Field test of the JNIOSH Mini Pipe Strain Meter as a safety alert system during trench work

Case studies reveal that workers do not always have time to evacuate the excavation because 1) the time between the completion of the excavation and the onset of the cave-in causes the workers to misinterpret the stability of the soil mass, 2) creep phenomena occur before the cave-in and 3) ground movements are initially too small to be detected by simple observation. [...] Therefore, the focus of the present expertise was to determine whether the MPSM would perform effectively in situ in sensitive clay, a typical soil of the Champlain Sea, which makes up the subsurface of more than 80% of the inhabited territory of the province of Quebec. [...] Case studies reveal that workers do not always have time to evacuate the excavation because 1) the time between the completion of the excavation and the onset of the cave-in causes the workers to misinterpret the stability of the soil mass, 2) creep phenomena occur before the cave-in and 3) ground movements are initially too small to be detected by simple observation. [...] (2012) explained that “the standard deviation of the measurements between the two epochs can be quite high, depending on multiple factors, such as the quality of the TLS data sets, the density of the points, the existence of vegetation, the roughness of the relief, the quality of the alignment between the scans, the relative or absolute position of the TLS and the variation of the surface of the t. [...] A radius (R) between the bucket and the center of rotation of the upper structure of the excavator was kept at about 3.5 m so that a constant value of an acting load (F) was applied through the acting area of the bucket (A).