| The asphalt concrete core dam that has greatly developed in the past 50 years is a new type of dam structure.With the further development and maturity of dam construction technique,the dam height is increasing,the local cracking of core wall often occurs,but now the study on the stability of permeability and dam slope is less.According to the problem of core wall cracking.This paper investigates dam seepage stability of asphalt concrete core when core wall cracked,and also analysis the influence of reservoir water level fluctuation to the stability of upstream slope and downstream slope,at last,research on the seepage in some hydro-power station,the main study content and the corresponding results are as follows:At first,by studying on the effect of core crack relative position,fracture length,slit width,cracking at the same time in different position,different water head height and the change of permeability coefficient of transition material and rockfill body to total seepage flow,I can find that: Slit width of minimum the influence of seepage field,followed by cracks in the relative position,and the greatest influence on seepage field is the fracture length;compared with rockfill body,permeability coefficient of transition material mainly affects the seepage flow in crack;when fracture cracking,the transition material around the fracture all exceeded the maximum allowable gradient,which caused seepage failure;that crack is too long can lead to the outfall seepage hydraulic gradient is greater than drainage edge hydraulic gradient,which also caused seepage failure.Secondly,when core wall local cracking and water level changes,their influences on dam slope stability of asphalt concrete core wall have also been studied,we found that the most sensitive position which influence the stability of dam slope located close to the location of the dam foundation;with the growth of thecrack length,the downstream dam slope stability is reduced,and decrease amplitude is obvious,it is in danger;when the reservoir water level changes,transition material permeability coefficient has little effect on the stability of upstream dam slope,the effect on the stability of the downstream dam slope is bigger,the rockfill body permeability coefficient has a great influence on dam slope stability in upstream,less effect on the downstream dam slope stability;the changing amplitude of reservoir water level in main influence changing range of upstream dam slope stability,less effect on the downstream dam slope stability;the changing speed of reservoir water level mainly influence the changing speed and amplitude of upstream dam slope stability,the lower the reservoir water level is,the faster the velocity is,stability of upstream slope stability decreases quickly and clearly.Finally,a hydro-power station is studied under different operating conditions of the whole three dimensional seepage and optimization scheme research,it shows that dam under different running state has good anti-seepage ability,and can satisfy the demands of dam seepage stability;the seepage of asphalt concrete core wall dam is primarily circle seeping,impervious curtain has a great effect on seepage flow of dam bottom,sand gravel overburden and some strong weathered should be changed and filled in the engineering;core wall local cracking has had a huge impact on the seepage flow of whole dam,small crack can make total seepage flow of the whole dam multiply,measures should be taken to prevent the core wall local cracking in the practical engineering,and also should be strictly put an end to the fracture length too long,ensure the overall anti-seepage performance of asphalt concrete core wall dam and dam seepage stability. |
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