The geotechnical properties of soils influence the stability of construction materials and civil engineering structures. This study investigated the geotechnical properties of soil for design and construction of foundation from Kpansia in Yenagoa, Bayelsa State, Nigeria using standard techniques. Results obtained show that the Atterberg limit results reveal that the liquid limit ranges from 73.2% to 94.8%, the plastic limit ranges from 31.2% to 48.6% while the plasticity index values range from 34.8% to 50.1%. The cohesive soils(clays) are highly plastic (CH) in the Unified Soil Classification System (USCS) designation. The natural moisture content ranges from 63.5% to 87.9%. The particle size distribution analysis reveals that the sand is fine to medium to coarse grained and in a medium dense state of compaction and based on its coefficient of uniformity and gradation classifies as poorly graded (SP) by the USCS designation. The moisture content of the sand ranges from 12.6% to 19.2% while the bulk unit weight ranges from 19.6KN/m3 to 20.3 KN/m3. The angle of shearing resistance ranges from 260 to 330. The result of the undrained shear strength of the clay ranges from 16Kpa and 19Kpa. The clay is very soft to soft and exhibit medium to high moisture content. The strength test result indicates a material of low undrained shear strength, the coefficient of consolidation, Cv of the clay soil samples varies between 1.40m2/year and 2.89 m2/year. The coefficient of volume compressibility,Mv,for the same materials varies between 0.088 m2/MN and 3.548 m2/MN, generally indicating clay layers of high to very high compressibility. Raft foundation is best suited for these weak, soft foundation materials.
Keywords: Geotechnical Properties; Atterberglimit; shearing resistance; Undrained shear strength.
