Thus, based on the analysis of overlying strata movement and the flow characteristics of gas from adjacent seams, we propose an adjacent seams gas drainage technique of a large-diameter blind shaft joined to the high-level gas drainage roadway (LDBS-HGDR) for the initial mining phase.
Based on the movement characteristics of overlying strata at the LTCC face, Yan (1996) introduced a mechanical theory of limited deformation and proposed a balance structure of macro continuous "compressed arch beam" of overlying strata at the upper location.
The proposed method is based on the assumption that both the caprock and the overlying soil behave plastically under compression upon reaching the yield criterion without brittle failure.
In academic circles at present, for goaf closure, researchers mainly perform a theoretical analysis of the fissure development of overlying rock strata based on the "three belts" assumption.
In the waveform calculations, we considered two velocity models: a standard model with only the low-velocity subducting crust and a model that additionally involves thick low-velocity materials overlying the Pacific slab based on the result of Kita et al. (2010, 2012).
Based on the study discussed above, a "cantilever beam articulated beam" structural model for overlying strata at a LLTCC face has been developed, shown in Fig. 9.
Based on the different mining boundaries at different mining areas, the main roof and overlying strata may form four types of 3D structures after caving, including type "θ", "O", "S" and "C".
Based on the findings from the field monitoring and numerical modelling, a three-dimensional annular-shaped overlying zone along the perimeter of the longwall panel is identified for optimal methane drainage during mining.
Based on the findings from the extensive field monitoring and numerical modelling studies, a three-dimensional annular-shaped overlying zone along the perimeter of the longwall panel was identified for optimal methane drainage during mining.
