Fork blade-type field velocity probe for measuring shear waves

The reasonable assessment of the shear wave velocity of soft soils in the laboratory is difficult due to the soil disturbance. This study presents a new apparatus, the blade-type field velocity probe, FVP, which overcomes several limitations of commonly used shear wave measurement methods in the field. The shear wave velocity of the FVP is simply calculated by using the travel distance and the travel time without inversion process. The FVP are carried out in clay soils up to 30m in depth. In addition, the dissipation of excess pore water pressure is investigated. The shear wave velocity is measured every 10cm. The velocity profiles with depth show the consolidation of the upper part of the soft clay. The shear wave velocity approaches asymptotic value after 50 minutes later due to the dissipation of excess pore water pressure. This study suggests that the blade-type FVP may be an effective device for measuring the shear wave velocity with minimized soil disturbance in the field.