Abstract: Tension wire alignment is commonly used in monitoring of horizontal displacement in the upstream and downstream direction of linear concrete gravity dams. The floating vessel should match with wire diameter and the distance between measuring points, or the size of floating vessels should be specifically designed. Otherwise, deflection and large draught of the floating vessel may cause system error of the tension wire alignment. For the case as the distance between measuring points is 35 m, the forces on the floating vessel are analysed, and accordingly, the vessel size is enlarged. On-site test on the accuracy of the measured values shows that it can meet the error requirements of the specifications.

Key words: tension wire alignment, float, distance between measuring points, size of floating vessel,  , wire diameter

摘要： 引张线常用于监测直线形混凝土重力坝上下游方向水平位移。引张线钢丝直径、测点间距与浮船尺寸要匹配，若上述参数超过规范规定，应专门设计浮船尺寸，否则将导致浮船偏转或下沉过深，产生引张线系统误差。针对引张线测点间距35 m情况，分析浮船受力，增大浮船尺寸，现场引张线的测值准确性检验表明，能满足规范的误差要求。

关键词: 引张线, 浮托, 测点间距, 浮船尺寸, 钢丝直径