Slope safety control during mining below a landslide

1 Introduction After over 40 years’ mining the East Open Pits of Daye Iron Mine were formally closed in the year 20001]. There still remains around 12 million tons of ore beyond the pit limit, which would be mined by underground ways. During the transition period, hanging-wall ores were planned to be mined to maintain the balance of mineral supply, to make full use of open-pit facilities and to avoid unemployment of miners. The four selected mining spots are characterized by high and stee…

Slope safety control during mining below a landslide

The East Open Pits of Daye Iron Mine were closed in year 2000 and the ore beyond the pit limit was planned to be mined by underground ways. In order to facilitate the smooth transition to underground mining, hanging-wall ores in the old pits were scheduled to be mined. Xiangbishan pit is one of the four mining spots selected. In 1979 when the pit was mined to around 36 m a.s.l., a landside of around 70000 m3 occurred in its North Slope, leading to the closure of the pit. The pit was then backfilled to 60 m a.s.l.to maintain the slope stability. The hanging-wall ore to be mined is just located below the old slide, so whether the slide will be reactivated and how to control its deformation and stability are the key issues concerned. Based on geological investigation and numerical analysis, it was predicted that the slide would be reactivated and a control measure using the intact ore body as a retaining wall was thus suggested. During mining, displacements were monitored to assure safety. By July, 2003, 383000 tons of ore were successfully mined. Though the observed displacement reached 8795 mm, no major failure happened.The final slope is 110 m high with an angle of 70°.