Abstract: To achieve a deep understanding of the valley deformation in a high arch dam region, it is essential to conduct a quantitative analysis of the deformation characteristics. This paper describes a multi-function adaptive analysis method for this purpose, based on long-term in-situ monitoring data from the Baihetan high arch dam on the Jinsha River. This method involves preprocessing the data and decomposing them through variational mode decomposition, followed by the selection of its modal signals via fast Fourier transform. It determines the range of peak count values using a prominence factor derived from the quantile method, and performs data fittings with three types of base functions truncated to different numbers of terms. Then, by using an explicit expression formulated for valley deformation, we derive explicit models for its velocity and acceleration. In a case study of the Baihetan Reservoir, typical monitoring data are used to demonstrate the analysis of valley deformation characteristics. The results have verified that our method achieves explicit solutions for the time series of valley deformation and its velocity and acceleration, enhancing the reliability and practical applicability of the analysis results. The findings, grounded with the Baihetan in-situ measurements, have theoretical and practical significance for the development of high arch dams.

Key words: high arch dam, valley deformation, deformation characteristics, VMD, adaptive multi-function method, Baihetan reservoir