Causes Of Abnormal Seepage In Xiaojiashan Reservoir Dam

Earth-rock dams are widely adopted dam types at home and abroad.But the seepage problem faced by the earth-rock dam is very prominent,which is the main reason for the safety problem of the earth-rock dam.This article takes the Xiaojiashan Reservoir of Hunan as a project background for a long time since the completion of the project to carry out related research.The specific research contents and main results are as follows:(1)Preliminary analysis of the causes of abnormal leakage.Analyze the abnormal leakage phenomenon in the dam body of Xiaojiashan Reservoir,combined with the construction history and the historical records of danger elimination and reinforcement,and speculate on various possible causes.(2)The cause of abnormal leakage is identified by the dam body material and water leakage.By collecting samples of reservoir water and leakage water on site,conducting component detection and analyzing the difference between pH value and calcium ion concentration,it shows that the underground runoff is relatively smooth and the internal seepage velocity of the soil in the dam leakage zone is fast;,Internal and lower soil samples,the test obtained water content,leakage coefficient and shear strength,etc.The results show that the soil moisture content and leakage coefficient of the leakage zone are higher than other parts,the soil performance is poor,speculate the leakage zone Damming materials for frostbite then form a leakage channel.(3)Evaluation of dam seepage characteristics based on numerical analysis of seepage.Through the design,construction and monitoring data of hydraulic structures,in the ANSYS finite element software,a three-dimensional visual calculation model of the main dam of Xiaojiashan Reservoir was established.The seepage calculations were conducted under different working conditions before and after the dam body was removed and reinforced,the change rules of seepage slope and free surface were analyzed,the leakage amount of the dam body was obtained,the weaker part of the seepage control effect was determined,and the dam seepage stability was evaluated.(4)Clarify dam high water level operation risk and reinforcement operation strategy.The conditional probability method is used to calculate the risk.Under the current flood diversion calculation principle,the high water level risk and the flood risk are solved based on the R-F method.Aiming at the problem of abnormal leakage,the corresponding reinforcement strategy and operation plan are proposed.For earth-rock dams with abnormal seepage problems,in addition to detecting pH and calcium ion concentration,other components in the seepage water can be discussed as the basis for discrimination.It is worthy of further discussion on how to carry out economical and effective measures to eliminate danger and reinforce such earth-rock dams with loosely filled interlayers.