| Located in the transition zone between the second and third flight of stairs of China's topography, stretching over both low hilly region of East Sichuan's parallel mountains and valleys and gorge-dominated areas bordering Sichuan and Hubei province, the three gorges reservoir area is characterized by varied geological conditions and is prone to floods and rainstorms, hence one of natural calamity-stricken areas in our country with high frequency. Liujiawan landslip, typical of its kind, situated in Fengjie county which is notorious for frequent occurrences of geological disasters in the Three Gorges Reservoir area, is posing great menace to finished projects constructed for migration, slowing the development of new city area for migration and has a negative impact on society. Hence, there is no time to delay for its comprehensive tackling.Based on the survey of geological conditions triggering landslip and features of the landslide and through varied reconnaissance means, this paper, starting with comprehensive analysis of its geological surroundings, thoroughly discusses how the landslip comes into being, its inducing factors and collapse causes. In view of the fact that analysis of a landslide stability is influenced by varied factors and a single method has certain limitations, the paper attempts to introduce the analogy of engineering geology and limited difference into the stability analysis of landslip, on the basis of analogical analysis of comprehensive engineering geological conditions for landslide stability and combined with methods of limit equilibrium and limited difference, makes further analysis and assessment for the landslide's stability and the distribution characters of strain and stress field under different working conditions and calculates the thrust acting on the landslip on the basis of which a tentative preventative program is put forward.This research leads to such conclusions as below.Liujiawan landslide consists of two parts, the old landslide and the new one in terms of its boundaries, deformation features and formation. The old one is characteristic of large rock slide with no signs of deformation and its volume being 793×104m3, whereas the new one has a sliding volume of 122×104m3,deforms apparently, and its recent deformation is of wriggling slip.The original landslip in Liujiawan results from interaction between stratum rock properties, geological structure, topography and physiognomy, the structure of slope and conditions of weather and hydrology, while the new landslip is induced directly by people's irrational construction engineering around it.The old landslip of Liujiawan is typical of the mode of bend-rip deformation and damage, its rock mass evolving from bend, tensile crack, to rock stratum breakage and crush before slipping. However, the formation of the new landslip consists mainly in the excavation on large scale in front of landslide body and irrationally dumping a great amount of soil on the slope which altered the configuration and structure of the slope, upset its original balance, accelerated the evolvement of the front part of the old landslip body and induced the new sliding with the help of successive rainstorm. Hence the new landslip is featured apparently with inheritance.The results of analysis using finite difference of the stability of landslip and its field of stress and strain show that when it rains the landslide is less stable than when it does not rain, further the old landslip stays still in a stable state, whereas the new one is in a critical state under such condition, that there exists a tensile area near the surface of the sliding body and a shear zone at its foot, and that the movement of the sliding body takes place at the central and front part with its orientation down the slope and hence a high probability of collapse.The analysis using comprehensive analogical technique for engineering geology shows that the old landslip stays stable with its comprehensive stability index being 1.52 ranked as stable, and that the new...
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