关键词: 钢护筒, 检测, 三点坐标法, 精度分析

Abstract: A simple formula with three-point coordinate method to calculate the centre of circle is given,which is easy to program and calculate.To determine the third point position in the case of the certainty of two points,and three point optimal configuration is proven theoretically in detail,and accurate calculation as well as analysis are made from many aspects.The result indicates that three point configuration has larger influence on accuracy of the center of circle position;the measurement accuracy can be improved by selecting better configuration.It is operated quite well in the measurement of steel casing center position of Sutong Bridge.

Key words: steel casing, measurement, three point coordinate methods, accuracy analysis