Interrelationships between porosity and other geotechnical properties of slowly deposited, fine-grained marine surface sediments

Abstract

The pore volume, expressed as porosity or void ratio, of fine-grained marine deposits at the sediment surface (0–2 cm) is closely related to other geotechnical properties such as liquid limit, plastic limit, compression index, and specific surface area. Equations have been formulated for the interdependencies between (1) average porosity at the sediment surface ( n a) and liquid limit ( LL) [ n a = 100 (0.0378LL + 0.43) (0.0378LL + 1.43) ], (2) liquid limit ( LL) and specific surface area ( S g) [ LL = 1.01 S g + 46.5 if LL > 50], and (3) compression index ( C c) and void ratio at a stress of 0.01 MPa ( e' o) [ e' o = 3.352 exp C c]. From the relationship between geotechnical properties and initial porosity, the state of consolidation of surface sediments and the influence of bioturbation often lead to an increase in porosity (5–10%) and compressibility (up to 10%), and a decrease in the overconsolidation ratio (from 2–3 to about 1) at the sediment surface. The interrelationship between initial porosity and physical properties can be explained by the dependence of the geotechnical properties on the electrostatic forces between the particles and the adsorbed water around them.