Construction and First Impounding of the Tokuyama Dam

摘要

Tokuyama dam is one of the largest rockfill dams in Japan,which JWA constructed in Kiso River water system Ibi gawa. The purposes of the dam are flood control,maintenance of normal function of the river,new irrigation,and power generation.Construction works commenced in 2000.JWA started first impounding from September 25,2006,and reservoir water level reached its highest surcharge water level on A-pril 21,2008. The first impounding was completed on May 5,2008 by lowering 10 m of water level (approximately 123,000,000 m3 of capacity). Tokuyama dam is located near the epicenter of the Nobi Earthquake (1891,M 8.0),The stability of the dam was verified according to usual stability calculation and dynamic analysis.In addition,it a-dopts the lower limit value of core width as well as the filter width in the dam of the same scale in Japan.In order to guarantee the safety against seepage failure of the core zone,the core material of over 15 in plasticity index was used,it set "Tokuyama dam filter standard" based on NEF test proposed by Sherard (1985) that regulates D15 of filter material smaller than 1.4mm,and conducted Elastoplastic consolidation analysis at the same time. In first impounding,JWA monitored the seepages,pore pressure,earth pressure,deformation and settlement. Through the measurement,it proveed that no abrupt changes occured in the measured value,and the value of each measurement fits within the range expected before first impounding,Thus the stability of dam body and foundation of the dam was verified. This dissertation is to report the concerned behavior measurement results which accompany pioneering design,and tests applied to the domestic largest dam construction.