The Overlying Strata Structure And Movement Laws Of Full-Mechanized Caving With The Thick Coal Seam Immediate Roof Invaded By Lamprophyre

The processes and technologies in coal-mining have been improved in recent years,which promote the efficient mining of the thick coal seam.The thickness has reached to 7m with the technology that can mine the full height of the coal seam at one time,while it has exceeded 20m in full-mechanized caving mining.The most important reason of selecting full-mechanized caving mining in the Coal Mine of Datong Co.ltd is that the thick coal seam is invaded by gray-yellow layered lamprophyre.However,the data taken from the production field have showed the abnormal strata behaviors in the full-mechanized caving mining when the thick coal seam is invaded by gray-yellow layered lamprophyre.Meanwhile,the traditional theory of mining pressure and strata control can no longer guide production of the efficient mining.What is more,it is of significance to select the hydraulic support reasonably in the full-mechanized caving mining of thick coal seam for the efficient mining.As known to everyone,the reasonable selection of hydraulic support in the full-mechanized caving mining of thick coal seam is supported the theory of rock pressure and strata control and the core of rock pressure and strata control is the structure and movement laws of overlying strata.Therefore,the study of the structure form and movement laws of overlying strata will provide theoretical basis and technical support for the full-mechanized caving mining.From the perspective of the property of lamprophyre,the structure form and movement laws of overlying strata of full-mechanized caving mining when the thick coal seam is invaded by gray-yellow layered lamprophyre based on indoor experiment,theoretical analysis and numerical simulation.The main research contents are presented as the following ones:(1)The invasion mean,characteristics,mechanism together with the effects of lamprophyre are the research focus based on the the thick coal seam is invaded by gray-yellow layered lamprophyre in the Coal Mine of Datong Co.ltd.The results show that the coal seam is invaded in the layer form by the by gray-yellow lamprophyre.With the difference of coal seam and different invasion area,the number of the layered lamprophyre are distinguished.The number of the layered lamprophyre can reach about 15,and the maximum thickness is about 4.6m.When the hot magmatite invaded into the coal seam,not only the metamorphosed coal can generate,but also the primary joints that are vertical or near vertical to the bedrock direction.(2)Aiming at explore the uniaxial compressive mechanical characteristics and mechanism of the lamprophyre without soaking in water and the one soaking in water for a few days,the indoor experiment about the characteristics and mechanical properties of lamprophyre are conducted and the experiment about the Watering properties is designed.The results indicate that:comparing with lamprophyre without soaking in water,the uniaxial compressive of lamprophyre soaking in water for a few days will greatly decrease.The change of the microcosmic structure and the amount of mineral composition are the main reason of the mechanical-property change.(3)Together with the indoor experiments and the numerical simulation results,the mechanics model of the overlying strata is established,which can vividly present the structure and movement laws of overlying strata when the bottom immediate roof is invaded by gray-yellow layered lamprophyre.The results show that:when the immediate roof is invaded by lamprophyre,the"cantilever beam" structure will generate.What is more,with the advance of face,the structure of top hinged beam and bottom cantilever beam as well as the structure of top voussoir beam and bottom hinged beam will generate.(4)Combined with the real invasion condition of lamprophyre,the mining model of different thickness of the lamprophyre,different invasion position and the lamprophyre soaking with water are established individually based on the software named UDEC.With the numerical simulation and theoretical analysis,the influence of thickness,thickness of the lamprophyre and the softening characteristic on the structure and movement laws of overlying strata can be conclude,which will provide a serous of theory for the full-mechanized caving mining when the thick coal seam is invaded by gray-yellow layered lamprophyre.