FORMING MECHANISM AND MOTION CHARACTERISTICS OF THE "3·8"JIANGLIU LOESS LANDSLIDE IN JINGYANG COUNTY OF SHANXI PROVINCE

In the morning of 9 March 2016, a landslide-mudflow occurred in South Jiangyang Platform near Jiangliu Village. After that we conducted a field investigation. It is found that the groundwater level had reached the foot of slope, and there were many water spray places. Shallow cracks were widely distributed in the surface, and deep cracks were also visible. It is obvious that the cracks provided advantage paths and promoted the infiltration of water. By testing the water content of the soil in the sliding area, it is found that the hydraulic conductivity of paleosol was very low, and it resulted in the formation of the aquifer in the paleosol. It is estimated that the loess layer collected water and formed a zone with a high water content, and then resulted in the "3.8" Jiangliu loess landslide. Utilizing LS_RAPID, the motion of the landslide was simulated. It showed that the whole motion process can be divided into four stages: 0-4.0 s, which was the first stage of the landslide. The slope collapsed rapidly and the maximum speed reached 10.3 m·s^-1; 4.0-4.9 s, which was the collision stage between the sliding mass with the ground. Then, the speed slowed down, and reduced to 7.3 m·s^-1 at 4.9 s; 4.9-6.7 s, which was called the second acceleration stage. The landslide formed a landslide-mudflow on the flat terraces, and the maximum speed reached 18.4 m·s^-1; 6.7-29.5 s, which was the deceleration stage, and the kinetic energy of the landslide gradually exhausted and landslide stopped. The final sliding distance of the landslide reached 275 m and the time of motion was 29.5 s. The sliding distance and the accumulation range were consistent with the field situation.