Study On Bank Collapse Forecast Of The Kari Ravine The Third Accumulation Mass In Qiaoqi Hydropower Station Of Baoxing County

Bank collapse of reservoir is complex geological environment problem, the formation of this phenomenon is the process of the slope substance changed from stability to destruction and the opposition with the reservoir level rising and dropping. The problem has the ability of controlling the safety and the long run operations, especially the regular operations of the highway and railway around the reservoir basin and the resettlements in the reservoir basin.Qiaoqi Hydropower Station is the most important reservoir engineering of the Baoxing river basin, the dam site is located about 1km downstream on the East River to the rural Qiaoqi of Baoxing County. Since early December 2006 having been impounding, lots of deposit bodies of the reservoir basin appear signs of creep deformation, of which Kari ravine the third deposit body having the most severe degree of deformation. Kari ravine the third deposit body is located on the left bank of the Kari ravine, a number of transverse tension fissure has been found in slope in surface survey, the situation would not only lead to the Traffic problem as a result of road subsidence, but also lead to a significant damage to residential buildings on the slope. In the future long-term operation of the reservoir, the effection of reservoir level repeated going up an down will be likely to causing the deposit body collapsing on a large scale, therefore the prediction of the bank collapse of the accumulation mass has great significance.Many factors having been considered in the bank collapse prediction Analysis, the most important factor should be the impact of the reservoir level rising and dropping. This article focuses on the possibility of bank collapse of the Kari ravine the third deposit body, in long-term reservoir operation with the reservoir level changing periodically. The focus of analysis leads to the process of reservoir level declining, under the premise of which the stability of the deposit body occured. In this paper, on the basis of the geological survey in the field, considering the results of previous studies and existing engineering data, the method of engineering analogy has been used to identify the necessary physical and mechanical parameters of rock and soil in order to forecasting the bank collapse. Calculated by the use of Plaxis software phreatic line has been got under reservoir water changing in the law. Considering the various causes of different parts in the deposit body, five profiles have been chosed representatively. Through the analysis of the stabilities of the five profiles, bank collapse forecast of the whole body will be achieved. Using of limit equilibrium method to calculate the stabilities of the five profiles in the conditions of reservoir level declining, continuous rain, earthquake and the state of the earthquake and heavy rain, the Bank Collapse prediction of the whole body will be done. Finally, the software FLAC^3D is used to simulate the analysis of displacement and stress of the five profiles.Potential sliding surface arc-based search results show that the stability of different parts of the accumulation will be reduced to varying degrees; in the condition of continuous rainfall, the slope instability can easily lead to bank collapse. Calculated analysis shows that each part of the accumulation mass is affected to varying degrees in the role of various external conditions, which has the relevant with the body material composition and the material types. In addition, the surge analysis of the accumulation mass has been carried out preliminarily; the conclusion indicates that the instability of the accumulation will not damage the dam because of the long distance between the accumulation and the dam.