Effects of Density and Moisture Variation on Dynamic Deformation Properties of Compacted Lateritic Soil

A series of repeated load triaxial tests were conducted in this study to investigate the influences of compaction density and postcompaction moisture variation on the dynamic elastic modulus (Ed) and plastic permanent strain (PPS) of compacted lateritic soil. Specimens were compacted at optimum moisture content (OMC) and three degrees of compaction (90%, 93%, and 96%). Then the specimens were dried or wetted to different moisture contents (OMC, OMC±3%, OMC±6%, and OMC+9%) prior to testing for Ed and PPS. Results show that moisture content has greater influence on the Ed and PSS than compaction degree, and the increase in moisture content leads to a decrease of Ed and an increase of PPS. Furthermore, an empirical relationship between Ed and applied cyclic stress (σd) is developed that incorporates density and moisture variations. Three different evolution types of PPS with number of load cycles, plastic stable, plastic creep, and incremental collapse, are identified as the increase of moisture content. In addition, the critical dynamic stress (σdc) separating stable and unstable deformation is determined based on the shakedown concept. The envelope curves of σdc-moisture of lateritic soil with different degrees of compaction are also determined to provide reference for the pavement design.