Special Considerations in Design of Foundation in Problematic Soils

Abstract

The ability of a structure to withstand stresses starts from the nature of the soil on which it is built and the suitability of the foundation adopted for the corresponding soil condition. There are different types of problematic soils mostly encountered in practice such as expansive, collapsible and dispersive soils. Expansive soil is highly problematic due to its high rate of swelling and shrinking when they come in contact with moisture. They range from minor cases to severe cases. The minor cases are situations where the depth of the expansive clay is small and the foundation footing can reach beyond it to more stable strata. The severe cases are situations where the expansive clay is considerably deep and would require most preferably the pile foundation. For the purpose of this study, emphasis was placed on the expansive soil. This type of soil is common in North Cyprus due to the nature of its soil and the extremes in its weather conditions. The Haspolat region in the capital Lefkosa was studied. Relevant data such as soil test data, and other documents related to the research subject were obtained and analyzed. A reconnaissance survey was conducted based on an in depth interview with public officials, private sector entities and the inhabitants of Haspolat. Data was obtained from on the spot observation of the site and recorded for analysis. The extent of the depth of expansive soil in the soil strata required the use of raft foundations design in expansive soils. Its initial cost of construction is high but the maintenance cost of the building is minimal since the foundation resists any movement of the expansive soil which would have caused failure.