Shallow Seafloor Sediments: Density and Shear Wave Velocity

Near-surface seafloor properties affect offshore mining and infrastructure engineering. Shallow sediments experience extremely low effective stress, consequently, these exhibit very in-situ density, shear wave velocity, stiffness. We combined data extracted from the literature with new laboratory field results to develop a comprehensive understanding of shallow sediments. First, we explored sediment-dependent self-compaction characteristics starting asymptotic void ratio at interface between water column sediment column. The depends on particle size shape in coarse-grained mineralogy pore fluid chemistry fine-grained clayey sediments; overall, correlates sediment-specific surface compressibility. Second, developed fork-type insertion probe measure velocity profiles depth. Detailed analyses confirm prevalent role stress Vs=?(?m?/kPa)?, inverse relationship ? ? parameters reveals that electrical interactions alter profile only high specific area shows ray bending affects computed velocities upper few centimeters (for geometry used this study). Probe causes excess pressure changes; ensuing time-dependent diffusion detected through changes can be analyzed estimate coefficient consolidation. Shear transients after provide valuable information for preclassification engineering design.