Analysis On Seepage Field And Study On Impervious Curtain In QingJing GaoBaZhou Hydropower Station

Taking QingJiang GaoBaZhou hydropower station as the study subject in the paper, how to study and solve the problem of leakage by-pass dam are demonstrated in the karst area with intensely developped karst and complicated engineering geology conditions.The main contents of the paper contain four parts.Studying on engineering geology conditions of the dam site is the main content of the first part. Engineering geology conditions and geologic structures are systemic studied, containing topographty and physiognomy, rock characteristic of stratum, geological structure, rock weathering characteristic and so on. The karst developped rule and feature are investigated in detail in the area of dam site. Subsequently controlling factor of developped karst in the area is explored. At the same time karst developped rules, i.e. karse mainly controlled by fault, strking NE (along the river), and secondly by rock lay and drainage datum plane (QingJiang), are revealed. Based on using boring data and analyzing karst developped lower limit of areas bearing different rock characteristics, geologic basic data for setting impervious curtain are offered.Studying on geology of the seepage is the main content of the second part.On the basis of investigating groundwater dynamic feature and groundwater distribution feature, the distribution rule of seepage field is ascertained and leakage by-pass dam field is confirmed. Based on reaserching on water lever field and geochemistry of groundwater, a litter transverse watershed is detected and its elevation is acquired in the right bank. According to the fact above, the quantities of leakage by-pass dam are calculated and forecasted in the condition of normal water storage without impervious curtain, offering dependable geology fact for setting impervious curtain.Studying on three-dimensional seepage field is the main content of the third part. Three-dimensional seepage calculating model uses three-dimensional seepage basic differential equation, and using Bathe conduction matrix method deals with free surface of seepage. Simulating and analyzing are applied in four conditions, natural condition,normal water storgage condition, normal water storgage without impervious curtain condition and normal water storgage with groundwater recharge condition. By analyzing the permeability parameter sensitivity, the main factor effecting leakage by-pass dam is detected. Whereafter comparing with geologic macroscopical judgement and result of analytical solution, the sheme preventing leakage can be confirmed purposefully.Studying on scheme preventing dam leakage and project inspection are the main contents of the fourth part. In the light of researching on seepage field and seepage field by-pass dam, the optimal measure preventing leakage is obtained. According to main factor effecting leakage by-pass dam, corresponding sheme preventing leakage is ascertained, namely, preventing leakage mode natural curtain and manual curtain processing together. Project running inspection proves that preventing leakage effect is all right.