GEOLOGICAL FEATURES AND CAUSE ANALYSIS OF QIANJIANGPING LANDSLIDE OF JULY 13, 2003 ON THREE GORGES RESERVOIR

The Qianjiangping landslide is at the left bank of Qinggan river, a tributary of Changjiang River around the Three Gorges Reservoir. It is 44 km away from and above the Three Gorges Dam. At the time of 00:20 on July 13, 2003, a landslide in bedrock occurred at the village called Qianjiangping in Zigui county around the Three Gorges Reservoir. This disaster caused, 15 fatalities, 9 missing, and destroyed four township enterprises. Then the event also aroused wide attention of the public at large. Through the geological investigation in detail after the landslide, this paper gives details on the geological features, precursors as well as the processes of the landslide. According to its substances and structures, the landslide is divided into four zones. They are a) block stone zone, b) base rock fractured zone, c) earth bearing block stone zone and d) boulders and gravels zone from the backscarp to the debris frontier. Furthermore, the paper analyzes physical and mechanical characteristics of slipping zone, and studies the mechanism of the landslide. It concludes that the slope had structures, geomorphology as well as litholgoy prone to landslide. Finally the landslide was induced under the combination of precipitation, irrigation and the impoundment of the Three Gorges Reservoir