Reach On The Loess Landslide Triggered By Engineering Loading

The loess distribution area in China was about 63,000 km2, which account for 6.6% of China’s land area. The wide distribution, great thickness, typical structure, and continue deposition of loess make loess plateau a loess natural museum, as well as frontier highland of loess research in the world. It is tough to achieve the urbanization construction goal proposed in the 18 th Party Congress in the loess plateau, for the major disasters developed in the loess. For example, as the provincial capital city, Lanzhou was almost surrounded by the loess landslide, collapse, debris flow and other geologic hazards, which seriously threatened the safety of the city and greatly restricted the development of it. Besides, as the mecca of Chinese revolution, Yan’an was located on the long and narrow slope zone. About 80 large loess landslides and collapse developed here had already limited the development of Yan’an city. In order to build the new cities, Lanzhou and Yan’an are forced to cut slope and fill the ditch in the county. Hence, it is difficult to avoid the loess landslide disaster issues triggered by engineering loading.Based on the loading induced loess landslide-formative, causing factors as well as the evolution mechanism, this paper carried on the systematic researches on the distribution rules, formative mode, formation mechanism, evolutionary process, and technical methods.The main conclusions are as follow.(1) The main loading types that can trigger the loess landslide are planar loading and dot loading. And the planar loading can be divided into strip uniform distributed, rectangular uniform distributed, square uniformly distributed and triangle planar loading types.(2) After loading, the vertical stress has a large influence depth, while the influence depth of the horizontal stress is 2 times. The max shearing stress induced by loading appeared on the edge of the loading zone, and this is also the main reason for the the shearing fracture developed there.(3) There are two slip bands developed within the loess landslide induced by loading. One is the shallow slip band, which is formed by the connection between tensile fractures developed outside the loading area and shearing fractures, and the other one is deep slip band, formed by the connection between tensile fractures developed inside of the loading area and shearing fractures. The shallow sliding zone usually cuts out at the central of the slope while the deep one cuts out near the toe of the slope.(4) Combined with physical modeling test, centrifugal model test, numerical simulation calculation, and slope additional stress comprehensive analysis, it was found that the plastic zone was developed at the bottom of the tensile area as well as the slope toe, and extended to the middle of the slope. The deformation partition of a loess landslide trigger by loading can be divided into sliding zone, sliding influence zone and nor-influence zone.(5) There are three kinds of deformation failure modes triggered by engineering loading, such as reactivation of old landslides, creep deformation of saturated soil layer, and slope deformation failure in landfill area.The shape and forming process of the loess landslide triggered by loading is closely related with the loading value, loading location as well as the slope gradient.