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Abstract The Xiaojiaqiao danmed lake in Anxian County，Sichuan Province was considered as one of the most dangerous lakes induced by “5·12” earthquake. The height of damming object was 65～75 m with a volume of 2.5 million m3，and its maximum reservior capacity was about 20 million m3. The new technology LiDAR had been used in the topographic measurement which had provided precise and prompt topographic information for the dammed lake disaster mitigation design and its stability evaluation. Based on the LiDAR and preliminary geological investigation，the structural factor，which was beneficial for the landslide dam stability，was pointed out by comparison of old and new topographic maps of the landslide lake before and after the earthquake. The physico-mechanical index of damming object had been selected by experience and back analysis. According to the seepage computation and stability analysis，the two failure modes which were slide and seepage had been excluded，while the overtopping and scouring on top of the landslide dam may become governing factor leading to a dam breach for dammed lake.
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Received: 12 September 2008
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