Research On The Regular Of Exchange Between Water & Gas And The Stability Of Unsaturated Loess Slope

Loess belonging to the unsaturated soil are mostly low moisture soil, and climate change has a great influence on water content of the soil near the surface. Loess is in unsaturated state, but When it is rainful, the unsaturated loess is very easy to achieve partial saturation. So, the shear strength of soil reduce at a very fast speed and pore-pressure water becomes negative. Then the safety factor of slope decreases, and even lead the loess slope slide. Through the research discovery, we can find that moisture infiltration is a major cause of landslide, but awareness and understanding for the relationship is not enough. In landslide remediation process, if we can determine the moisture distribution and temperature change tendency of the slope scientifically and reasonably, which will greatly save the engineering investment.In this paper, on the basis of theories which is about the unsaturated loess slope, Ma Lan Loess in Lanzhou is a case of study, combined with laboratory based testing and indoor model test, using the combination of qualitative and quantitative analysis. Made a a series of detailed studies on stability of the unsaturated loess slope under the action of water vapor exchange, and made some valuable research results.First of all, it was carried out the indoor physical properties test on selected unsaturated loess, which measure the gradation curve, the optimum moisture content, maximum dry density, liquid and plastic limit index, coefficient of permeability, etc.Secondly, we designed the interior model of unsaturated loess slope, through manual sprayer provides moisture, warm lights provide heat, to make a experimental study on water vapor exchange.To make a joint monitoring of model soil,water displacement device, temperature testing device, testing device are used, which record the moisture, temperature, and displacement. It is aimed at the research of unsaturated loess slope under the condition of water infiltration and sunshine of the rule of temperature field and moisture field, and makes a analysis on the formation mechanism of geological hazard, as theoretical support for the failure mechanism of slope and provides the design basis for construction in progress.Finally, based on the moisture exchange model tests, through the unsaturated seepage software SEEP/W to simulate the high loess slope which is from Lanzhou Jiuzhou ShiXiakou under the condition of different rainfall intensity and rainfall time, calculated the pore pressure water and volumetric water content of different layers of model.Couple stability with seepage of, according to the different changes of rainfall intensity, to investigate the changes of shear strength and pore-water pressure with depth.