Stability Mechanism and Control Factors on Equipment Removal Area under “Goaf‐Roof‐Coal” Structure

Abstract

One of the main difficulties in longwall mining (LM) is the movement of mining equipment from one panel to the next panel during mining process. The shields of the LM face may be damaged by the collapse of the roof in shallow coal seam under the “Goaf-Roof-Coal” (GRC) structure, especially when moving the shields from the current panel to the next panel. In order to solve this problem, the stability mechanism and its control factors during the LM equipment removal were investigated by using comprehensive methods including theoretical analysis, numerical simulation, and field validation based on the working conditions of Panel 31102 in Liangshuijing Coal Mine. The numerical simulations demonstrate that four different failure zones, shear failure zone, tension failure zone, partly elastic zone, and plastic failure zone, appear around the area due to the position of rock and the arrangements of the supports. The shear failure zone, which is controlled by shield working resistance and roof supporting strength, is the main cause of the failure in the removal area. To minimize the shear failure zone, several measures such as optimizing the end position for LM face, decreasing the width of removal area, and increasing the amount of cable support were taken to ensure the stability of surrounding rock in removal area, which have successfully controlled the damage of roof and equipment in Panel 31102. The field observation confirms that the proposed stability mechanism and control measures are effective under GRC structure.

Study on Stability and Control of Surrounding Rock in the Stopping Space with Fully Mechanized Top Coal Caving under Goaf

“…In view of the complex fault structure and the difficulty of roof management during the late mining period of the working face, Song [13] selected a reasonable position of the stopping line through the study of roof transport law and analysis of mine pressure measurements. Through numerical simulation, Chen et al [14] concluded that there are four different damage zones around the stopping space, namely the shear damage zone, tensile damage zone, partial elasticity zone, and plastic damage zone, and adopted various measures such as optimizing the position of the stopping line, reducing the width of the stopping section, and increasing the number of anchor cables to ensure the stability of the surrounding rock in the stopping space. Wu et al [15] proposed a rapid withdrawal technology for nonpre-driven retraction channels in heavily mechanized top-coal caving faces by studying the law of mine pressure appearing on the working face and the reasonable position of stopping lines for the problem of crushed pre-driven retraction channels.…”

Stability and Control of Retracement Channels in Thin Seam Working Faces with Soft Roof

“…e retracement channel connected with the working face needs to be set in the stopping line for the retracement of working face equipment, which is different from normal mining. e characteristics of large sections, equipment, complex technology, and close proximity to the rear gob determine that only by reasonably setting and supporting the retracement channel, the working face equipment can be safely and quickly retraced [2]. In the working face of a thin coal seam with a soft roof, the soft roof easily causes roof falling (leakage) and support failure in the retracement space because of the low mining height.…”