance of 6115 face was about 35.5m,and the initial pressure appeared strong and the step distance for cycle compression is 15.9m.During compression,the coal wall has a wide range of slabs and the depth of the slabs is 0.2-1.3m.The roof management measures such as timely shifting of supports,reduction of cross-section distance,and strict support setting force have been adopted to ensure 6115 safe production of fully mechanized caving face.The paper has 40 maps,8 tables,and 66 references.