Geochemical analysis on educts in the drainage corridor of a big dam over Yangtze River

Abstract

The analysis of educts has become an important aspect for the security evaluation of hydraulic construction. Brown, white-based colloidal educts appeared in the left drainage corridors of the dam over the Yangtze River after its 5-year operation, which did not happen in the initial investigation. In this article, the physics characteristics of the educts were affirmed, and the analysis results of the major and trace elements among educts and the corresponding location of water samples, core samples, indicate that educts are the products from the chemical potential erosion of the dam foundation rock. Brown educts are uncertainties Fe and Mn-based materials, mainly derived from the corrosion of the chlorite and biotite, which may be caused by the changes of the oxidizing condition. White educts mainly with Si and Ca are derived from the corrosion of the calcite, feldspar, and partly invalidation of foundation curtain. Additionally, similarities of the chondrite normalized rare earth element (REE) patterns between educts and bedrock further illustrate homologous, and Ce and Eu anomalies relative to chondrite reflect changes of the water environment condition.

Keywords

educt / water-rock interaction / geochemistry / drainage corridor / REE

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