Geotechnical Characterization of Sub-Soil within Ladoke Akintola University of Technology, Ogbomoso-Nigeria

Abstract

This study investigates geotechnical characterizations of sub-soil within LAUTECH community as well as the relevant engineering characteristics were evaluated to enable appropriate foundation design. Nine (9) soil samples were obtained at 1.0, 2.0 and 3.0m using boring methods from three locations: LAUTECH Security Unit,(LSU:N8°5.977; E4 10.112), LAUTECH Chapel, (LC:N8° 07.756; E004’ 12.981), and LAUTECH Software Building, (LSB: N8° 09.986; E4’15.781′). The samples were subjected to visual examination and subsequently geotechnical tests in accordance to British Standards BS 1377, (2000). The tests were Specific Gravity (SG), Particle Size Distribution Analyses (PSDA), Liquid Limit (LL), Plastic Limit (PL), and Compaction test using British Standard Light (BSL) compactive effort, California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS). The samples from all the locations varied from light brown sand to reddish gravel. The SG values for LSU, LSB and LC were (2.66, 2.63, 2.37); (2.68, 2.59, 2.60); (2.48, 2.67, 2.43), respectively, while the grain size varied from fine to coarse. The LL values obtained for LSU, LSB and LC were 38.0, 37.0, 44.0% and 34.0, 32.0, 35.0%, while the corresponding PL values were 21.0, 26.0, 28.0%, and 24.0, 20.0, 21.0%, respectively. The maximum dry density values were (1.94, 1.66, 1.38; 2.38, 2.23, 1.93; 2.02, 2.12, 1.77) g/cm’and OMC values were (13.5, 17.2, 19.2; 11.6, 16.4, 13.8; 12.1, 9.4, 14.0) %, respectively. The ranges of CBR values for the soaked and un-soaked samples for LSU, LSB and LC were 26.0 – 38.0; 36 – 52; 26.0 – 59.0%, and 61 – 74; 71 – 85; 56 – 70%, respectively. The UCS values for the disturbed and undisturbed samples were (363 ~ 865; 497 ~ 694; 202 ~ 596) kN/w and (396 ~ 831; 427 ~ 726; 236 – 732) KNAm’. The samples obtained from LSU and LC were classified as A-2, while LSB sample was classified as A-4 and A-6. The samples obtained at (1m) depths within LAUTECH Community are suitable as sub-grade materials. Hence, stabilization is recommended at further depths prior to their applications for engineering purposes.