Study on leakage dissolution around the dam foundation of the Qingju Hydropower Station and its engineering influence on the dam

摘要

Leakage dissolution is one of the potential threats to the long-term operating safety of a dam. The aim of this paper is to analyze the characteristics of leakage dissolution around the dam foundation of Qingju Hydropower Station and evaluate its engineering influence based on laboratory testing and in situ monitoring. Comparative analysis of water samples in 20 representative positions shows that the bedrock of the dam foundation has been enduring obvious dissolution under the effects of the groundwater. In situ monitoring data of displacement and leakage during the period from 2005 to 2013 indicates that there has been no excessive deformation, obvious uneven settlement, or concentration leakage in these nine years, and; therefore, the leakage dissolution of the dam foundation has not resulted in critical danger to the safety of dam so far. However, with an annual amount of gypsum dissolution discharged by the drainpipes of about 1.82 x 10(5) kg, long-term leakage dissolution may be hazardous, besides the higher content of SO42- than normal in the groundwater of the dam foundation caused by leakage dissolution may invoke some crystal corrosion and decrease the durability of the concrete structures. To guarantee the long-term safety of the dam, implementing grouting is proposed to prevent dissolution or slow down the dissolution rate on the basis of real-time monitoring and feedback.