Coal Pillar Design by Numerical Simulation to Protect an Inclined Tunnel

A finite element model simulation was conducted to evaluate the influence of coal mining on the performance of two parallel 7.3 m diameter inclined shield tunnels located approximately 15 m above a coal seam in China. The tunnels will be excavated by a tunnel boring machine and supported by a segmented concrete liner; this is the first application of this method in a coal mine in China. The 2D finite element model was constructed to study the influence of the coal mining on the stresses and displacements in the tunnel liner. The modelling was also performed to determine the allowable distance that mining could encroach on the tunnel location and thus the optimal size of the coal pillar to leave below the tunnels.