Measurement of Stress and Strain in an Unsurfaced Haul Road at a Soft Clay Site in Scotland

Abstract

Strain coil sensors and pressure cells were installed in relatively large numbers in a trial haul road, constructed in Scotland, that was subjected to controlled trafficking. The instruments and their installation are described and their operation is discussed. The strain coils are shown to give a reasonably good measurement of both transient and plastic strains when placed in both unbound aggregate and cohesive subgrade soil, and data collection is shown to be facilitated by a new electronic apparatus. Sensors also have good survivability and are cheap to make and install. Pressure cells performed somewhat less well, because of apparent environmental survivability defects and inherent difficulties of installation and operation resulting from inhomogeneity generated in the surrounding ground. The cells were unable to monitor any (small) self-weight stresses.