Debris Flow Characteristics Of Earthquake Zone

Debris flow in mountain is one of natural disasters, which outbreaks of a sudden, devastating large. Construction debris flow activity near the fault zone is particularly strong. 12 May 2008 Wenchuan County in Sichuan Province, the magnitude 8.0 earthquake, gave birth to numerous landslides, avalanches and potential adverse geological unstable slopes, debris flow for the earthquake area and provide favorable breeding conditions. September 24, 2008, July 17, 2009, 2010 August 12 to 14 worked in Beichuan, Sichuan Province, County, Qing Ping, Longchi, Yingxiu large outbreak of debris flows and other places, causing heavy losses, serious threatening disaster restoration and reconstruction work. Thus, on the earthquake zone of debris flow activity characteristics, disaster prevention and mitigation work on guidance for good.In this paper, debris in Anxian County District 11 as the research background, combined with field survey and remote sensing image analysis of the seismic effect of the spatial distribution of debris flow source, the correlation with the lithology, and topographic conditions of earthquakes on the impact of debris flow. Study found that "5.12" Wenchuan earthquake zone provides a rich debris flow source. The distribution of source lithology is not only effected by the regional, with elevation changes with some regularity, mainly between 1000 ~ 1800m in elevation. Strong earthquake affected areas of the debris flow terrain conditions. A powerful earthquake destroyed the vegetation and surface debris basin soil, many bedrock outcrops, has changed conditions and the water catchment basin runoff conditions. Collapse caused by earthquakes, landslides and other disasters, or accumulated at the foot of the slope channel, changing the channel flow conditions, causing local congestion. Compared with the earthquake before in the same rainfall conditions, the current outbreak of more debris. In addition, the paper by a seismic source of debris impact conditions and terrain conditions, the results, select the drainage area, channel blocking factor, vegetation coverage, lithology factor and debris flow source area and the ratio of drainage area and other five factors, the debris flow activity is divided into five low-level, representing the frequency of debris flow activity 5, the use of fuzzy comprehensive evaluation method in the study area before and after the earthquake debris flow activity were compared. Evaluation factor by the weight allocation, source and drainage area of debris flow activity most. Study found that debris flow activity before the earthquake evaluation results agree well with the actual survey results, reflecting the reliability of the evaluation model; earthquake debris flow activity was significantly enhanced to determine the earthquake area will significantly increase the frequency of debris flow activity. Accordingly comparative analysis of debris flow activity before and after the earthquake, found that in addition Meizi Tang ditch, Maliu ditch, Shiziyuan ditch and other activities of persimmon garden after the earthquake is still mild, the other eight have become extremely active channel, which can be determined Earthquake debris flow significantly increased after the earthquake, outbreak frequency will increase, most of them more than 5 years will be an outbreak of a debris flow. The article also selected two typical debris flow, analyzes the formation of debris flow conditions, development trends are predicted, the study area can be a good representative of the activities of debris flow characteristics.