Scheme comparison analysis of the control travers arrangement in subway tunnel excavation

According to the practice of the shield subway construction,on the basis of open traverse used in traditional tunnel surveying,the paper puts forward three kinds of improvements namely,main-secondary station diamond traverse,main-secondary station quadrilateral traverse,and annular traverse,and analyzes the end pointerror by mathematic distortion method to simulate corresponding data.The results showed that the lateral error of the traverse increases with the traverse extending,the error increasing rate rises with the traverse extending;when using the improvments accuracies of these procedures errors become smaller obviously,the survey quantity for diamond traverse increases about 136.6% with open traverse,for quadrilateral traverse increases about 100%,for annular traverse increases about 118.3%;the accuracy of annular traverse increases about 35%,that of quadrilateral traverse increases about 53.4%,that of diamond traverse increases about 44.2%.In short,the quadrilateral traverse is the optimal scheme,and may be suggested to use in the practise.