Similarity analysis of time series of reservoir water level and dam foundation uplift pressure

Abstract

Concrete dam safety is relative its foundation uplift pressure reflecting the seepage behavior of the foundation, which was instrumented for monitoring purposes of seepage behavior. Piezometric tube or piezometer is one of the instruments for monitoring seepage pressure and it can be used for long-term seepage condition assessment. The lag effect of Water level upon Piezometric tube monitoring data of seepage pressure is obvious from the time series curve of observation. The lag-effect mirrors many character of dam foundation permeability including grouting and drainage curtain condition. But it is difficulty to analysis quantificationally the lag-effect due to the unsteady seepage characteristics. In this paper, based on standard transform and sub-series, the extremum and region matching method was applied to analyze the similarity of observation time series of reservoir level and uplift pressure. Then by means of comparing the similarity of the observation time series, the lag effect time of reservoir level to uplift pressure was extracted. In the end, grouting and drainage curtain condition was evaluated based on the lag-effect. The engineering case analysis shows that the method is effective and applicable. There is a considerable merit for seepage behavior assessment of the dam foundation.