Study of Soil Bearing Capacity of Various Sites with Designs of Various Structural Foundations

The study to determine the soil bearing capacity at Benue State Polytechnic Ugbokolo was carried out. Findings of the investigations revealed that the site is underlain by uniform soil materials based on the similarity of the profile and the plasticity properties with exceptions at locations C and E. The geotechnical properties established were a result of fine sand and predominant silt and clay content in the soil. The grading curves revealed high percentage of fine passing 0.075 mm BS standard sieve. The grain size ranged from 71.4 to 92.7 % passing 0.075 mm standard sieve with exception of samples from location 3 with grain size between 39.7 to 40.7 %. The liquid limits stand between 19.6 to 36.0 %, while the plasticity index (P1) falls between 11.3 to 20.2 % with exception of location C with average value of 4.0 %. The soils have exhibited moderate linear shrinkage recorded between 2.9 % to 10.7 %. Specific gravity obtained ranged between 2.19 to 2.74. The maximum dry density values obtained ranged from 1.90 to 2.14 g/cm3, with optimum moisture contents ranging from 9.2 to 14.2 % respectively. The apparent cohesion of the soils ranged between 5.0 KN/m2 and 31.3 KN/m2 while angle of internal friction is between 20 and 50. The allowable bearing capacity at the depth of 1m falls between 28.1 KN/m2 and108.9 KN/m2 at location B, whereas at 2m depth, the values were 42.2 KN/m2 at C and 99.5 KN/m2 at location D. For design of simple office complex, lecture halls and residential quarters, pad foundation is recommended at minimum depth range between 1m to 1.5 m link with ground beam below the ground level. Whereas, for more complex and high raised buildings within the Polytechnic, raft to pile foundation type may be required as design permits.