Eco-geological Environment Survey And Geological Disaster Risk Assessment In Longmenshan Fracture Peng Zhou Zone

China is the most active continental intraplate tectonic activity area in the world, the geological disasters including landslide, collapse and debris flow becomes more frequent.Long-men mountain fault zone is located at the border of the Qinghai-Tibet plateau and the Sichuan basin, controlled by the long-men mountain fault zone of northern Pengzhou City,several villages and towns in the fracture belt. Pengzhou City as 5.12 earthquake disaster extremely serious counties, the secondary geological disasters pose a great threat to Pengzhou City production and living.Take the long-men mountain fault zone of Pengzhou City section as the research object, basis on the ecology geology environment investigation based on the 3 S technology. With scientific and systemic principle, focus principle and comprehensive principle as the instruction, from the three aspects with developing hazards,hazard-formative factors, hazard-affected bodies, building geological disaster risk assessment indicator system, according to the literature material, expert experience, the classification of the ARCGIS geometric spacing and the area actual situation to determine index classification standard, using the analytic hierarchy process(ahp) to determine index weight, with the powerful GIS space model arithmetic analysis ability, calculate the comprehensive assessment scoring value of geologic disaster risk, realize the geological disaster risk distribution. The main research conclusions are as follows:1) The fault fold and the secondary fault fold is very significant in Longmenshan fault zone, pengzhou period, neotectonic activity is relatively strong, crushing rock, surface weathering, susceptible to erosion, scour and formation of geological hazards, such as landslide and debris flow. The rainfall is abundant and concentrated, in addition, the land cover/land use vulnerability caused by long-term man-made destruction causing frequent geological disasters, causing serious damage to residential/area and road traffic facilities,poses a great threat to the people’s life and property safety.2) Long-men mountain fault zone of Pengzhou City about geological disaster types mainly are landslide, collapse, unstable slopes, landslides and so on. Geological disasterpoint totaled 353, including 133 of landslide, 72 of collapse, 92 of potential unstable slope,56 of debris flow, in all types of geological disasters, large disasters accounts for 2.55% of the proportion of the total, medium-sized disasters accounts for 17.00% of the total percentage, small disasters accounts for 80.45% of the total percentage. Mainly distributed in the 650-1000 m, low risk in the middle of the hills and the height of 1000-2000 m,dangerous mountain in the north, the collapse body distribution were positively correlated with structural belt distribution, and a linear distribution along the river valley.3)The long-men mountain fault zone of Pengzhou City about developing hazards sensitivity, hazard-formative factors risk, hazard-affected bodies vulnerability research shows that: in terms of developing hazards sensitivity, fault sensitivity area accounted for80.86% of total area, altitude sensitivity area accounted for more than 55.85%, waviness sensitivity area accounted for more than 55.44%, hydrological conditions area accounted for 64.40%; in terms of hazard-formative factors risk, all area exist in the strong seismic intensity zone, aftershocks risk area accounted for 70.67%, precipitation risk area accounted for 78.50%, historical disaster risk area accounted for 43.11%; in terms of hazard-affected body, the long-men mountain of Pengzhou City about land development and utilization degree is higher, and add the destruction of the 5.12 earthquake, the vulnerability of land cover/land use is high, the fragility of the residential areas accounted for 79.19% of total area, the main road vulnerability accounted for 77.38%.4)Long-men mountain fault zone of Pengzhou City with the comprehensive assessment of geological hazards and the distribution results show that: the high geological disaster risk areas are mainly distributed in northern mountainous region, accounting for16.44% of the total area; moderate risk area are mainly distributed in the northern mountainous and hilly area of central, accounting for 36.24% of the total area; low risk area are mainly distributed in the central low hilly area, accounting for 11.18% of the total area; relatively safe areas are mainly distributed in the eastern plain area, accounting for36.15% of the total area.5) The results of validation and analysis of risk zoning show that the result of risk zoning has very high reliability, tallies with the actual distribution of geological disasters.The research results can provide data support about geological disaster prevention, early prediction and warning of Pengzhou City, provide scientific reference for disaster prevention and mitigation policy for the government, provide a scientific basis for regional reconstruction engineering location and disaster prevention and mitigation engineeringlayout, to prevent and reduce geological disasters to the greatest extent of Pengzhou City people’s production and life.