Part 3Part 3

SECONDARY SECONDARY CONSOLIDATIONCONSOLIDATION

Typical plot showing Typical plot showing time rate of consolidationtime rate of consolidation for an for an organic silty clay. organic silty clay.

Secondary consolidationSecondary consolidation occurs due to continual occurs due to continual expunging of chemically-adsorbed pore water, at a expunging of chemically-adsorbed pore water, at a reduced, but more-or-less constant rate under a more reduced, but more-or-less constant rate under a more or less constant load (surcharge) or less constant load (surcharge)

Secondary ConsolidationSecondary Consolidation

The physical process believed to be responsible for The physical process believed to be responsible for secondary consolidation is sketched here; illustrating secondary consolidation is sketched here; illustrating how planar clay platelets are slowly re-aligned how planar clay platelets are slowly re-aligned perpendicular to the maximum principal stress, while perpendicular to the maximum principal stress, while expunging chemically-adsorbed moisture between expunging chemically-adsorbed moisture between the plateletsthe platelets

Raw secondary compression test data, as Raw secondary compression test data, as measured in a 14 week long test battery. measured in a 14 week long test battery. Samples of this sandy silt were taken from a a Samples of this sandy silt were taken from a a deep urban fill in San Bruno, CA deep urban fill in San Bruno, CA

Secondary Secondary Compression Compression

IndexIndex Relationship Relationship

between between natural natural water contentwater content and and secondary secondary compression compression indexindex, from Mesri , from Mesri (1973) and (1973) and NAVFAC DM-7.1-2NAVFAC DM-7.1-2

Note values for Note values for fibrous peatsfibrous peats are are the highestthe highest