评判混凝土高坝地震灾变的关键问题探讨

Key problems for evaluating seismic catastrophe of high concrete dams

针对当前我国在西部强震区建设的一系列重大高坝工程的抗震安全问题,提出以"遭遇最大可信地震时不发生严重次生灾变"为确保重大工程抗震安全的战略重点,简要阐述相关工程背景、关键问题及目前已有的基础条件。指出其主要难点在于如何对溃坝的极限状态给出可操作的定量准则。认为基于损伤力学求解坝体-地基体系在强震作用下的损伤破坏过程是可行的。探讨了直接基于试验资料建立计入残余变形的损伤演化规律和力学模型的新思路,避免了损伤与塑性耦合,使分析更贴近实际、计算工作大幅度简化。通过对试件试验结果的实例分析,初步验证了本文方法的可行性。

With regard to the seismic safety of a series of high concrete dams currently constructed in the highly seismic region of western China,the strategic point to ensure the seismic safety of key projects was proposed,that is,to prevent severe secondary catastrophe during the maximum credible earthquake.The engineering background,main problems and existing essential prerequisites were described.It was put forward that the major difficulty was how to provide practical quantitative criteria for the critical state of dam failure.Evidently,a feasible way was to investigate the damage and failure process of the dam-foundation system by means of the damage mechanics.For this purpose a new concept of establishing the damage model with consideration of residual deformation directly based on the experimental data of materials without plastic-damage coupling was proposed.The proposed approach would make the non-linear analysis of the seismic response of the dam-foundation system more simplified and reasonable,and its feasibility was verified by the comparison between the numerical and experimental results of specimens.