IJSRP, Volume 4, Issue 3, March 2014 Edition [ISSN 2250-3153]
Ngerebara Owajiokiche Dago, Warmate Tamunonengiyeofori
Subsoil investigation was conducted at Unyeada in Andoni Local Government Area, in the Niger Delta for the purpose of designing a suitable foundation for a water tank structure. Field and Laboratory investigations show that the topsoil is underlain by a Loose clayey sandy Layer (about 6m thick) with Phi < 280, overlying a soft clay with cu of about 12KN/m2. Underneath the soft clay is medium dense sandy layer with Phi between 300 and 320. The allowable bearing capacity profile of the sub-surface shows a minimum bearing Capacity of 79.8KN/m2. Settlement predictions based on a loading of 300KN/m2 indicated a settlement of 26mm. The bearing capacity analysis for the underlying soils is limited to the near surface sandy clay. In general, the sandy clay is partially saturated and when tested in unconsolidated and undrained conditions, exhibits both cohesion of 0.00kPa and angle of internal friction of 280for its shear strength characteristics. However, the frictional component of shear strength is neglected for the clay encountered within normal founding depths for shallow foundations when estimating ultimate bearing pressures for the clay. The placement of a Raft foundation on a compacted granular material is suggested for the water tank stand.