Abstract: In this paper, with free station setting scheme, a method to monitor the horizontal displacement of foundation pit slope is established. The method needs to observe the horizontal distance between monitoring points and reference points, and also needs the convergence value of the distance. In particular, a method for measuring the deep horizontal displacement on opposite sides by using electronic total station is given. Based on the principle of equal influence and the existing information of reference points, the principle and accuracy of foundation pit displacement monitoring method and distance convergence measurement are analyzed. The difference calculation and data processing of displacement monitoring points are realized. The accuracy of two distance convergence methods for monitoring horizontal displacement is discussed and applied to actual observation. The analysis results and engineering measured data show that the observation accuracy of the monitoring method meets the specification requirements, and the measurement efficiency is high, with good application value.

Key words: monitoring of foundation pit, free station, opposite-side measurement, distance convergence, soil inclination check