Numerical Estimation of Suitable Distance between Two Adjacent Panels’ Working Faces in Shortwall Mining

Abstract

Determining a suitable distance between two adjacent panels’ working faces (DBTF) is an important issue that should be considered in underground mining methods. A suitable DBTF causes a decrease in stresses on the pillar, reduces the width of the pillar, and controls the ground subsidence. The main purpose of this study was to determine the suitable DBTF in shortwall mining of the Tabas central coal mine. For this purpose, at the beginning, an algorithm is presented for numerical modeling. In this algorithm, front abutment stresses first and then side abutment stresses are evaluated on the chain pillar. Numerical modeling is performed by finite-difference method software in different distances of P5 and P6 panels’ working faces (5–45 m). The result of this research shows that the front abutment stress on the chain pillars is not different for a distance of 25 m or more. Moreover, by increasing the distance up to 25 m, the side abutment stress in the vicinity of the P5 panel face is decreased on the chain pillar and is increased on the chain pillar in the vicinity of the P6 panel’s working face. However, when the DBTF increases to 30 m, the lowest side abutment stresses are applied on the chain pillars and then increased for greater distance. It can be concluded that a suitable DBTF in the Tabas central coal mine is 30 m.