Work in trenches exposes workers to many risks, including the risk of collapse, which is the greatest and most frequent risk but, unfortunately, is often underestimated. Despite the numerous recommendations and regulations in force, there is always a risk of landslides in earthworks.
Researchers from the National Institute of Occupational Safety and Health, Japan (JNIOSH) had developed and tested the Mini Pipe Strain Meter (MPSM) in their laboratory with Japanese soils to measure a potential increase in shear strain in the shallow subsoil of earthworks. Although the MPSM was successfully developed and tested to monitor trench stability and wall collapse in Japanese standard soils, its performance with other kinds of soils remained unknown. This assessment therefore sought to determine whether the MPSM would function effectively in sensitive clay, a standard soil of the Champlain Sea and the subsurface of more than 80% of the inhabited area of the province of Quebec. This assessment was made possible due to the concomitant execution of a more extensive study entitled Soil Classification and Selection of Shoring Systems for Trench Excavation.
In Japan, trials showed that the MPSM can help reduce the risk of injury due to collapse and constitutes a risk monitoring method. As for Quebec, the MPSM functioned well during in situ trials in standard Champlain Sea clay and made it possible to measure the increase in the risk of collapse during trench excavation. Other trials must, however, be carried out with other types of Quebec soils, as well as to assess its reliability and sensitivity regarding the impact of its positioning in relation to a trench or a slope.