Clay Content Influence The Formation Of Shallow Landslides And Range Transport

5.12" earthquake triggered a large number of landslides, collapses and other geological disasters, which caused loose accumulation body. On the condition of rainfall, the body is easy to form a shallow landslide, resulting in mudslides. Therefore, for the mechanism of shallow landslide and after sliding, which has important scientific meaning, but also has great practical application value on subsequent landslides.Landslide translates into debris flow, which comes down to the mechanism of landslide, is influence to the sphere of landslides. The problem is kinetics of landslide and debris flow formation of intersection, so the research on this issue has importantly meaning of scientific theories, but has great practical application value.The paper focuses on the mechanism of shallow landslide that is initiated by the loose accumulation body after the earthquake through indoor physical experiments on the basis of field reconnaissance. On considering the influence of clay content, it obtains the actuating mode of shallow landslide and sliding scope of shallow landslide through a large number of indoor simulated experiments. The main results are as follows:1) Clay is necessary condition of shallow landslide formation. When the clay content is 0% of the trials, it is easy to form unhindered flow channel of fluid, as little of clay is it strong on the accumulation body of permeability, is poor at the water- holding ability, and is weak at the water retention. At the same time, lacking of clay content between coarse particle makes the deposit of internal friction angle is large, the integrity stability of the deposit is strong, so much as it cannot generate the shallow slide.2) Deposit clay content is too large(15%) and induced debris flow rather than shallow landslides. When the pile body clay content is too large, accumulation in the body between coarse particles and coarse particle pore, most by the viscous grain filling, make deposit themselves less permeable. Test process, the water in from the trailing edge is greater than that of water infiltration rate, deposit and trailing edge to produce water, with the expansion of the water area, under the influence of slope and surface runoff, to form a stable channel. Deposit so high content of clay, and no form of shallow landslide, but the debris flow.3)The formation mechanism of shallow landslide is the static liquefaction process. When the water is permeating, it will take away a lot of clay content, which leads to settlement at the trailing edge of deposit.As the water contains a large number of clay, when the water penetrates to the slope toe, it will be obstructed on the leading edge of deposit drainage channel, which causes the water content of the accumulation constantly increasing and generates the excess pore water pressure, thereby results in the effective stress and stability of the deposit decreasing, ultimately forming shallow landslides.4) There are different boot modes of shallow landslide under different clay content. When the clay content is 0%, the settlement is small at the trailing edge of deposit, at the same time, the drainage channel at the leading edge is incompletely blocked, and the water will outflow under a small amount of clay. Due to front the water flow is less than the trailing edge of infiltration of water,the accumulation body of water content is in a state of increasing,eventually leading to landslides. When the clay content is large, the settlement is relatively great at the trailing edge of deposit, meanwhile a great deal of clay content completely blocked with frontal drainage channel, which makes the water don`t drain.5) The damage degree of shallow landslide is judged by excess pore water pressure. Excess pore water pressure is caused by the mutual extruding soil. The higher the excess pore water pressure, shows that the greater the degree of soil squeezing, the worse stability of accumulation body, the higher the damage degree, when shallow landslide occurs. According to the change of excess pore water pressure at the bottom of the deposit, it can gain the extrusion force at different locations. The leading edge of excess pore water pressure judges for the condition of sliding out according to the extrusion of sliding soil in the process of sliding.6) The shallow landslide has different influence scopes under different clay content. When the C lay in the deposit is slipping, it can reduce the friction between soil and the energy loss, so the more content of clay, sliding distance is farther. Meanwhile, clay also can enhance the capacity of soil cohesion force and cementation, when clay content is large, sliding distance tends to be stable, however the growth of the volume and stacking thickness is linear.