Experimental study on the dynamic response of a gravity dam model with longitudinal joints

A shaking table model test is conducted to study the dynamic response and failure mode of a 185 m high concrete gravity dam with longitudinal joints. Two longitudinal joints are provided in the dam model. A mortar mixture is used as the model material to satisfy the similarity requirements for the model test. The dynamic response and damage process of the dam are observed by inputting earthquake excitations with different ground peak accelerations (GPAs) and durations. It is observed that when the GPA is 5·32g (equivalent to 0·4g on the prototype) and the duration is 3·2 s, a crack appears at the top of the longitudinal joint that is close to the reservoir side and then extends to the slope of the downstream face. After 6·4 s, this joint is totally pulled apart and meets the crack that was previously formed. This study shows that when a strong earthquake occurs, the top of the longitudinal joint of the dam is more likely to suffer tensile damage, and the longitudinal joint will open because of the relatively low tensile strength. Based on the variations in strains, acceleration responses and dynamic characteristics, the possible crack location and damage process of the dam can be predicted.