丹江口工程左岸连接坝段三维动力响应分析

丹江口工程是南水北调中线工程的水源工程。左岸连接段混凝土重力坝与土石坝呈正交连接，是典型的三维问题。过去只作过平面分析。为了确保该工程的安全，又进行了三维动力分析。应用子空间迭代法解动力方程的特征方程，得出坝体的自振频率和振型；然后进行反应谱分析，得出地震荷载和坝体各振型的应力响应；最后把各振型的应力响应进行组合，得出坝体的最大应力响应。库水与坝体的相互作用是在上游坝面引入附加质量来考虑的。为了评

3-D dynamic analysis for Danjiangkou dam section connecting embankment

The Danjiangkou reservoir is the water source of the Middle Route South-to-North Water Transfer Project. The connection between the concrete gravity dam and the embankment on the left side is of a normal angle, thus the behavior of this connection is a typical 3-D problem. In the past, 2-D analysis was carried out for the connection section. In order to ensure the safety of the Danjingkou project, 3-D dynamic analysis has been conducted in addition. The natural frequencies and the vibration modes of dam body are obtained by solving the dynamic characteristic equations using the subspace iteration method; the earthquake loads and the response stresses of various vibration modes of dam body are then calculated by using the response spectrum analysis; finally, the combinations are made on response stresses of various vibration modes to obtain the maximum response stresses of dam body. The interaction between water and dam is modelled by introducing some centralized masses on the upstream dam surface. In order to assess the dam's vibration-proof behaviours, the degrees of safety for various parts of dam body are calculated, as judged by Drucker-Prager yield criterion. The calculations show that the response displacements for various order vibration modes are smaller; the factor of vibration-proof safety for clay core wall are all more than one; at some spots on the crest of connection section cracks would occur under actual earthquake, but these would not lead to any significant damage.