Measurement of Ground Heave Due to Horizontal Borehole Instability during Horizontal Directional Drilling Experiments in Sand

摘要

Ground movement due to blow-out (unconfined shear failure) can develop when conducting pipe installation by horizontal directional drilling through sand, and this can endanger pavements, sidewalks, and other buried infrastructure. This paper presents and compares the three methods used to monitor ground movements in experiments conducted at Queen's University to investigate horizontal borehole instability due to excessive mud pressures. Particle image velocimetry is a method widely used to monitor displacements in different geotechnical and structural applications, and a new post-processing procedure for the Geo-PIV software is introduced to reduce displacement errors associated with application to three dimensional problems. SfM-MVS (structure for motion and multi-view stereo) and LiDAR (light detection and ranging) was also used to record surface geometry before and after each experiment, to permit comparisons with the deformation data from Geo-PIV. The advantages and disadvantages of these monitoring methods are then discussed. Finally, the progressive development of ground heave with changes in mud pressure in the horizontal borehole will be illustrated. These findings can be of significant value for specialists analyzing ground heave during drilling projects through sand.