一、前言拱坝的水平位移观测可以采用直伸三角网法,在重复观测时,又可以通过量高来测定。这样,直伸三角网法就成了“引张弦线法”。引张弦线法由于布设方便,施测简单,计算规律性强,精度较高,在重复观测的周期中,只要求测定水平径向位移时,更充分显示其优越性。二、布设特点及观测方法如图1所示,在拱坝的水平弧形廊道内,A、B二端点设于基岩上,其微小变形量有可能用倒锤或其它方法测定,因而可视为已知点。其间布设了水 I. Introduction Arch dam horizontal displacement observation can be used straight triangle method, repeated observations, but also by high volume to determine. In this way, straight triangulation method has become “lead wire method.” Because of the convenience of layout, the simple method of measurement, the strong regularity of calculation and the high precision, the method of enlarging string method only shows the superiority when measuring horizontal displacement only in the cycle of repeated observation. Second, the layout characteristics and methods of observation Shown in Figure 1, in the horizontal arched arch corridor, A, B set in the two ends of the bedrock, the small deformation may be measured using the hammer or other methods, and therefore visual Known point. During the laying of the water