Slope Stability Analysis And Comprehensive Treatment In Expansive Soil

In the expansive soil area, whether the roadcut or the roadbank, the distortion of side slope and roadbed is very serious and usual, which seldom happens in other terrene roadbed. Highway subgrade in the expansive soil area, affected by physical weathering and wet expanding and dry pinching effect of atmosphere, the side slope soil block breaks, and the soil body shearing strength weakens, furthermore causing the side slope to slide ,collapse, landslide and the roadbed to sink asymmetrically, frost boil, frost heave and so on distortion disaster phenomenon extrusive,, making the strength and stability of roadbed distracted and making the roadbed lose stabilization, affecting the traffic safety. When our country summaries the railway constructed in the expansive soil area, it is often said that it has to slide when meeting roadcut and has to collapse when meeting bank. The side slope distortion and destruction of expansive soil roadbed has the characteristic of repeatability and long-term latent fatalness.Our country is one of the countries where the expansive soil is distributed most widely and the distribution area is the most large. The expansive soil has been found in about 20 provinces cities and Autonomous regions. The highway constructed in the past is low class in gerenal, and the filling volume or excavated volume is relatively small, so the disaster problems are not too extrusive and don't draw too much attention. However, with the construction of high class highways, many areas meet with the trouble of expansive soil , and various distortion disasters take place in the course of construction of newly constructed highways. The stability of subgrade construction in the expansive soil has been an important research subject to be reckoned with in the present highway engineering geology.On the basis of expansive side slope research outcome, the paper makes a parameter study of the expansive soil side slope stability affected by rainfall intensity, saturation osmotic coefficient, cranny craze depth and rainfall duration, hoping to get the change law of side slope penetration field under the condition of considering or no considering the cranny. By comparing with the two conditions, the paper illustrates the necessity of considering the infection of cranny when analyzing the expansive soil side slope.On the basis of analyzing the geological cause of formation of some highwayexpansive soil collapse and slide side slope, the paper tries to quantify the most primary factors affecting the expansive soil side slope for example cranny and geologic setting and so on and put forward the expansive soil roadcut side slope stability forecasting method based on the gray clustering forecasting theory.Through theoretical analyzing and engineering practice, the paper draws the conclusion that cranny have a bigger effect on the pore space water pressure in the side slope and volume water content distribution. The lower the penetrability is, the more we pay attention to the effect of cranny. It is definitely reliable that taking advantage of gray clustering of forecasting theory to forecast the stability of side slope. It accords with the destructive characteristic of expansive side slope.