| In this paper, " Longnan County geological disaster investigation and escaping relocation hidden spots verification " projects as the basis. After completing the field investigation, data collection and analysis, author does systematic analysis on distribution, type, size, developmental characteristics, formation factors of geological disaster hidden spots, so has more comprehensive understanding to the development characteristics of the county. On this basis, author takes the approach of field engineering geology qualitative analysis combined with indoor composite score (semi-quantitative) to evaluate their stability and ease of onset. In order to better guide the work of disaster prevention and mitigation, various types of geological disasters which are more seriously impact on people’s lives and property are specially selected to analyze. Results of this paper are mainly as follows:(1) The main types of geological disasters in Longnan County is landslide, mudslide, ground subsidence, landslide is the largest number and the most widely distributed in all kinds of geological disasters. Scale of landslides are dominated by small-scale landslides, mostly shallow landslides,sliding body substance is mainly residual soil and gravel soil; The main type of mudslides is valley; Two kinds of ground subsidence are mined and karst collapse.(2) On the terrain, geological disasters of Longnan County are mainly distributed in eroded structure low mountains; In the geographical, geological disasters are focus on human engineering activities strong lots and linearly distributed along the road.(3) Domestic geological disasters have sudden, diversity, mass and temporal periodicity features, are mainly controlled by factors, such as topography, geological structure, the nature of rock and soil, rainfall and human engineering economic activities etc. This paper takes the approach of field engineering geology qualitative analysis combined with composite score (semi-quantitative) to evaluate the stability of 207 Survey points of geological disasters in Longnan Country, among them,15 points are good stability,158 points are worse stability,34 points are worst stability.(4) Author evaluate quantitatively Wudang Town Daba Village Gaopai landslide with the transfer coefficient method and numerical simulation method, two results are shown: landslide is steady in the natural state, is unstable in the rainfall condition, this indicates that rainfall have great impact on the stability of landslide. Then, formation mechanism of Huangsha Xinling mining subsidence and Nanheng iron ore karst subsidence are described in detail, the former is induced by the underground mined and water inrush of the old hole induce factor of the latter is that karst groundwater of pit is largely pumped, the upper soil layers produce sinking and cracks. |
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