Humid tropical expansive soils of Trinidad: Their geotechnical properties and areal distribution

Expansive soils occur in abundance in the central and southern regions of Trinidad and contribute to extensive landsliding, and building and pavement damage. Since there is little documentation available in this country on these soils, this study is undertaken to develop the necessary data to cope up with the deleterious nature of these soils. Disturbed and undisturbed soil samples are obtained from a large number of sites covering both regions, and tested for grain size, classification, suction and potential swell measurements. Based on the results of these tests a modified plasticity chart and a multi-parameter criteria are presented to identify the expansive soils according to the degree of their expansivity. The results have shown that these soils exist in an overconsolidated state and their in situ water contents are high and are generally at plastic limit. As a result their potential swelling capability is apparently somewhat restrained. Further, a hazard map is presented showing areas of potential danger from expansive soils to light engineering structures.