关键词: 主应力差, 转移, 支护

Abstract: In terms of surrounding rock control in large section open-off cut, open-off cut No. 5206 in a mine is selected as study case. The principal stress difference, deformation and fracture field are studied in the process of width from 6 m to 10 m with UDEC. Research results show that: the principal stress differences increase gradually in shallow part and decrease in depth. With the width increasing, the maximal principal stress difference maintains a constant level at first, then decreases gradually in the roof, and decreases at first, then remains constant in the floor, and increases gradually in the rib. The moving range of peak: rib>roof>floor. The curve of displacement in roof decrease exponentially, but has obvious inflection point, which decrease terracedly in the floor. The maximal surface displacement: roof>side walls>floor. The fracture field is divided into three areas: fracture transfixion area, fracture area and microfracture area, which are all distributed as semi-ellipse, the extent of cut through:middle part>two sides and shallow part>deep part. It is believed that high-performance bolt hold the slippage of fracture effectively. The double truss cable can be anchored in the shoulder angle area, which has no fracture, and pre-tension overlays the area. Also, the double truss cable can close the shallow part of roof and reduce principal stress difference. Based on above, a high strength and high pre-tension bolting support scheme of band net and double truss anchor are proposed. The open-off cut achieves self-stabilization after 10 days when it is dug out, the total roof separation is 3 mm, and the roof-to-floor relative convergence is 125 mm, both sides relative convergence is 94 mm.

Key words: principal stress difference, transfer, support