Characteristics of Deformation and Failure of Deep Coal Seam Floor Affected by Fully Mechanized Mining

Abstract

This paper dealt with the deformation and failure characteristics of a mining-affected deep coal seam floor by selecting the fully mechanized coal-mining face of the coal mine in the east of Jining City, Shandong Province, China. We numerically simulated and experimentally tested the variation laws of the strain increment with the mining face advancing and the distribution characteristics of the floor's plastic zone at different depths. The results showed that (1) the failure depth of the mining-troubled floor was between 18 and 20 m and the degree of floor failure would further aggravate with face advancing and floor unloading, and (2) the impact of mining pressure on the coal seam floor showed obvious leading and lagging characteristics, and thus its impact region in the coal seam floor could be divided into the elastic and violent disturbance regions. In addition, we numerically simulated and analyzed the mechanism of deformation and failure of the mining floor and showed that simulated results were consistent with the in situ measured results. This study not only provided important information on the roadway supporting of fully mechanized mining tunnels for the prevention of rock bursts, but also provided an important reference value for coal mines with similar geological conditions.