| With the "Western Development" strategy continuing to deepen, loess area is widely development and utilization gradually, as a weak negative effect of the loess area, loess landslide hazard grow day by day, and seriously hamper the development. Loess landslide research has received increasing attention, but the disaster mechanism remains a major international problem, in-depth study has important theoretical significance, economic significance and social significance.Select freezing-thawing period of loess landslide as the research object, use geography, mathematics, mechanics and systems science-related theories, use systematic investigation, extensive information on induction, numerical simulation, 1m ground temperature test, fuzzy analysis, hierarchical analysis methods, do beneficial aspects to loess landslide mechanism of freezing-thawing period, finding the development rule of groundwater and time prediction of loess landside. The main conclusions are as follows:(1) Introduction of Japanese decline and groundwater experts, Dr Atsushi Takeuchi proposed "1m geothermal theory", using the theory can establish "1m ground temperature distribution" and "Location of underground water veins," and further analysis of horizontal distribution of groundwater decline, study the location and size of underground water veins.(2)ADINA-T simulation results:When the outside temperature is 0℃, the temperature gradient gradually increased from the slope surface to the base, but to a certain depth, the temperature has remained unchanged. when the freezing time is 1 month, the outside temperature is -10℃, the freezing depth is about 0.95m. When the freezing time is the 2 months, the outside temperature is -15℃, the freezing depth is about 1.15m.When the freezing time is about 3 months, the outside temperature is -20℃, the freezing depth is about 1.35m, arrive maximum depth. The maximum depth of theoretical derivation is anastomosised for the measured.(3) Establishing of "a groundwater transporting model of landslide before and after the freezing", using the loess landslide types of loess-mudstone planar landslide which is widest distribution as landslide model, using principles of hydrology on the base of determining the conditions and boundary conditions assumed, derived the basic differential equation saturation line; and analysis of frozen ground water seepage line distribution.(4) The feature of " effect of promoting slip by frozen perched water" are as follows: Hamper the runoff infiltration, but also blocked the groundwater discharge channels, the slope become as a "storage bladders," expanding the scope of the distribution of groundwater, rising the water level, increasing dynamic and hydrostatic pressure of landslide area, reducing the slope in particular the strength of rock and soil mass, speed up the slope deformation and even induced landslide hazard.Take Saleshan landside as an example,analyze the causes of the landside,thought that the freezing-thawing affect is the mian contributing factors and triggers;Take the Huining County Taiping landside as an example,the calculation of the stability of freezing before and after,the results show that the role of freezing-thawing is greater to the stability.(5) Using "Improving the extension of AHP," take into account both the human right to determine the fuzzy character of things, but also to avoid the traditional analytic hierarchy process a large number of spreadsheet work. Established a "slippery slope time prediction of extension AHP model", the use of improved extension of AHP, the macro can be signs of landslide investigation had determined that landslide developmental stages.In this paper, the results can be better explained the frequent loess landslide phenomenon of freezing and thawing period, enrich the time of landslide prediction theory, help determine the distribution of loess area of groundwater, have a certain reference to loess landslide prevention programs and decision-making.
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