Foundation integrity assessment of failed buildings in Ehamufu and Aguamede, South East Nigeria

The failure of civil engineering structures especially buildings by severe cracks, partial, or complete collapse have kept the natives of communities in Aguamede and Ehamufu (Southeastern Nigeria) communities in a bothered state. Detailed geotechnical techniques and X-ray diffraction analysis were applied to investigate the soil samples from the study area. Geotechnical results revealed that the soil of the area have high clay content (62.78–82.37%), high liquid limit (48–54%) with a plasticity index of 20–28%, high moisture content (25.06–27.28%) and low permeability of 2.21 × 10(–8)–1.74 × 10(–6) (m/sec) which hinders drainage. Maximum dry density values were in the range of 1.73–1.98(g/cm(3)) with an optimum moisture content of 17.5–19.8% and average specific gravity of 2.5 (mg/m(3)). Shear strength test revealed high cohesion (32–36.4 KN/m(2)) to low angle of intergranular friction (10–12°). Coefficient of consolidation ranges from 0.04 to 0.94 m(2)/year were observed. Coefficient of volume compressibility values were in the range of 0.00012–0.00028 m(2)/kN and showed that the soils are highly susceptible to compression as the foundations are underlain by an inadequate soil layer that is vulnerable to settlement in amount ranging from 0.553–0.654 mm/year at load pressure of 400 kN/m(2). X-ray diffraction analysis revealed that the mineralogy of soil in the study area consist of quartz (89–89.7%) and kaolinite (10.3–11%). Statistical analyses showed that specific gravity, cohesion, clay, silt, NMC, PI, sand, LL and phi have strong interrelation in the correlation table. Comparing the geotechnical parameters from the study area with the Nigerian specification for constructions, it is shown that the study area has poor foundation materials.