震区都汶公路沿线典型泥石流沟淤埋强度评估

Assessment of Sediment Magnitude of Typical Debris Flow Gullies along Dujiangyan- Wenchuan Highway in Earthquake Area

以都汶公路映秀-草坡段为研究区,选择了公路沿线15条典型泥石流沟进行了野外考察、遥感监测、试验研究和计算分析,采用部分泥石流参数计算经验公式并结合大比例尺数字地面模型和高精度遥感数据,初步建立了泥石流淤埋厚度、淤埋宽度和淤埋强度评估模型,进行了泥石流淤埋强度评估分析,并应用于都汶公路恢复重建和防灾减灾。结果表明:研究区段极高、高、中等和一般淤埋强度的泥石流沟分别为8条、1条、5条、1条,各占总数的53.3%、6.7%、33.3%和6.7%,总体呈强烈淤积趋势;8条泥石流的淤埋厚度可能达6~20 m、淤埋宽度可能达111~421 m,具有极高侵蚀产沙和冲淤能力,对流域内及沟口重大工程危害严重;对比分析红椿沟泥石流淤埋厚度与宽度的计算值与实测值可知所建立的评估模型具有较高精度和一定的实用性;评估模型中一些参数来源于经验公式,需要在进一步加强泥石流野外监测和试验研究的基础上,通过实测或试验分析获取,并修正相关经验公式,以满足震后泥石流评估工作需要。

The zone from Yingxiu to Caopo along Dujiangyan -Wenchuan highway is taken as a case study area and 15 typical debris flow gullies are selected. On the basis of field investigation, remote sensing surveying, experimental study and computational analysis, some empirical formulas of debris flow parameters, large-scale digital terrain model and remote sensing images with high resolution are adopted to establish the models for calculating thickness, width and magnitude of debris flow sedimentation, the assessment of debris flow sedimentation magnitude is made. The corresponding results are applied to the reconstruction and disaster mitigation of Dujia^agyan-Wenchuan highway. The findings show that （ 1 ） all the debris flow gullies have a whole trend of serious sediment, and the number of debris flow gullies with the most serious, serious, moderate and low sediment magnitude is 8, 1,5 and 1 respectively, accounting for 53.3% , 6.7%, 33.3% and 6. 7% of the total number; （2） the sediment thickness of 8 debris flow gullies amounts to 6 -20 m and relative sediment width amounts to 111 -421 m, which have a very violent capacity of erosion and sediment, and has caused great harm to the major projects in the watersheds and outlets of debris flow gullies; （3） the established assessment models are feasible and have a higher precision according to the contrast of the calculated values with the measured values of sediment thickness and width of Hongehungou debris flow ; （4） some parameters of the assessment models are adopted from empirical formula and the related empirical formula need also to be improved through measured or experimental parameters so as to meet the needs of the risk assessment of post-earthquake debris flows.