INFLUENCE OF STRUCTURE AND COMPOSITION ON RESIDUAL SOILS

The various formation factors responsible for differences in behavior between residual soils and sedimentary (transported) soils are described. The extent to which classical soil mechanics concepts derived from the study of sedimentary soils are applicable to residual soils is examined and discussed. It is shown that residual soils can be wrongly evaluated as problem soils simply because some aspects of their behavior do not conform to that of sedimentary soil. The relative importance of composition and structure in influencing residual soil behavior is examined by carrying out consolidation and triaxial tests on three residual soils, namely, a silt, a tropical red clay, and an andosol (volcanic ash soil). The need for an empirical or theoretical framework applicable to residual soils, in place of the stress history framework used with sedimentary soils, is discussed. © ASCE.