Abstract
In traditional sequential single-wing mining practices, one-entry longwall mining systems make it challenging to efficiently and smoothly transfer mining equipment during a continuous mining sequence. In two-entry longwall systems, the headgate of the current panel and the tailgate of the next panel are excavated parallel to one another, effectively creating space for the transfer of mining equipment. The tailgate of the panel, however, is subjected to high-mining-induced stresses, causing severe floor heave, which seriously affects the efficiency of coal production. In this paper, field measurements and numerical simulation methods are used to reveal the mechanism of floor heave induced by the rupture and instability of a competent roof. The results show that the positional relationship between the adjacent tailgate and the longwall face is divided into three stages. Throughout the three stages, the area in which the coal pillar is not horizontally displaced moves from the center of the pillar to the goaf, and the area of peak vertical stress within the coal pillar shifts from the center of the pillar to the side nearest to the tailgate. Field studies suggest that the proposed technologies can effectively control floor heave in the tailgates of two-entry longwall mining systems.
Highlights
In one-entry longwall mining systems (see Figure 1(a)), the tailgate of the longwall panel is generally excavated after the current panel has been mined out and the strata above the goaf have stabilized [1,2,3]. is causes significant interruptions and prevents continuous mining
In two-entry longwall systems (see Figure 1(b)), the tailgate of the panel is excavated in advance, permitting continuous mining and solving challenges associated with transportation, ventilation, and gas control
Considering the lateral fracture feature of the main roof above the goaf, Zhang [19] stated that the “three-hinge” structure of the main roof is subjected to extensive horizontal stresses during the fully mechanized mining process of the longwall face, causing severe disturbance in the coal pillar
Summary
In one-entry longwall mining systems (see Figure 1(a)), the tailgate of the longwall panel is generally excavated after the current panel has been mined out and the strata above the goaf have stabilized [1,2,3]. is causes significant interruptions and prevents continuous mining. Within a certain range behind the goaf of the longwall face, the roadway is subjected to high mining-induced stresses caused by the fracture, turning, and slipping of the main roof, resulting in severe floor heave in the tailgate of the panel (stages B and C) [5]. Considering the lateral fracture feature of the main roof above the goaf, Zhang [19] stated that the “three-hinge” structure of the main roof is subjected to extensive horizontal stresses during the fully mechanized mining process of the longwall face, causing severe disturbance in the coal pillar. E horizontal displacement and internal stress distribution characteristics within the coal pillar between the tailgate and the longwall face, the variation of the principal stress angle, and the floor heave mechanisms were evaluated based on field observations and numerical result. Supporting methods and parameters were proposed for controlling the floor heave in the tailgate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
