Development of seismic CPT for evaluating in-flight soil properties in centrifuge model test

While performing centrifuge test, it is necessary to carry out in-flight soil characterization in order to fully characterize the soil. A Seismic Cone Penetration Testing (SCPT) system was developed for quantitative evaluation of soil strength and stiffness variation with depth by measuring the cone penetration resistance (q_c) and the shear wave velocity (V_s). In order to verify the applicability of the developed system, a centrifuge model test using silica sand was performed. This paper presents the testing procedure, typical signals from seismic cone and data analysis method. The refracted ray path method was used for the SCPT data interpretation because the first arrival travel time is determined by a shear wave propagating along a downward curved ray path rather than a straight path due to the effect of increasing vertical stress. The Vs profile with depth is verified through comparison with bender element test results. The results show that the SCPT system used during the centrifuge testing is an appropriate technique for measuring the in-flight soil properties.