Poisson’s Ratio of Surface Soils and Shallow Sediments Determined from Seismic Compressional and Shear Wave Velocities

U. E. Essien¹, A. O. Akankpo^2*, M. U. Igboekwe³

¹Department of Science Technology, AkwaIbom State Polytechnic, Ikot Osurua, Nigeria.
²Department of Physics, University of Uyo, Uyo, Nigeria.
³Department of Physics, Michael Okpara University of Agriculture, Umudike, Nigeria.

DOI: 10.4236/ijg.2014.512125                

Abstract

This paper presents the results of seismic compressional, P- and shear, S-wave measurements carried out on the unconsolidated top-soil at the different locations of the study area to determine Poisson’s ratio. In this work, seismic refraction data is used to determine Poisson’s ratio as an aid to engineering foundation. A 12-channel seismograph with signal stacking ability was used together with high frequency (100 Hz) geophones on the top-soil. The geophone intervals were set to 5 m at the all locations. In all the locations, V_p/V_s ratio ranged from 1.0289 to 1.4185 for the top layer. V_p/V_s ratio in the second layer ranged from 1.0512 to 1.5834. The Poisson’s ratio for the first layer ranged from -8.0324 to 0.2060. For the second layer, the Poisson’s ratio ranged from -0.7567 to 0.1683. The values of V_p/V_s ratio less than in the first layer and in some locations in the second layer resulted in negative Poisson’s ratio. The low and negative values of Poisson’s ratio are symptomatic of occurrence of ripable anisotropic materials in the locations where they occur, which suggests that indicated average depth should be removed and refilled with geomaterials that may be resilient to carry engineering loads.

Keywords

Seismic Refraction, Eket, Vp/Vs Ratio, Poisson’s Ratio

Conflicts of Interest

The authors declare no conflicts of interest.

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