INVESTIGATION OF STABILITY OF ENGINEERING PROJECTS USING SEISMIC REFRACTION TECHNIQUE

Abstract

Seismic refraction survey was conducted at Ibiono Ibom Local government area of Akwa Ibom State, Nigeria, using 12 channels ES 3000S enhancement seismograph. This was done to evaluate and obtained information on depth and thickness of the shallow subsurface and characterized the bearing and engineering parameters on the bases of soil and rock competencies for stability of engineering works. The travel times of refracted waves measured were used to calculate P and S wave velocities employed in the evaluation of bearing strength and engineering parameters. The results revealed that seismic waves penetrated into three layers. The values of depth and thickness for upper layer ranged from 0.0 m to 4.5 m and 4.5 m, middle layer ranged from 5.0 m to 12.5 m and 7.5, lower layer ranged from 15.0 m to 25.2 m and 10.2 m. The bearing capacity parameters calculated were allowable bearing capacity and ultimate bearing capacity, engineering parameters: Concentration Index, Stress Ratio, Material Index and Density Gradient. The third layer reflected good competent soil and rock quality in the southeastern part of the study area, and was delineated as a better layer for engineering stability.

Keywords

• allowable bearing capacity
• ultimate bearing capacity
• engineering parameters
• foundation.