Interpretation of Seismic Cone Penetration Testing in Silty Soil

Five Seismic Cone Penetration Tests (SCPT) were conducted at a test site in northern Denmark where the subsoil consists primarily of sandy silt with clay bands. A portion of the test data were collected every 0.5 m to compare the efficacy of closely-spaced down-hole data collection on the computation of shear wave velocity. A minimum of eight seismic tests were completed at each depth in order to examine the reliability of shear wave velocity data, as well as to assess the impact of the time interval between CPT termination and seismic test initiation on SCPT results. The shear wave velocity was computed using three different methods: cross-over, cross-correlation and cross-correlation “trimmed with window”. In the “trimmed with window” technique the latter part of the signal is clipped off by setting the amplitude to zero. The result showed that more closely-spaced test intervals actually increased the variability of the shear wave velocity and that time interval between seismic tests is insignificant. Correlation between shear wave velocity and cone resistance for silty soils were also determined and assessed relative to other published data on multiple soil types.