Predicting Surface Subsidence from Basic Soil Tests

Standard soil index tests can be useful to predict near-surface subsidence of fine-grained soil resulting from initial wetting. The natural soil voids must be sufficient to allow a collapse of the soil structure and sufficient to allow saturation to develop a minimum consistency. By systematic sampling and laboratory testing investigations, the probability of subsidence was indicated for critical areas along the route of the proposed San Luis Canal in the San Joaquin Valley, Calif. Field ponding and laboratory consolidation tests provided observations of the amounts of subsidence for correlation with the results indicated by the sampling investigation.