TITLE:
Poisson’s Ratio of Surface Soils and Shallow Sediments Determined from Seismic Compressional and Shear Wave Velocities
AUTHORS:
U. E. Essien, A. O. Akankpo, M. U. Igboekwe
KEYWORDS:
Seismic Refraction, Eket, Vp/Vs Ratio, Poisson’s Ratio
JOURNAL NAME:
International Journal of Geosciences,
Vol.5 No.12,
November
27,
2014
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, Vp/Vs ratio
ranged from 1.0289 to 1.4185 for the top layer. Vp/Vs 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 Vp/Vs 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.