Abstract
Reasonable width of gob‐side coal pillar can reduce the waste of coal resources and is conducive to roadway stability. According to the distribution of internal and external stress fields at the working face, a method for determining the width of gob‐side coal pillar was proposed. The coal pillar and roadway should be set within the internal stress field, and support is provided through the anchored part and the intact part of the coal pillar. The method was used in the design of the coal pillar at No. 130205 working face of Zaoquan Coal Mine. The calculation results indicated that the width of a coal pillar suitable for gob‐side entry is 6.0 m. It is reasonable to arrange the roadway and coal pillar in the low‐stress zone with a width of 11 m. During tunnelling of roadway and stoping of the working face, the deformation of the roadway increased with a reduction in the distance from the working face. Even during stoping of the working face, there was an approximately 1.5 m intact zone in the coal pillar. This indicates that the proposed method of designing small coal pillar of gob‐side entry driving is reliable.
Highlights
With the continuous improvement of coal mining methods and the enhancement of the mechanical equipment level, fully mechanised caving has become an important mining method for thick coal seam [1,2,3]
An FLAC3D numerical simulation model was established according to the physical and mechanical parameters of coal and the geological characteristics of Zaoquan Coal Mine, as shown in Figure 4. e working face and the roadway were arranged in the central area of the model, and the grid was densely divided in the part around the roadway. e numerical model comprised 285,600 grid units. e left and right boundaries of the model were constrained by horizontal displacement conditions, and the lower boundary was constrained by vertical displacement
A method for determining the location and width of a small coal pillar was developed on the distribution of the internal and external stress fields at the working face. e method was applied to working face 130205 of Zaoquan Coal Mine
Summary
With the continuous improvement of coal mining methods and the enhancement of the mechanical equipment level, fully mechanised caving has become an important mining method for thick coal seam [1,2,3]. Aiming at the defect of traditional coal pillar safety evaluation method which regards safety factor as fixed value, Najafi et al [14] proposed a coal pillar stability evaluation method which regards safety factor as probability function. He et al [15] studied the correlation between the gob-side entry (GSE) stability and coal pillar width during longwall top-coal caving mining in extra-thick coal seams and found that the GSE with an 8 m coal pillar was destressed and minimal GSE deformation occurs. Fan et al [16] calculated the range of the internal stress field from the perspective of the stress distribution in the surrounding rock, thereby determining the width of coal pillars and validating them onsite
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