GEOTECHNICAL EVALUATION OF THE SOIL PROPERTIES BEHIND MODIBBO ADAMA HOSTEL AT FEDERAL POLYTECHNIC, DAMATURU

ABSTRACT This study presents a geotechnical evaluation of soils located behind Modibbo Adama Hostel at the Federal Polytechnic, Damaturu, with the aim of characterizing near-surface soil properties to support safe and economical foundation design for future construction. Four trial pits were excavated to a depth of 1.2 m, and representative soil samples were collected for laboratory testing in accordance with BS 1377 procedures. The tests conducted included natural moisture content, specific gravity, particle size distribution (sieve analysis), Atterberg limits, and direct shear tests. The results indicate that the subsoil is predominantly granular and classified as silty sand (SM) under the Unified Soil Classification System. Natural moisture content values are low, ranging from 1.32% to 3.75%, while specific gravity values fall between 2.46 and 2.56, which are typical of stable mineral soils. Sieve analysis shows low fines content, with approximately 11–14% passing the No. 200 sieve, confirming the sandy nature of the soil. Atterberg limit tests indicate non-plastic behavior across all samples, suggesting negligible clay content and low potential for swelling or shrinkage. Direct shear test results reveal very low cohesion (0.0–3.66 kN/m²) and friction angles ranging from about 24.81° to 27.09°, indicating that soil strength is governed primarily by frictional resistance. Allowable bearing capacity values range from 116 to 145 kN/m², demonstrating that the near-surface soils are capable of supporting shallow foundations for light to medium structures when proper compaction and site preparation are ensured. However, as the investigation was limited to a depth of 1.2 m, deeper subsurface exploration is recommended for the design of foundations for heavy or multi-storey structures.