Introduced hereby are exchange of the result from survey before construction, and the repetitive survey of the centerline and setting out of edge line, especially the layout of the pile fender and mile post, check up and addition of bench marks, survey of the longitudinal and cross sections, etc.

The bench marks and the touching - pipeline monitoring points isnt.

The problems such as burying of bench marks and settlement observation points,observation method,determining of precision criteria etc.

Analysis of the Benchmark Stability Based on Matlab;

The conclusion for the settlement experiment of benchmarks in this thesis, is that the height changes of buried-points laid in insaturate-moistured and deposited sandy soil nearby the Song.

The paper discusses the height checking network establishment,surveying and accuracy analysis,introduces the practical use of river crossing levelling by theodolite tilt angle method,and analyses the causes of height change of northern benchmarks along the river.