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A two-dimensional numerical model of a large (1 000 m×200 m) section ofmine strata in the vicinity of seam 349 in Iongwali panel 802 in part B of the Murcki Collieryin the Upper Silesian Coal Basin,Poland,was built using the Universal Distinct ElementCode UDEC.Longwall extraction of seam 349 with roof caving was simulated in the modelover a length of 450 m.Mining-induced changes in displacements,strains and stresses inthe mine strata were investigated.Under the assumptions that (1) methane.bearing strataoccur 15.6 m beneath seam 349 and include seam 350 and the strata lying beneath,and(2) the methane reservoir pressure is equal to 2 MPa,a fully coupled mechanical hydraulicanalysis was performed in which joint conductivity was dependent on the mechanical deformationand,conversely,the mechanical behavior of rock masses was affected by jointfluid pressure.It was shown that migration of methane from coal seams lying beneath themined seam is possible under conditions where the floor strata deform to a great extent,undergo separation,fracture and break into blocks.
A two-dimensional numerical model of a large (1 000 m × 200 m) section of mine strata in the vicinity of seam 349 in Iongwali panel 802 in part B of the Murcki Colliery in the Upper Silesian Coal Basin, Poland, was built using the Universal Distinct ElementCode UDEC.Longwall extraction of seam 349 with roof caving was simulated in the modelover a length of 450 m. Mining-induced changes in displacements, strains and stresses inthe mine strata were investigated .Under the assumptions that (1) methane.bearing strataoccur 15.6 m beneath seam 349 and include seam 350 and the strata lying beneath, and (2) the methane reservoir pressure is equal to 2 MPa, a fully coupled mechanical hydraulic analysis was performed in which joint conductivity was dependent on the mechanical deformation and, conversely, the mechanical behavior of rock masses was affected by joint fluid pressure. It was shown that migration of methane from coal seams lying beneath themined seam is possible under conditions where the floor strata deform to a great extent, undergo separation, fracture and break into blocks.