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一、前言 大坝坝顶的位移观测具有极其重要的意义.因为坝基和坝体的工作状态能够通过坝顶位移发现出来,因此这项观测是监视大坝安全运行的重要手段. 在坝轴线为直线的情况下,坝顶的水平位移采用准直方法测定最为适宜.此法有时也用于拱坝.在准直法中,视准线法最为常用.但是,光学方法受大气湍流和折光等外界条件影响,特别是视准线较长时,效率和精度都很低.引张线法是较后出现的准直方
I. INTRODUCTION Displacement observation at the top of a dam is extremely important because the working conditions of the dam foundation and the dam can be found through the displacement of the crest, so this observation is an important means of monitoring the safe operation of the dam. Straight line, the horizontal displacement of the crest is most suitable for the determination by the collimation method. This method is also sometimes used for the arch dam. In the collimation method, the line-of-sight method is most commonly used. However, the optical method is affected by atmospheric turbulence and refraction External conditions, especially when the line of sight is longer, the efficiency and accuracy are very low.