The coal pillar design method for a deep mining roadway based on the shape of the plastic zone in surrounding rocks

摘要

Classic coal pillar design theory is inapplicable to engineering practice involving the design of coal pillars for deep roadways. Aiming at this problem, the current research investigated the shape of plastic zones in the rocks surrounding a deep mining roadway based on theoretical analysis, numerical simulation and field tests. On this basis, the influence of coal pillar dimensions on the principal stress direction of the stress field in the surrounding rock zone, the distribution pattern of the plastic zone and the stability of roofs of a deep mining roadway was investigated. In addition, the study revealed the mechanical essence of the coal pillar dimensional influence on the shape of the plastic zone in the rocks surrounding a deep mining roadway. The result showed that a butterfly wing-shaped plastic zone appeared in the strata at different roof positions owing to the coal pillar dimension causing a change in principal stress direction. When the butterfly wing-shaped plastic zone was located in the strata of the coal pillar of the roof, the influence on the stability of the roof was the lowest, while it was the greatest when it was located in the strata in the middle part of the roof. On this basis, the study proposed a coal pillar design method for deep mining roadways based on regulating the shape of plastic zones in the rocks surrounding the deep mining roadway: this provides a new theory and method for the optimal design of the coal pillar dimension for deep roadways.