Characteristic And Formation Condition Analysis Of Mountain Torrents Geological Hazard Of Yuxi Yunnan Province

The thesis relies on the project - "mountain torrents hazard, preventing and curing and planning project of Yuxi" carry on materials collection and establishment of thesis, getting overall to summarize Yuxi Yannan Province mountain torrents hazard characteristic, type, hazard order. That distributed and formed the terms, and has prevention and cure zoning to study. In this paper, it has been put forward that one comprehensive prevention suggestion about mountain torrents hazard's Yuxi city, and adopted the method to treat to different danger targets with a certain discrimination. Than the propose that should carry on the geological hazard the total programming of mountain torrents to the whole research district. Bring out the characteristic of the debris flow according to the mountain torrents, the situation that prevent and cure the current situation and take precautions against natural calamities. And it is not the integrated control programmer that a project measure combines with project measure to make.River development of stream within the territory of Yuxi, belong to the Red River series and the Pearl River series. The rivers of two major river systems have a typical mountain area river characteristic. The domestic big flood is idiopathic and strong, the forecasts and predicts that it is great to prevent the degree of difficulty. Mountain torrents take place mainly hazard in the low mountain pass hills area, mainly it influence by precipitation flood and the landslide and debris flow geological hazard that bring out that more cause. The mountain torrents hazard of Yuxi possesses the characteristics of the following:1 The scale of debris flow relies mainly on the fact that medium-sized and small-scale in the district. It mainly expects for the development at developing stage of debris flow, with the form type is mainly "V" ditch valley type of style of calligraphy. Loose solid of debris flow supply way of material collapse for ditch bank, and the likely to suffer from degree-high and likely to suffer from zone, distributing of the development space is in the new flat county mainly, secondly it is Yimen county.2 In the district the most landslips are on the wriggled developing stage, having latent threat. Landslip destroy the mode and rely mainly on towed, a few, for passing type or the two compounding type, the landslide body makes up materials, is mainly cushion gravel soil , include the cushion gravel powder soil , including the cushion gravel clay. Landslip bed materialit's the softest stone or sandly shale make up the softest hardest alternate rock stratum in each other layer relatively for the Mesozoic Erathem red layers of sandly shale mainly, secondly is constructed the rock stratum with broken function for the hard floor of groups. Landslide accuse of sliding surface with incomplete to accumulate , slope accumulate layer (pile up layer ) soil body or base rock connect the surface as the main fact, the less aspects in fault and rock stratum. It's thickness layer not shallow for being getting more middle-level mainly. The scale of landslide relies mainly on medium-sized and huge. The time of landslide is distributed the characteristic as 2001- 200 years. While space distribution is county mainly to come down in Xiping, E San and Yuanjiang county secondly.The consequence indicated by research that the forming condition of the geological hazard of mountain torrents of Yuxi is as follows:1. Atmosphere precipitation is immediate reason which causes the mountain torrents hazard ; The topographical geological condition is a basic factor which causes the mountain torrents hazard; The human activity is the important reason that aggravates mountain torrents hazard to take place .2. According to the equivalence line chart of annual precipitation of Yuxi, according to the first zoning it can divide precipitation district in to two different conditions which the value for precipitation is divided in to higher and medium: annual value for precipitation ^00 mm and ^900 mm. In addition.According to the second zoning it also can divide precipitation district in to three different conditions which the max value for rainfall is divided in to higher , medium or lower: the annual heavy rainfall in 24-hour mean value ^70 mm,70 mm ^60 mm and <60 mm.3. in the prevented and cured district to the mountain torrents hazard, according to minimum value for rainfall in a certain period(24h) which is the immediate reason that couse the mountain torrents taking place, it can divide district in to six different conditions where the most likely to be suffer from Mountain torrents hazard,three different conditions where likely and two different conditions where lowest likely .4. According to the topographical slope, it can divide the district in to four differences as follower:I (<10° ): The area is about 3515 sq. km. , accounts for 23% of the whole district area.II ( 10-25° ) : The area is about 9018 sq. km. , accounts for59 % of the whole district areaIII (10-25° ) : The area is about 2293 sq. km. , accounts for 15 % of the whole district areaIV (10-25° ) : The area is about 459 sq. km. , accounts for3 % of thewhole district area5. According to the rock project of the soil nature ,it can divide district in to two different conditions between the area where the most likely and the likely suffer from Mountain torrents hazard. The most likely: debris flow, Landslide, Soft rock, the Softest hardest alternate rock, Soil. The likely: the Softer harder alternate rock6. In the districts where higher , middle and lower likely to suffer from the 3 kinds of hazard, the area percentage that the topographical slope accounts for is very close, almost 10° - 25°. The area percentages are greater than 55%. Between 10°~45°, stream river floods are prior in the district where likely suffer from the hazard; debris flow and landslide are prior in the district where the most likely to suffer from the hazard. According to prones of occurrence it can divide the whole district of Yuxi in to 14 different conditions where the most likely to be suffer from Mountain torrents hazard and 14 different conditions where likely and 12 conditions where lowest likely .