Study On Evolution Process And Stability Of The No.1 Landslide At The Downstream Of The Jishxia Hydropower Station

The large-scale and complex landslides have been noticed for many years, especially their mechanism, characteristics and stability. A lot of researches had been done, however, to analyze the stability and to predict evolution trend still lack a reasonable and proper theoretical guidance because the characteristics and mechanism of these landslides have not comprehensively and systematically understood. The current studies on landslide mostly concerned about the landslide itself so that the evolution of landslides were either completely separated from or not closely enough contacted with geological environment. The theory of spatio-temporal evolution for study landslides from both temporal evolution and special pattern is desiderated because it is ignored that the synchronous change of special pattern happens when the material and energy of landslides changes with time.In the course of study on the No.1 landslide at the downstream of the Jishxia hydropower station, combined with a large number of relevant domestic and international references, it is found that landslide evolution is not pure and sole process of time, but is a continuous spatio-temporal evolution process when material and energy changes with time and space in the process of landslide's geological environment evolution. Based on landslide is place itself in it's geological environment, from both the time evolution and spatial pattern, the formation mechanism and evolution process of landslides are discussed and knowledge of the spatio-temporal evolution is put forward. The spatio-temporal evolution of landslide is defined as a continuous dynamical process of a landslide system in which materials and energy vary with time and space due to coupled interaction of such factors as lithology, structure, physiognomy, underground water, rainfall, earthquake, erosion of river water, weathering, human activities and the others. It shows transmission of materials will shape a new spatial physiognomy pattern and energy redistribution with time will let landslide to a new balance state.Based on lots of data of field investigation, exploration(bores, adits and coasteans), measurement, lab and field experimentation and monitoring, the No.1 landslide at the downstream of the Jishxia hydropower station was systematically studied in light of the viewpoints and knowledge mentioned as above. Firstly, start with the landslide's engineering geological environment, the formation condition and influence factors of the landslide were analyzed, furthermore, the characteristics of the landslide were introduced and explained, including micro-physiognomy, substance, structure of slip mass and structure of sliding surface. Secondly, according to its obvious zonal and layered characteristics and the geological environments and their evolution feature, using the theory of ESS (earth system science) and the viewpoint of coupled action of factors, the formation mechanism and the dynamical process of the landslide were studied by different ways and means, such as mechanics theory, physical model experimentation, numerical simulation and so on. This landslide developed due to interlayer-shear and buckling of layered rock masses of consequent slope. The spatio-temporal pattern and the evolution mechanism varied with continuous transmission of materials and energy exchange during dynamic evolution of the landslide. Thirdly, on the basis of new understanding of the landslide's characters and evolution mechanism, the physical and mechanics properties of both sliding body and sliding zone were studied through field and laboratory tests. The physical and mechanics parameters were consequently selected. Fourthly, current stability of the landslide was qualitatively and quantitatively researched with such methods as engineering geological analysis, several limit equilibrium methods and displacement monitoring. Then, using these results evaluate the stability of different layers and zones. Finally, based on characters, deformation mechanisms, evolution process, current stability, influence factors and their variation in future, the evolvement trend and movement character were forecasted on the following conditions, atomization-rain of jet overflow, earthquakes and coupled action of many factors.The ESS-based spatio-temporal evolution of landslides emphasized that the formation mechanisms and the dynamical evolution process of landslides must be studied from both spatial and temporal concept and modified the classic knowledge of about landslide evolution, that is, consider landslide as it stands and separately consider time and space. Based on this viewpoint, the characteristics of a landslide can be correctly cognized so as to give a rational guidance to research the physical and mechanical properties and select corresponding parameters, to evaluate current stability state, to predict future evolution trend and to map out relevant treatment measure The research results can be used for reference to study and treat other large-scale and complex landslides.