Geotechnical characterization and facies change detection of the Bogacay coastal plain (Antalya, Turkey) soils

Abstract

The Bogacay Plain is well known tourist site in Turkey, which is famous for its wide beaches. However, almost 60% of the area is now occupied by buildings, and some of the high-rise buildings suffer from foundation settlement and tilting. Soils of the plain are of lagoonal origin; all of the facies which are typical of the lagoonal environment are present in the geological profile. Because of variation in grain size and development of a weathered crust, the fine-grained soils of the central-lagoon environment are highly variable with regard to their engineering properties. The compression indices of clays range from 0.25 to 0.55 and correlate relatively well with initial void ratio, liquid limit, and moisture content. Over consolidation ratio varies between 1.4 and 10 and decreases from the surface down to the base of the weathered-crust zone. The undrained shear strength of clays decreases with depth for the first 6 m; this behaviour is because of apparent overconsolidation in the weathered-crust zone. Sedimentary facies and their boundaries can be detected using CPT data; moreover, for profiling and facies-boundary detection, SPT and seismic sounding are not as effective as CPT.