Numerical modeling of coal wall spall in a longwall face

• Longwall face spall mechanism was revealed numerically and verified by field observations. • Mechanical behaviours of coal wall were presented versus longwall face advancing. • Tensile stress concentration near the coal wall dominates the tensile splitting failure as laminas after coal wall exposed. • Shear strain bands initiating from the outer ends of tensile areas results in shear slipping failure as blocks...