Dynamic Failure Tests and Analysis of a Model Concrete Dam

摘要

A 1:60-scale model of the highest nonoverflow monolith of Koyna Dam was constructed on a foundation block and subjected to an impact force which produced cracking in the upper portions of the dam. The foundation block was connected to a massive concrete reaction structure by Belleville springs. The impact force was provided by a 1,000 lb wrecking ball mass moving as a pendulum. Instrumentation consisted of embedded strain gages and accelerometers attached to the foundation block and the upstream face of the dam. Vibration tests were conducted prior to the impact test and afterwards to determine natural frequencies and mode shapes. The initial velocity of the dam foundation system during the impact test was estimated at 25 inches per second. Internal strain time histories are presented and discussed. Damage to the model dam is compared to damage occurring in Koyna Dam during the Indian earthquake of 1967.