Consolidation properties and structural alteration of Old Alluvium

We present experimental observations and a conceptual model for understanding the compression swelling characteristics of Old Alluvium (OA) from San Juan, Puerto Rico. Prior studies have classified OA as transported, in situ weathered tropical soil whose intact macrostructure comprises cemented, pseudo-silt with mixture quartz grains aggregated clay particles. The aggregates include mixtures kaolinite smectite coated by Fe-oxides. Fe-oxides also act cementing agents between This study describes results series high-pressure (up to 63 MPa) incremental consolidation tests. Breakdown cemented structure is observed through changes properties, significant during unloading, an extraordinary reduction (i.e., three orders magnitude) coefficient consolidation. These are explained combination mechanical processes, comminution breakdown bonds, physicochemical linking pore fluid intra- inter-aggregate space. processes alter fundamental particle size distribution macro-porosity activate potential smectites concealed coating material. provide basis formulation constitutive describe macroscopic behavior offer framework understand response piedmont transported residual soils found elsewhere.