| Xinping County, located in the central south-west of Yunnan Province, is one of the areasthat landslides, mudslides and other geological disasters are most serious because of thecomplex geological and geographical conditions, and the spatial and temporal differences inclimatic conditions. In recent years, landslide stability problems are more and more critical,which resulted in significant harm to human society. The formation mechanism, affectingfactors, the stability analysis and prediction research of landslides has been the focus ofattention of domestic and international engineering and academia.Nanen hope primary school landslide is located in Xinping County of Yunnan. In August14,2002, a rainfall-induced deformation adjustment occurred along the base cover interfaceand caused tensile fractures of the buildings on the slope, which posed a direct threat to Nanenprimary school and village. Therefore, it is very significant that to study the stability of thelandslide for disaster prevention and mitigation.Based on clarifying the regional geological environment conditions of the landslide, thispaper gives a detailed analysis of the basic characteristics, the formation mechanism andinfluencing factors of the landslide, and then the stability of the landslide is analyzed andcalculated with the limit equilibrium method and the numerical simulation method. The mainresearching content is as follows:(1)Due to the role of long-term geological forces such as natural gravity, weathering,erosion and other, overlying rock is weathered into thick loose accumulation layer covering thebedrock below, Forming the soft hard geological body of slope. The slope is very steep.Underthe influence of heavy rainfall, the water flows from the crack infiltration to the soil and rockcontact surface, and a weak surface is formed. The water flows through the weak surface,which eventually lead to the occurrence of landslide. Rainfall is the main predisposing factor.(2) The stability of the landslide is analyzed and calculated using the limit equilibriummethod with three typical profile of the landslide under three conditions: in the natural state, thewater level in more than one-third of the sliding surface, the water line more than two-thirds ofthe sliding surface. In natural conditions, the overall stability of landslide is well; in the waterlevel more than one-third of the sliding surface condition, the overall stability coefficient of thelandslide is significantly lower natural conditions; in the water line more than two-thirds of thesurface condition, the overall stability coefficient of the landslide is lowest. The calculatedresults show that the slope stability without considering the stability coefficient is the highest, and with the rise of water level, the slope stability coefficient decreases.(3) Numerical simulation analysis of the main slip surface is completed by FLAC softwareunder three conditions. The result shows that under natural condition the slope is stable; in thewater line located more than one-third of the sliding surface condition, the whole landslide isin an unstable state, and the leading edge of the slope is potential danger zone, that is theleading edge zone is most likely to the instability strip; in the water line located two-thirdsabove the sliding surface condition, the landslide is in Instability status, and the landslide issliding along the bedrock surface as a whole. Slope stability decreases with increasing of thegroundwater level.(4) The result by numerical simulation analysis and the result by limit equilibrium methodcalculation about II-II′in the three conditions are nearly the same. |
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