STABILITY ASSESSMENT OF LANDSLIDE GROUP WITHIN FAULT SLIPPING ZONE AT OPEN-PIT IRON MINING STOPE IN DAYE

It examines a landslide group within the Ⅱ District at the East Open-pit Stope of Daye Iron Mine site. It is located in the slipping zone of the fault No. F25. It is a group of high and steep rocky slopes formed by manual mining excavation. The diorite and iron ores in the fault zone were fragmented into typical breccia and smithereens. The development of joints is relatively well. The landslide group is consisted of three main slide bodies, and some cataclastic rocks and soils. Its average length in plane is about 138 m. Its width is about 120m. Its height difference 85 m. Its overall slope angle is 36. Its total volume is about 1.1107 m3. The underlain bedrock is silty mudstone. The landslide body is consisted of silty clay including fragmentary rock blocks. Using analytical method of natural historical analysis and engineering geological analogy, this paper discusses the failure mechanism of the landslides. It is found that the formation and development of the landslide group is a result of the comprehensive effect due to many factors. The factors include the type and property of rock and soil, the structure of rock mass, the tectonics, the topography and the geomorphology, water, as well as other inducing factors. The stability of a typical landslide is analyzed and evaluated comprehensively using limit equilibrium method. For four working conditions are taken into account in the analysis. They are the present situation, the heavy rain, the seismicity and the combined effect of heavy rain and seismicity. It is found that the factors of safety are equal to e 1.256, 0.961, 1.198 and 0.954, respectively. The calculation results show that the rainfall is the main external cause that controls the stability of this landslide. A scheme for prevention and governance is proposed according to the actual situation of this landslide. It includes avoiding the use of the anti-slide pile strengthening and the blasting operation underground, provision of intercepting drains and drainage ditches in posterior wall and surface of landslide body, cement mortar caulking, load reducing and reverse pressing, as well sa slope surface greening. 