Abstract
Gob-side entry is an area where it is difficult to prevent and control the frequent occurrence of rock burst. Based on “Longwall Mining with Split-level Gateways” (LMSG), this paper puts forward the technology of preventing rock burst by a new gob-side entry (NCPG). The abutment pressure distribution of LMSG shows that the stress peak of solid coal is lower than the conventional panel, and the width of the limit equilibrium zone is also reduced by a small percentage. After the narrow coal pillar gob-side entry has been excavated, the peak stress in solid coal increases, and the width of the limit equilibrium zone decreases, so the practical stress concentration increases. However, the NCPG located in areas of lower stress. The peak stress in solid coal of the NCPG does not increase, but the width of the limit equilibrium zone increases, so the practical stress concentration decreases. NCPC makes the concentrated stress transfer into the deep coal body and plays the role of pressure avoidance. Compared with the narrow coal pillar gob-side entry, the NCPG reduces the energy stored in coal and rock masses and increases the energy consumption. It has significantly improved the regionality, initiative, safety, and timeliness of rock burst prevention in deep high-stress coal seam mining.
Highlights
With the large-scale exploitation of coal resources in China, the shallow and central coal resources are less and less
Based on the LMSG, this paper proposes the layout of “Negative Coal Pillar Gob-side Entry (NCPG).”
Roadways of the conventional longwall top coal caving (CLTCC) are generally arranged along the coal seam floor and located at the same level, as shown in Figure 1(a). e LMSG is a method suitable for mining thick coal seams. e difference between it and CLTCC is that the two roadways of the panel are arranged along different levels, one of which is arranged along the floor of the coal seam, and the other is arranged along the roof of the coal seam. ere is a trapezoidal coal body left unmined along the edge of the mined-out area, as shown in Figure 1(b). e trapezoidal coal body is lifted by each hydraulic support up to 3°, and the final lifting angle is 15°
Summary
With the large-scale exploitation of coal resources in China, the shallow and central coal resources are less and less. Erefore, the gob-side entry driving technology with a 3–6 m narrow coal pillar is widely used [20, 21]. Is it still applicable when the mine is under high pressure with the risk of rock burst? E practice of narrow pillar gob-side entry in Huafeng coal mine and Yuejin coal mine in deep mining showed that there were still many times where rock burst occurred in the gob-side entry, which were not ideal for the prevention of rock burst [17, 22]. By analyzing the stress distribution of the surrounding rock of the gob-side entry with narrow and negative coal pillar, the respective rock burst risk is discussed. The Huafeng coal mine has adopted three layout methods of wide coal pillar, small coal pillar, and negative coal pillar for practical verification
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