Geotechnical Considerations for Foundation Design in Parts of Yenagoa, Bayelsa State, Niger Delta Nigeria

This research was to determine geotechnical properties of the subsoils in some part Yenagoa and environs obtain proper foundation design parameters, six towns local government area, Bayelsa state investigated. Six boreholes drilled laboratory studies soils samples were obtained from 0-20.25m deep. Subsurface soil profiles delineated followed by determination their index mechanical properties, including Atterberg limits, particle sizes distribution, undrained shear strength, box test consolidation coefficient. The general profile consists (from top bottom), , upper Silty clay horizon (0.0-5.25m thickness) soft firm for study areas, Medium silty (0.75 1.5m low clayey sand peaty (1.0m thickness between 3.0-4.0m) Igbogene Yenagoa, (3.0m Etegwe town lower (13.5 18.0m) fine medium coarse appear all Yenagoa. sub-soil show high plasticity, silt intermediate plasticity (CH, MI MH) according unified classification system results it shows that pad is more economical areas. Raft areas with Allowable bearing capacity layer ranges 23-128KN/m2 In view significant variations stratification engineering geological while data one location cannot be used as a basis nearby land. Axial load carrying 305, 306mm, 356, 360mm, 406mm, 600and 610mm diameter bore pile tubular driven steel cased piles respectively calculated Where rise building required various frequent causes collapse are result inadequate investigations subsoil, poor quality materials, work supervision.