Application of Geophysical and Geotechnical Approach to Determine the Soil Bearing Capacity of Calaro Sub-Surface

Volume 1 - Issue 5

EA Obeten¹, JG Egbe²* and DE Ewa²

Received: December 04, 2018   Published:December 13, 2018

DOI: 10.32474/OAJESS.2018.01.000123

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Abstract

Geophysical and Geotechnical investigations were carried out on the proposed New Oil Mill at Wilmar Calaro Oil Palm Estate in Awi- Akamkpa of Cross River State. Five borings were carried out at the depths of 42.3 m and 3 m at intervals of 1m and 4.7 m respectively. The samples were taken to the laboratory for Sieve analysis, compaction test, California Bearing ratio test, plasticity index, maximum dry density, unconfined triaxial test, and shrinkage test to determine the bearing capacity of the soil. The results revealed that the subsurface displayed good bearing capacities characteristic of (1.5m and 467.20KN/m²). Settlement predictions based on a loading of 100KN/m² indicated a settlement of 1.68 mm. Hence, the subsurface is adjudged to be suitable for the proposed construction with the expected superstructure. Seismic refraction was also carried out in the locations the geotechnical borings were made using a 12channel seismograph (Teraloc) model DPU 411 to determine the bearing capacity of the subsurface. The five selected locations that were investigated shows that the hammer source penetrated the first three layers of the earth. A software seislmager was used to analyze the data. The range of Velocities for the first three layers were 276 m/s to 1148 m/s, 544 m/s to 2270 m/s and 1134 m/s to 5368 m/s, their depths to bottom were 1. 7 m to 8.1 m and 7.2 m to 13.5 m and the shear modulus (μ) of 0.97 x 108N/m², young modules (E) of 2.06 x 108N/m² to 331 x 108N/m², Lame’s constant (λ) of 0.14 x 108N/m² to 927 x 108N/m² and Poisson ratio (σ) of 0.01 to 0.3 were calculated, the soil identified in the survey area were mainly sand, clay, shale, gravel, and granite. Seismic refraction and geotechnical results show a good agreement that the soil is well consolidated, and it is suitable for the expected deep foundation building.

Keywords: Settlement; Seismograph; Shear Modulus; Sub-Surface; Geophysical; Geotechnical

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