Numerical Study of Stability and Connectivity of Vertical Goaf Drainage Holes

During underground longwall coal extraction, overburden strata deformation may result in vertical goaf drainage holes, which are drilled in advance of mining for tail gate gas management, to fail. The performance of these vertical goaf drainage holes is controlled by mine design parameters and local geomechanical properties. This paper investigates the use of advanced 3D finite element modelling and 2D discrete element modelling simulation techniques to understand the fundamentals of vertical goaf drainage hole failure mechanism due to strata shear at a currently operating gassy Australian mine site. Finite element modelling is used to investigate the location of high shear in the overburden strata at the vertical goaf gas drainage hole region during longwall mining and the discrete element modelling is used to examine connectivity from the goaf region to the goaf-gas drainage system.

Automated summary

This study investigates the failure mechanism of vertical goaf drainage holes in a operating Australian mine due to strata shear during longwall mining, using advanced 3D finite element modelling and 2D discrete element modelling simulation techniques. Finite element modelling is employed to locate high shear areas in the overburden strata at the vertical goaf gas drainage hole region, while discrete element modelling is used to analyze connectivity from the goaf region to the goaf-gas drainage system.