Abutment pressure distribution pattern and size optimization of coal pillar under repeated mining: a case study

Abstract

Abutment pressure distribution is the decisive factor affecting the stability of coal pillars, which has an important significance in realizing safe and efficient mining. In recent years, many working faces adopting double-roadway arrangement have appeared in the western mining areas in China, which makes coal pillar abutment pressure complex under repeated mining. In order to reveal the distribution pattern of coal pillar abutment pressure under repeated mining, the evolution of a stress field of surrounding rock was analyzed by a numerical method based on the actual situation of a double-roadway arranged mining roadway in Longde Coal Mine, and the distribution characteristics of coal pillar abutment pressure were revealed. The reasonable width of the section coal pillar was given further. The research results showed that (1) the surrounding rock stress is transferred to the working face coal body and section coal pillar between roadways under the influence of mining advance the working face, while the stress is transferred to the section coal pillar between roadways under the mining influence behind the working face. The presence of goaf in the upper segment makes the stress distribution of surrounding rock more complicated. (2) The distribution of coal pillar abutment pressure shows a staged change. The influence of mining advance the working face on the peak abutment pressure is notable, which highlights the significance of temporary reinforcement support in the advanced section of the working face. (3) After the mining of the upper working face is finished, the yield damage width of the coal pillar on the side of the goaf was about 4.0 m. During the second mining period, the yield damage width of the coal pillar was totally about 7.0 m. (4) Taking into account factors such as safe production and economic rationality, it was finally determined that the reasonable section coal pillar width is 12.5 m for this mine.