A new alternative geotechnical field testing device called the soil stiffness gauge (SSG), also known as GeoGauge (Trademark), exhibits particular promise for monitoring in situ soil stiffness during construction quality control. However, there has been only limited research on this device regarding its characteristics and limitations. The results of laboratory testing and a finite-element analysis (FEA) of the SSG are presented. Based on the FEA and the SSG measurement in the test box, the radius of measurement influence extends to 300 mm. For two-layer materials with different stiffness, the SSG starts to register the stiffness of an upper-layer material of 125 mm or thicker. The effect of the lower layer, however, may continue to be present even at an upper-layer material thickness of 275 mm, depending on the relative stiffness of the layer materials. Caution needs to be exercised in interpreting the results from the SSG when it is used on multilayer systems, especially those with geosynthetic separators. The presence of a geosynthetic separator between the layers may cause a stiffness decoupling of the layers.
Abstract