中文摘要：

我国在建的几个特高拱坝施工期均不同程度地出现了裂缝,本文从典型裂缝的成因和机理分析出发,探讨了预防或减小施工期不同裂缝的措施与方法,包括温度梯度控制、冷区高度控制和水管冷却模式选择等。施工期大多数裂缝由内外温差引起,这类裂缝可通过表面保温和控制内部温度来解决,而由基础温差和上下层温差引起的二冷末裂缝,应通过温控和中期冷却的方式减小二冷降温幅度和通过合理设置竖向冷却梯度的方式解决。另外,针对特高拱坝同冷区方案进行对比分析,结果表明,不同冷区方案的差异主要体现在底部封拱后所带来的拱向应力差异,对顺河向的应力影响较为有限。

英文摘要：

Cracks of different extents were found in several super-high dams under construction in China.This paper analyzes the mechanism of typical crack development,and discusses the measures and methods of preventing or lowering the risk of different cracking at the construction stage,such as temperature gradient control,cooling height control,and selection of water cooling mode.Most of the cracks were induced by an inside-outside temperature difference of a dam under construction;they could be avoided by heat preservation and inside temperature control.The cracks that often appeared at the end of second cooling were induced by the up-down temperature variation;they should be controlled by adding a middle cooling to keep the vertical temperature gradient within a proper range.In this study,the methods of one simultaneous cooling zone and two simultaneous cooling zones for a super-high arch dam were compared.The results show that a major difference in the axial stress caused by the envelope arch at the bottom,while the difference in the stream-wise stress is nearly negligible,indicating little improvement on this stress by the two zones method.