STARTING MECHANISM OF DEBRIS FLOW AT MARIDANG GULLY IN JIAWU GOLD MINE IN QINGHAI-TIBETAN PLATEAU

Jiawu gold mine is located in Qinghai Nanshan micro orogenic belt in the east margin of Qaidam Basin, Qinghai-Tibetan Plateau area. The objectives of this work is to ensure the progress of the mineral exploration and mining and to prevent the occurrence effectively of the sudden geological disaster, such as debris flow within the area. A full awareness of the background of the sudden debris flows is established by conducting a detailed investigation of the debris flow, especially the systematically investigation of the Maridang gully river basin, where is the key work area of the mining area. Based on this, we study the starting mechanism of Maridang gully debris flow systematically according to the research achievement of Fei et al.(2004). It was about the starting conditions of debris flow containing fine particles and the meteorological observation data in Tongde county, Qinghai province. The results show that the critical rainfall value of debris flow in Jiawu mining area, Maridang gully, has favorable conditions of the sudden debris flow. The conditions include terrain, source and water power. The debris flows in this area belong to the typical diluted debris flows, or water stone debris flows. They have the following characters: fluid velocity U_W≥5.35m·s^-1 and unit weight γ_c≤1.511t·m^-3.