Earth pressures in trench rescue shoring systems

Abstract

A three-dimensional parametric finite element analysis of the earth pressures on a shoring system used in trench rescue or as a shallow trench bracing was performed. Field monitoring of the deformation of an instrumented, full-scale braced wall section was also undertaken in two shallow trenches, one where the soil was mostly granular in nature and one where the soil was clayey, in order to gauge the effect of soil type on the shoring system performance. The study showed that the most significant effect on earth pressures was the strut loading. It was found that the magnitude and distribution of the soil pressure on shallow trench bracing was significantly different from that determined by the currently accepted one used for braced deep excavations. A method for calculating earth pressures on shallow trench bracing was developed that determines the earth pressures as a function of strut loading. It can be used to determine the maximum strut loading that can be used without causing a passive failure of the soil.