Advantages of Using a Seismic Piezocone Penetration Test for Analysis of a Single Screw In Situ Displacement Pile in Silty Soils

The determination of pile bearing capacity using the load–settlement relationship has been widely recognised as an effective means of directly determining the bearing capacity of a pile through in situ tests. Among the various techniques available for such investigations, the seismic cone penetration test (SCPTu) stands out as one of the most reliable. One key advantage of this test is its ability to measure the shear wave velocity (Vs) during the sounding process. In this study, the range of Vs values was examined specifically in silty soils. The data for this study were obtained from six SCPTu soundings and load tests conducted on seven screw in situ displacement piles. In addition to the four known correlations between the cone penetration test (CPTu) and Vs, three new correlations were developed, showing promising results for most of the soil layers examined. Moreover, a correlation between the normalised operative shear stiffness and the normalised pseudo-strain was established based on back-calculations using the results of static pile load tests. The findings of this study highlight the complexity of the correlation between CPTu readings and Vs in silty soils, emphasising the need for further research in this area.