Measurement of landslide displacements using a wire extensometer

A continuous recording of landslide displacements is often required in orde r to better understand the complex relationship between the triggering fact ors and the dynamics of the movement. In this paper, we discuss the perform ance of the borehole wire extensometer and the interpretation of its result s. The analysis for the case of a translational slide shows that the displa cements measured with the wire extensometer are systematically smaller than the movements observed at the ground surface. A relationship between the w ire readings and the horizontal component of the landslide movement has bee n established by means of three equations representing different stages of the wire displacement within the borehole. The applicability of these equat ions and the interpretation of the wire extensometer readings have been suc cessfully checked at two landslide sites: Vallcebre in the eastern Pyrenees and Alvera in the Dolomites, (C) 2000 Elsevier Science B.V. All rights res erved.