[关键词]
[摘要]
里拉沟在2011年6月6日发生大规模泥石流,给当地村民的生命财产造成很大损失。通过对泥石流物源与地形条件的现场调查,以及里拉沟降雨值的插值计算,分析了该地泥石流的形成机理,认为:1号支沟两岸坡度较陡,沟道纵比降大,沟道内堆积的固体物源在较小的降雨条件下就会被冲走,不利于残坡积物的堆积,所以不具备滑坡产生的条件;2号、3号支沟两侧坡度总体较为平缓,残坡积层较厚,易发生浅层滑坡型泥石流,特别是两岸坡度在20°~40°时最易于发生浅层滑坡,最终分析得出在相同地质地貌与降雨条件下,里拉沟各支沟道发生浅层滑坡的判定方法。
[Key word]
[Abstract]
Lila gully is a low-frequency debris flow gully. On June 6, 2011, most of the northern area of Wangmo County in Guizhou Province had the biggest rainfall in a century, which led to a large scale group of debris flow. The occurrence of massive mudslides caused great loss of life and property. Local transportation, communications, and other infrastructure have been damaged seriously. Based on the in-situ investigations of the material sources of debris flow and topographic conditions and interpolation of rainfall in Lila Gully, the formation mechanism of debris flow was analyzed. It suggested that the 1# tributary has steep slopes on both sides and large longitudinal gradient, which is not suitable for the accumulation of residual deposits as the deposits in the gully can be washed away easily under light rain conditions. Therefore, 1# tributary did not have the landslide conditions. Meanwhile, it found that 2# and 3# tributaries have gentle slopes on both sides and thick layer of residual deposits, which can lead to the occurrence of shallow landslide-induced debris flow, especially when the slope of both sides is about 20 to 40°. Consequently, the criteria for the occurrence of shallow debris flow in each tributary of Lila Gully under the same geological, topographic, and rainfall conditions were obtained.
[中图分类号]
[基金项目]
贵州省地质灾害监测预警与决策支持平台研究子项目贵州省泥石流启动机理及预警预报研究(基金号ZG0064)