Seismic performance evaluation of AAR-affected concrete gravity dams under main aftershock sequence

Abstract

Once the alkali-aggregate reaction (AAR) of the concrete dam occurs, the mechanical properties of the dam concrete will be degraded with the increase in the operating years. Besides, a large number of strong earthquake cases show that aftershocks usually occur after the main shock, and the evaluation of the seismic performance of concrete dams under the main aftershock has become the focus of research. This study establishes the overall damage mechanics model of the dam body and foundation. Degradation of concrete properties due to AAR and the influence of main shock and aftershock are considered to calculate the response of the dam-water and foundation coupled system at different ages. The overall seismic damage evaluation model of the dam is established to evaluate the seismic performance of the AAR-affected concrete dam with different operating years. The research results show that the damage of the dam is greatly affected when the AAR-affected of the dam concrete is considered under the action of earthquake. The overall damage index of the dam increases significantly with the increase in the dam's operating years. Within the period of 20 < T < 60, the growth rate of the damage index is the largest and aftershocks have different effects on the secondary damage caused by dams under different operating years. When the dam damage is light after the main shock, the secondary damage caused by the aftershocks on the dam is relatively minor. With the increase of dam operating years, the concrete strength decreases gradually while the secondary damage caused by aftershocks increases.