Experimental Researches in Defining Deformations by Free Station Method and Results Processing by Search Method

Abstract

This article proposes a method of monitoring the buildings stability with free station positioning which includes a geodetic monitoring technique with a free station. Processing and adjustment of data are proposed to be conducted with the search method by a specially designed software program. The sequence of monitoring is as follows. The location of the stations is chosen in such a way that each of them shows as many deformation and support points as possible and at least three points should be determined from any other station. It is preferable to choose stations approximately in the alignment of one pair of support points so that the planes of the marks being defined are perpendicular to the line of sight. Measurements of all horizontal angles, zenith, and slant distances to all visible reference points, and deformation marks are made at each station with an electronic total station. As a result, redundant measurements appear in the measurement scheme, which in turn increase the accuracy of the final result. The coordinates determination of the defining marks is performed by deducing the minimal sum of the measured angles deviations squares and of distances squares calculated from the preliminary coordinates of the marks taking into account the weights of the measurements. It is proposed to search for the objective function minimum with a search method using a specially developed program in the form of a macro in the Microsoft Excel software product which provides special features to accelerate the problem-solving process. The buildings deformation monitoring technique mentioned above was successfully tested at several sites.