Experimental Analyses on a Unique Protection System for Saving Workers from Collapsed Soil at Trench Excavations in Shallow Depth.

Abstract

Many cave-in accidents occur during trench excavations, leaving digging workers buried in collapsed soil even in shallow depths. A main cause of such accidents is the misunderstanding of stability. Typical earth support systems are heavy and stiff structures, so these are seldom used for shallow excavations. This study proposes a personal soil guard system to prevent labor accidents. This system has a simple structure with two sets of crossing frames and a pair of vertical sheets on located on either side to bear horizontal earth pressure from collapsed soil. This provides a protective space for personnel. It can be easily placed in trenches. Full scale model tests were carried out to investigate the function that blocks collapsed soil. An earth pressure from collapsed soil was measured at five different heights on a vertical wall that was placed at a distance from a model trench wall. The acting load after creep failure did not increase to a value that would cause failure of the frames and the sheets. And the supporting the shoulders and the toes by beams induced ductile failure, so the peak value of earth pressure on the sheets reduced. This study discusses a developed unique protection system for safer trench excavations in shallow depths.