Application example: Field Velocity Resistivity Probe (FVRP) for predicting pore pressure parameter B

Even though the pore pressure parameter B is essential to understand the soil condition, directly obtaining this value in a field test is difficult. The objective of this study is to propose a method for deducing B based on the elastic wave velocity measured in the field. In this study, the Field Velocity Resistivity Probe (FVRP), which has already been introduced in “Journal of Soil Dynamic and Earthquake Engineering” is selected to demonstrate the extension of the application. The wave propagation theory is applied, and B is rewritten in terms of the bulk moduli of the skeleton (K_sk), grain (K_g), and mixture (K_mix). This high-sensitivity parameter is ordered as K_mix, K_g, and K_sk. The bulk moduli of the skeleton and grain are determined by referring to a previously performed study, and the bulk modulus of the mixture is calculated using the compressional and shear wave velocity. B is close to unity with the average B value being calculated to be 0.9867. Even though the site is completely saturated, the reason for the small B value is the characteristic of the soil, which is highly compacted and in a consolidated condition. This result demonstrates that it is possible to determine B in the field through the elastic wave velocity, and the applicability of FVRP is excellent.