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为了发展国民经济,充分利用水资源和水能资源,我国在建和拟建的十多座高拱坝高度在200m以上,达到300m量级,无论是建设规模还是建设难度均为世界之最,存在不少具有挑战性的科学技术问题。它们大多建于西部高山峡谷地区,地形地质条件复杂、环境恶劣、地震烈度高,严重威胁高拱坝的安全。因此,高拱坝在灾变条件下的破坏机制和安全评估一直是坝工专家高度关注的问题。高拱坝的整体破坏机制和相应的分析方法是拱坝安全性研究的主要内容之一,但至今对整体破坏的力学机制没有统一的认识,也没有一个具有力学理论基础的可行方法。该文简略介绍拱坝现行的安全性校核方法,指出存在的问题。根据力学系统的稳定性理论,揭示了高拱坝整体破坏的本质是稳定性问题。基于其破坏过程中荷载位移曲线的特征,论证了高拱坝的失稳破坏是一种由于材料非线性引起的、始于强度破坏的物理不稳定现象,失稳形式为极值点失稳。展示了拱坝整体稳定性的一些分析方法,指出基于弹塑性渐进分析的间接法是目前进行拱坝整体稳定性的可行方法,并通过物理模型试验验证了数值模拟的正确性;同时,也指出该方法并非直接从力学系统稳定性理论导出,科学的分析方法与失稳破坏判据应通过物理扰动方程的研究得到。揭示了非线性对拱坝极限承载能力的影响,理想弹塑性本构和几何线性处理均会高估拱坝的极限承载能力,偏于不安全。给出应用突变理论确定大坝极限承载能力的条件。提出确定极限承载能力的最大弹性变形能判据。
In order to develop the national economy and make full use of water resources and hydropower resources, over a dozen high-arch dams under construction and to be built are above 200 meters in height and reach the order of 300 meters. Both the construction scale and the construction difficulty are the highest in the world, Many challenging scientific and technological issues. Most of them are built in the western alpine gorge area. The topographic and geological conditions are complex, the environment is harsh and the earthquake intensity is high, which seriously threatens the safety of high arch dams. Therefore, the failure mechanism and safety assessment of high arch dam under catastrophic conditions have always been a great concern to dam experts. The whole failure mechanism and corresponding analysis method of high arch dam are one of the main contents of the research on safety of arch dam. Up to now, there is no unified understanding of the mechanical mechanism of overall failure and there is no feasible method with mechanistic basis. The article briefly introduces the current safety assessment methods of arch dam and points out the existing problems. According to the stability theory of mechanics system, it reveals that the essence of the whole damage of high arch dam is the stability problem. Based on the characteristics of load displacement curve in the process of failure, it is proved that the failure of high arch dam is a kind of physical instability caused by material nonlinearity, which is caused by the failure of strength. The instability form is the extreme point instability. Some analysis methods of the overall stability of the arch dam are presented. It is pointed out that the indirect method based on elasto-plastic progressive analysis is a feasible method for the overall stability of the arch dam. The physical model test verifies the correctness of the numerical simulation. At the same time, The method is not directly derived from the stability theory of mechanical systems. The scientific analysis methods and the criteria for failure of failure should be obtained through the study of physical perturbation equations. The influence of nonlinearity on the ultimate bearing capacity of arch dams is revealed. Both the ideal elasto-plastic constitutive and geometrical linear processes will overestimate the ultimate bearing capacity of arch dams, which is not safe. The condition of determining the ultimate bearing capacity of dam using the catastrophe theory is given. The maximum elastic deformation energy criterion for determining ultimate load capacity is proposed.