Accurate monitoring of displacements by liquid level instrumentation

摘要

Liquid level instrumentation is a commonly accepted and effective method to perform precision monitoring of vertical displacements during building and tunnelling activities. The liquid level sensors mounted to the structure detect the change of the hydrostatic pressure relative to a reference cell outside the zone of influence. The progress in sensor technology by using advanced digital correction technology has minimized the errors in the pressure measurement. Nowadays most errors are caused by the properties of the liquid and routing of the liquid-filled tubes. This paper discusses how the total error of the complete instrumentation can be minimized. The guidelines for installation of the liquid network are derived from theory as well as illustrated by case histories.