Recent Progresses in Seismic Study on High Arch Dam in China

摘要

In this paper some recent research progresses achieved by the team supported by Chinese National Science Foundation including seismic input, structural responses and dynamic resistance as the mutually coordinated factors necessary for seismic safety assessment for high arch dams are briefly introduced. For seismic input, a new method of generating artificial accelerogram non-stationary both in amplitude and frequency and a more reasonable "finite fault method" to assess the Maximum Credible Earthquake (MCE) deterministically for dam site near the causative fault are stressed. For structural responses, an improved analysis of arch dams simultaneously considering all the factors such as: dynamic interaction of dam-foundation-reservoir, radiation damping of energy dispersion in far-field foundation, topography features and geological disturbances including all potential sliding blocks of arch dam abutments at both banks within the near-field foundation adjacent to dam, opening and slipping of contraction joints within dam and along the abutment sliding surfaces and dam base periphery during strong earthquake, and spatial variation of seismic input along dam foundation is developed. Also, a new conception from the break point of displacement responses of the integral dam-foundation-reservoir system under seismic action as the quantitative criterion for evaluating arch dam breach is suggested. For dynamic resistance of dam concrete, the effects of static preloads on the dynamic behavior of fully-graded dam concrete are investigated by testing, and the results are explained by the three-dimensional meso-mechanics analysis of the concrete specimen with real mix proportion. The dynamic failure mechanism revealed by the analysis was also observed by the X-ray computed topography (CT) technique. Finally, the high-performance parallel computation technique was successfully used in all these analyses.