Study On The Stress Field And Movement Laws Of Overlying Strata In Gently Inclined Multi Coal Seams Mining

Based on characteristics of the associated mining No.6 and No.8 coal seams in Xieqiao Coal Mine, comprehensive research methods combining theoretical analysis,three-dimensional numerical simulation and in-situ measurement are carried out to investigate the distribution of the complicated stress and displacement field, failure mechanism, displacement and movement laws and the interaction influence between upper /lower coal seams. Firstly, a systematic analysis has been done on the overlying strata deformation failure process and the interactive space-time relation in the multi coal seams. The heights of caving zone and fractured zone of multi coal seams mining are obtained. Subsequently, through FLAC^3D establishing numerical simulation model of multi-seams mining, the paper analyzes the stress field and deformation characteristics of overlying strata and the influence scope in the upper coal seam caused by the lower coal seam mining. In addition, this paper utilizes the elastic thin plate theory, the elastic-plastic mechanics knowledge to resolve the transferring characteristics of the stress and the damage depth in coal seam floor with the complex effect of the upper seam mining pressure. Meantime, the stress field and deformation failure characteristics of coal seam floor rock mass are obtained by means of numerical simulation.The results of numerical simulation reveal that the strata deformation rules, the rational space-time relation between upper /lower coal seams and positioning pattern of roadway during multi coal seams advancing. Compared with theoretical analysis, the numerical simulation reflects the dynamic progressive process of stress redistribution and displacement laws of overlying strata.Finally, according to geological conditions of Xieqiao Coal Mine, in-situ measurements of the pressure behavior and the roadway surrounding rock deformation in the lower coal seam working face are conducted. The results in this paper provide a theoretical basis for safe mining of gently inclined multi coal seams and the confirmation of rational roadway location. At the same time the results also provide beneficial lessons for multi coal seams mining in other similar geological conditions.