... the conoept of equivalent initial stress. The radial di splacement ari sing adja-- cent to the tunnel face when a oircular tunnel is excavated in rook whioh has arbitrary initial stress in isotropical and homogeneous materials, has been clarified (Fig.3) from the results of axial symmetry FEM analysis...

... and maintenance of the longwall workings. metals & mining load-bearing capaoity face support operation diagram whioh immediate roof strata cohesive roof strata model test seam root strata rock mass Prop construction longwall face roof strata solid coal strata functional relationship...