精密弦矢导线法与边角导线法比较浅析

THE ANALYSIS AND COMPARISON BETWEEN THE METHODS OF STRING-ARROW AND LATERAL-TRIANGULATION LEAD

精密导线法分为边角导线法和弦矢导线法 ,是监测水库拱坝水平位移的重要方法。弦矢导线法是根据导线边长变化和矢距变化的观测值来求得坝体的实际变形量 ;边角导线法则是根据导线边长变化和导线的转折角观测值来计算坝体的变形量。比较分析了边角导线法和弦矢导线法的设计原理与计算方法 ,认为精密弦矢导线法与精密边角导线法相比具有如下优点 :(1)复测简单、速度快、劳动强度小 ;(2 )精度高且稳定 ,不受折光等外界条件影响 ;(3)便于采用数字化遥测 ,可为实现位移值计算自动化奠定良好基础。

The method of precision lead is one of the efficient ways to survey the horizontal displacement in a reservoir's arch dam. It is divided into two ways of string arrow lead (SAL) and lateral triangulation lead (LTL). Calculating actual deformation of SAL is based on the length variable of the lateral and string,while LTL is based on the length variable of the lateral and included angle variable of two laterals.This paper has made some analysis and comparison according to design principle and calculation of two methods. The result is that SAL has higher precision than LTL when used in an arch dam. The performances are bellow: ①more convenience for repeated survey, higher speed and lower labor intensity; ② higher stable precision, easy to avoid the harmful influence from the environment, such as light, air current, etc. ③ convenient for automatic survey and computer figure process.