Field Test of Temporary Excavation Wall Support in Sensitive Clay

Abstract

This paper presents the results of a field experimental study carried out to investigate the soil pressure on a temporary flexible trench shoring in sensitive clay. The installation, instrumentation, and field test procedures are presented for two trench boxes “stacked upon each other” in conformity with United States OSHA regulations and placed inside the trench to cover the total 6 m (20 ft) depth of excavation. The field test results are presented in terms of soil pressure distribution along the depth of excavation with and without a 45 kPa surface surcharge next to the edge of one side of the trench. The results reveal the potential use of an existing excavation and trench shoring system in this type of soil and validate its performance with published theoretical results. In terms of soil pressure distribution along the trench, the analytical formulae generally underestimated the experimental values for the type of sensitive clay considered in this study.