【Author】YANG Huichen; WANG Haibo

【Abstract】 The Koyna concrete gravity dam is selected as an example to study the cracking damage caused by Koyna earthquake. The position and shape of the detached concrete block are computed to determine the stability of the detached block under earthquake and the influence of reservoir water after the shocks with the direct constraint method that is suitable for large deformation contact problems. The results show, that under the factual Koyna earthquake the block and dam remains stable and safe, and that under the design storage level the ultimate seismic capacity of block type Ⅰ is four times of the Koyna earthquake intensity, while type Ⅱ is eight times.

【Key words】 hydraulic structures; ultimate seismic capacity; large deformation contact problem; concrete gravity dam; detached block; afterschock