ABSTRACT: According to the characteristic of open-underground combined mining for resident ore body, the stress change mechanism and rock mass displacements law of slope under open-underground combined mining were researched by numerical simulation, and the research results provided scientific basis for subsequent mining and Stability analysis of slope.
1 INTRODUCTION With the development of open-pit mining, mineable resources of shallow surface are declining. Transition from open-pit mining to underground mining is imperative under the situation. In the 1970–1990 years, the total number of mines inWestern countries increased from 1020 to 1200, an increase of 17.6%, while the transition number from open-pit mining to underground mining is from 48 to 98, an increase of 104% . The stability of transferring open pit mining into underground mining is different from the stable side of a single open-pit mining, but also different from the pure underground mining, The open-underground combined mining combined mining experience the two disturbance of mine open pit and underground rock excavation, so the stress field and displacement are more complex . Gushan Iron Mine is the major iron ore base of MaGang Iron & Steel Group, which is designed with open-pit mining method, and it has formed a 150- meter-tall open slope after years of mining. But the stress change mechanism and rock mass displacements law of slope under open-underground combined mining have not been researched.
GEOLOGY AND ENGINEERING SITUATION 2.1 Geology Situation Gushan iron ore deposit is located under XiaYangZi Depression which is in the southern tip Ning Wu fault basin, and in the short axis of ZhongGu anticline, its inner is gabbro-diorite, around are shale and siltstone in the Triassic Department of yellow polo team, Group sandstone of Jurassic, andesite of early Cretaceous Gushan Group, andesitic volcanic breccia and mudstone, shale, siltstone, tuff and so on.