Examination of Geotechnical Properties of Structures of a Swamp Marginal Field Development in the Niger Delta

Abstract A geotechnical survey was carried out in a swamp location in Niger Delta, Nigeria. The primary aim of the geotechnical investigation is to gather crucial data on the physical characterisation of soil consistency in the area. The investigation was carried out by conducting site characterisation, laboratory testing, and data analysis. As a result, the geotechnical survey was conducted on land, swamp, and water (river). Two (2) boreholes labeled BH1 and BH2 were dug on land, each of which is 40 meters deep. The sample rate for BH1 and BH2 is 0.75 meters. Based on the sample rate of 0.75 meters, soil samples collected for each borehole were 53 samples. A total of 106 soil samples were collected for BH1 and BH2. Six (6) boreholes were dug over water, each at a depth of 20 meters with a sample rate of 1 meter given the total soil samples collected to be 120 samples. The boreholes were dug to determine the contents of the soil in each location. BH1 revealed a clay formation from the ground surface to a depth of 11.0 meters, and fine sand was encountered with a band of clay between 11 meters and 20.25 meters. Clay was discovered from 20.25 meters to the final 40.0 meters of the investigation. Similarly, on BH2, a formation of clay was observed from the ground surface to a depth of 34.50 meters, and fine sand was encountered at 34.50 meters and 40.0 meters depth. The moisture content of the clay layers ranges from 31-163 %, indicating that the clay has a low to high moisture content, as is typical of marine clays, with bulk unit weights ranging from 12.52-19.44 kN/m3. The liquid limit values range from 88-140 %, the plastic limit from 27-42 %, and the plasticity indices from 61%- 98 %. The sand's SPT N-values range from 6 to 14, indicating that it is loose to medium-dense in compaction. Furthermore, the riverbed boreholes revealed entirely clay formation with no trace of sand within the depth explored. This information is vital for designing the surface structures to be erected in this location.