Geotechnical Properties of the Subsoil for Designing Shallow Foundation in some Selected parts of Chanchaga Area, Minna, Nigeria

Abstract

he subsoil conditions of the study area were investigated by excavating nine trial pits from the existing ground level to 1.50 meter. Twenty seven samples were collected and analyzed. The soil is heterogeneous and two types were identified: brown, clayey, silty, gravelly sand and brown, gravelly, clayey, silty sand. The liquid limit ranges from 22.0% to 92.0%, the plastic limit varies from 7.47% to 51.10%. the plasticity index is of the order of 1.94% to 69.98%. The plasticity and shrinkage potential range from low to high. Montmorrillonite, illite, kaolinite and hallosite were identified with the latter being the most abundant. The soil cohesion (C) ranges from 9 KN/m2 to 27.50 KN/m2 while the angle of internal friction varies from 15 to 35. The compression index (Cc) is of the order of 0.11 to 0.74. Based on the field and laboratory results, shallow foundation (reinforced strip, pad or raft) can be adopted for lightly loaded structures. Construction techniques that should be implemented to minimize the effects of the shrinking and swelling clay are recommended.