This paper intends to produce a compendium of geotechnical properties of major problem soils of Nigeria which have critical influence on the design, performance, lifespan, construction cost and maintenance of civil engineering structures. Apart from the well researched lateritic soils of Nigeria, the black cotton soils (BCS) of north-eastern Nigeria, clay shale of north-western Nigeria, organic clay prominent in Lagos and soft sedimentary deposits of the Niger-Delta areas of Nigeria are also considered. Significant geotechnical properties of major problem soils in Nigeria were discovered to be scattered in different publications, magazines, journals, conference proceedings, research papers etc. Consequently, it is the aim of this paper to collate, correlate, analyze and digitize these important geotechnical properties on digital map of Nigeria. A Geographic Information System (GIS) mapping software called ArcGIS will be used to generate isopleths in form of contours for these soil properties on map of Nigeria.

The compaction and consolidation characteristics of lateritic soils in Ikole area of Ekiti State were investigated. The investigation was carried out through laboratory tests on disturbed and undisturbed soil samples obtained from three borings (BH1, BH2, and BH3) of Holy Apostolic Nursery/Primary School, Ootunja, Ikole Local Government Area (L.G.A.) of Ekiti State Southwest, Nigeria. The soils are all lateritic and mostly fine-grained. Compaction tests indicate maximum dry densities of 2.05Mgm -3 , 1.78Mgm -3 , and 1.69Mgm -3 at optimum moisture contents of 14.3%, 20.7% and 19.6% for soil samples obtained from BH1, BH2 and BH3 respectively. Compression indices (Cc) obtained from oedometer tests are 0.04816, 0.03820 and 0.04318 while the calculated coefficients of volume compressibility (mv), are 1.308*10 -4 , 1.065*10 -4 and 1.093*10 -4 m 2 kN -1 for samples in BH1, BH2 and BH3 respectively. The unsoaked California Bearing Ratio (CBR) value at 2.5 mm penetration ranges from 42.10% to 92.40% and CBR value at 5.0 mm penetration ranges from 52.70 to 89.10% indicative of good materials for road subgrade, sub-base and base courses.

In earthquake geotechnical engineering, physical model experiments have proven to be significant and valuable in understanding the complex physics and engineering behaviors of prototype undrained soils in fields. An executed literature review indicated that large-scale physical model testing, such as shaking table (ST) and centrifuge devices, have associated advantages and limitations. The current paper presents the design, fabrication, and calibration of a 600N-capacity, small-scale, one-directional (1-D) laboratory ST device that enables quick and valuable assessment of soil liquefaction mechanisms. The dynamically induced porewater pressure (PWP) generation characteristics of sand soil mixed with different percentage weights of clay were evaluated and illustrated as a case study for testing the ST device’s performance. The east coast sand (ECS) of New Zealand’s North Island was mixed with different percentages of kaolinite clay to produce five variants of ECS (00, 05, 10, 20, 25, and 30). Three input sine wave ground motions of a constant frequency of 10 Hz and amplitudes of 2, 3, and 4 were applied and classified in the current study as low, intermediate, and moderate ground motions, respectively, to evaluate the evolution of the dynamic excess pore pressures in the soil samples. The results indicated that the clean ECS and mixed samples with lower clay content (ECS00, ECS05, ECS10, and ECS15) produced the highest excess PWP throughout the three shaking cycles, with higher tendencies of contraction and liquefaction properties. On the other hand, soil samples with a higher percentage of clay (ECS20 and ECS20) yielded the lowest PWP, with softening and dilative properties.

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This study assessed groundwater quality around an open dump municipal solid waste (MSW) disposal site at Ilokun, a village on the outskirts of Ado-Ekiti, Ekiti State, Nigeria. Three geotechnical boreholes and three water boreholes (tube wells) were drilled at intervals of 15m, 30m and 45m away from the disposal site. Soil samples were obtained near the top and at the bottom of the geotechnical boreholes. Tests carried out on these samples included the sieve analysis, specific gravity, bulk density, natural moisture contents, Atterberg limits, linear shrinkage, and hydraulic conductivity tests, and these were used to index and classify the soils at the landfill dumpsite. It was discovered that the soils belonged to the clay and clayey-sand USCS groups (CL and SC mainly). Groundwater samples were taken from the three water boreholes (tube wells), and physical, chemical and microbiological investigations carried out on the water samples and on water obtained from an existing hand-dug well in the neighbourhood of the dumpsite. The parameters obtained from the tests on the samples were compared with the Guidelines for Drinking Water Quality of the World Health Organisation (WHO) and the Nigerian Standard for Drinking Water Quality of the Standards Organisation of Nigeria. The water quality parameters determined included: the acidity (pH), temperature, electrical conductivity (EC), colour and odour, turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD), total dissolved solids (TDS), total hardness (TH), and contents of the constituents such as total iron, chloride, sulphate, nitrate, etc. The microbiological characteristics determined are the Total Bacterial Count (Total coliform count), and the presence of Faecal streptococci, Staphylococcus aeurus and Escherichia coli. It was discovered that the groundwater at the dumpsite has been heavily contaminated and unfit for human consumption or usage without appropriate treatment to render them potable and fit for domestic use.