Study On The Stability Of The Large Accumulation Located In The Upstream Leftbank Of The Luola Hydropower Dam In The Nujiang River

Accumulation is a concept according to formation and physicomechanical properties, refers to quaternary system accumulation effect, belongs to slope deformation and damage the product of continue to exercise stage. Research area is located in the eastern edge of the Tibetan plateau, with the uplift of qinghai-tibet plateau,form this region of landscape high valley. At the same time, river's strong cutting function and violent tectonic movement of this region, cause rivers slope deformation, form a lot of accumulation slope. This kind of slope always be in critical state, to bring the security hidden danger of engineering construction. Therefore, study on the stability of the slope are of important theoretical significance.Luola hydropower station locate on the upstream of the Nujiang river in Tibet ZuoGong county, is the backbone belongs to the Nujiang river upstream hydropower planning cascade development, its upstream link to Lalong hydropower stations, its downstream after Angqu hydropower stations. Luola accumulation locate in the left bank of the river upstream of 2km, has a large collapse accumulation body.Luola accumulation structure is loose, in the case of impound, the stability of the accumulation decreased,and this will threaten the safety of the proposed Luola dam, affecting the normal operation of the hydropower station.This thesis use this accumulation slope as the research object, combining previous part of the research results, get a deep research on the engineering geological conditions of this area and the basic characteristics of this slope, and then, distinguish different partitions according to the composition of the slope upstream and downstream. Because the majority of the surface deformation damage signs buried by loose debris, so, through the surrounding rock mass destruction signs(rock mass structure surface development characteristics of rear edge and downstream edge), find the formation mechanism of Luola accumulation slope.This thesis use the limit equilibrium method for calculating the stability of the slope. Calculate the stability of slope in different areas separately. Calculation conditions consider natural, rainstorm, impound, impound+rainstorm and impound+rainstorm+earthquake, calculation results analysis the influence degree of the impound and rainfall on stability.This thesis use the method of 3D-FLAC to the numerical simulation, calculate stress-strain field characteristics before and after the impound, get calculation results in different areas. Through the change of stress field before and after the impound, find out the stability changes in different areas of accumulation; through the strain field characteristics after the impound, find the most prone to deformation damage position, deformation, slippery surface distribution in the accumulation slope.Accumulation slope has the characteristics of big volume,big divide and steep, calculated the most high waves in different locations formed by surges after the slope destruction,evaluate the damage degree to the Luola hydropower station, ensure the safe operation of the Luola hydropower station.This thesis systemsly analysed the the stability of the Luola accumulation,the research results will help to improve constrction quality control of the roll station contuction, and has major practical singnificance to protect the safety of the roller dam, while of great theoretical significance. And has some reference value for the analysis of the accumulation stability which will meet in the cascade power station construction on the Nujiang River upsteam.