| Abandoned resources in thick coal seam have considerable reserves and are widely distributed.It is an important part of the recovery and utilization of coal resources integration area.Effective development and utilization of abandoned coal resources is of great significance to improve the recovery rate.Based on the geological conditions in the destroyed area of small thick seam kiln and around the different roof structure conditions of the fully mechanized top coal caving face,this paper makes a systematic study on the surrounding rock control of the abandoned coal resources by means of theoretical analysis,simulation test and field measurement,and further enriches the surrounding rock of the abandoned coal stope.The control theory has practical guiding significance and theoretical value for guiding the practice of Remnant Coal recovery,promoting the efficient utilization of coal resources and sustainable development of coal in China.The main achievements are as follows:(1)Based on the physical and mechanical parameters of coal and rock,the shape of goaf and the characteristics of roof caving,the structure of coal and rock strata before mining in fully mechanized top-coal caving face is divided into "residual goaf roof not caving","residual goaf roof part caving","residual goaf roof fully caving" and "residual goaf roof caving".There are 4 types of "falling" and "residual coal pillars".(2)The regularity of strata behavior in fully mechanized top coal caving face with thick coal seam is measured and analyzed.The results show that: Ⅰ there are obvious step difference and time difference during the weighting period of fully mechanized top coal caving face,and the influence range,duration,working resistance of support and dynamic load coefficient of weighting at different positions are different;Ⅱ influenced by roof goaf,the basic roof of fully mechanized top coal caving face is prone to lead fracture;Ⅲ roadway deformation and breakage;The main bad forms are broken and caving of top coal,failure of slice and support structure,and the deformation quantity and rate of roadway under residual coal pillar are larger.(3)The mechanism of roof control in fully mechanized top-coal caving face is revealed,the mechanical model of roof failure and instability under different coal and rock strata structure types is established,the influence of goaf filling rate and basic roof fragmentation on roof stability is analyzed,and the calculation method of support working resistance is put forward.The roof control technology system,which mainly improves the working resistance of the support,reduces the mining thickness and fills the goaf,is constructed.The control effect of the goaf filling on the roof stability and the corresponding filling parameters are defined.(4)The deformation and failure process of roadway surrounding rock in fully mechanized top coal caving face and the control mechanism and technology of roadway surrounding rock have been studied.Ⅰ the influence mechanism of roof activity on the stability of surrounding rock of roadway is revealed,and the control idea of surrounding rock is put forward,which is mainly to increase the force between fractured rock blocks and to prevent dynamic load filling cushion.Ⅱ a regional control technology scheme with anchor net cable roof type roof empty filling as the core is put forward.Ⅲ discriminating method of filling parameters needed in filling goaf at top of roadway under different roof structure is analyzed,which provides theoretical guidance for the practice of grouting engineering in goaf of roadway roof.(5)The control technology of cement foam foams empty filling roof has been implemented.The whole pneumatic system of underground slurry transportation was constructed,and the reasonable mix ratio(water-binder ratio 0.6,sand-binder ratio 3.5,cement: micro-silicon powder=9:1)was determined.The validity of the control technology of goaf filling roof was verified by borehole detection,field filling body sampling and tunnel surface displacement monitoring. |
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