Does Lateral Stress Really Influence Settlement?

Abstract

Construction innovations such as compaction grouting, the use of a reverse pitch section for installing augercast piles, and the use of beveled rammers to compact rammed aggregate piers, all emphasize the development of lateral in situ soil stress. The question posed herein is whether lateral stress in itself may reduce settlement, aside from any influences through densification or increased skin friction. Stress paths for a normally consolidated soil that is laterally stressed to the passive limit, then vertically loaded, gives a sequence of Mohr circles that indicates a shift from consolidating to near-linear-elastic behavior. The change requires and appears to depend on reversals in the directions of intergranular friction. As these reversals should occur with very little strain, they do not require that the soil be significantly compacted. Excess pore pressures that may develop should be relieved with the aggregate pier method of soil reinforcement. The reinforced soil layer should distribute stresses to the underlying soil in a manner that is similar to the action of a highway base course.