Abstract
Developing longwall mining under weak geological conditions imposes a substantial challenge with regard to the higher risk of falling roofs. Maintaining the stability of the longwall face in this aforementioned condition is crucial for smooth operation. Investigating roof conditions in longwall requires detailed study of rock behavior in response to a few key influences. This paper presents the outcome of a numerical analysis of roof stability in shallow depth longwall face under weak geological conditions. A series of validated FLAC3D models was developed to examine the roof condition of the longwall face under the influence of shield canopy ratio, shield resistance force, and stress ratio. The results show that these three key factors have a significant impact on longwall roof conditions, which can be used to optimize its stability. Two distinct mechanisms of the roof caving behavior can be observed under the influence of stress ratio. The countermeasures of reducing face-to-tip distance and cutting width are proposed to improve the roof condition of longwall face under weak rock. The outcomes show a substantial improvement in roof conditions after adopting the proposed method.
Highlights
Global energy consumption is projected to increase in the decade [1,2]
In particular, we focus on developing longwall under weak geological conditions by considering several local key issues by means of numerical analysis
Since the properties rock change according to theofdepth of longwall excavation, the properties of rockofchange according to the depth longwall excavation, the resultthe of result of the stability analysis of the longwall face is divided into three different depths
Summary
Global energy consumption is projected to increase in the decade [1,2]. Coal consumption is still considered the main player in the energy sector, it is usually associated with emission problems [3,4]. Others have used numerical simulations to estimate and predict the behavior of surrounding rock in a longwall face, the interaction of roof with powered shield support, stability of the coal pillar, and influence of dynamic pressure in longwall mining with substantial outcomes [10,11,12,13,14,15,16]. A series of numerical models is established to investigate the interaction between shield support and roof strata under weak geological conditions by considering different types of shield resistance force distribution, shield capacity, and stress conditions. Based on the validated numerical models, the interaction between shield support and weak roof strata can be investigated in detail and a countermeasure for controlling face stability is proposed which can be adopted in a relevant longwall mining project or be useful for future research work
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