重力坝均匀冲击破坏模型试验研究

Damage model tests for a gravity dam under uniform shock load

采用逐级递增循环均匀冲击加载方式,研究重力坝模型的破坏特征、自振频率与模态振型变化规律、最大加速度响应与冲击能间关系。试验表明,随着冲击能的增加,坝体依次出现砂浆掉皮、掉皮区扩大、上部细小裂缝、上部裂缝扩展及贯通、上部坝体断裂、中部细小裂缝、中部裂缝扩展及贯通、中部坝体断裂;自振频率随冲击能增加而降低,冲击后模态振型前二阶变化较小,第三阶变化较大;冲击作用下坝颈最大加速度响应最大;响应趋势与损伤程度有关,冲击能逐渐增加,无损伤或损伤较轻部位响应依次为增加、减小、变化不大或略有增加,损伤较重部位依次为略有降低、增加、减小、变化不大或略有增加。

Adopting cyclic uniform shocks with increase in amplitude, the failure features, the change laws of natural frequencies and modal shapes, and the relationship between the maximum acceleration response and impact energy of a gravity dam were studied. The test results showed that phenomena including cement mortar scaling, scaling region enlarging, minor cracks at upper part, upper part cracks enlarging and penetrating, upper part breaking, minor cracks at middle part, middle part cracks enlarging and penetrating, and middle part breaking appear in proper order; natural frequencies decrease with increase in impact energy; changes of the first two modal shapes are smaller after shock, the third modal shape has a larger change; the location of the maximum acceleration response is dam neck; the change tendency of the maximum acceleration response is related to the damage level; with increase in impact energy, the acceleration responses at locations with no or slight damage, increase, decrease, change slightly or increase slightly in order; the acceleration responses at locations with a more heavy damage decrease, increase, decrease, change slightly or increase slightly in order. © 2017, Editorial Office of Journal of Vibration and Shock. All right reserved.