Investigation for Stability of Rock for Foundation and Depth to Aquifer Determination Using Vertical Electrical Sounding at Ekwereonu Close 33 Nkwelle Ezunaka, Southeastern Nigeria

Abstract

In today’s world, field investigation is a necessity to get a detailed overview of any area for civil engineering construction purpose. Precise determination of engineering geological properties is essential to plan for a proper design and successful construction for any civil engineering structure. The traditionally practiced conventional methods for the same are invasive, costly and time consuming. Electrical Resistivity Survey is an attractive tool for delineating subsurface geology without soil disturbance. The investigation involved the use of vertical electrical sounding of schlumberger array. The location is within Ogwashi Formation with latitudes 6°11.155’N to 6°11.171’N and longitudes 6° 48.868’E to 6° 48.883’E with elevation varying between 68m and 79m.The interpretation revealed resistivity range of 396 Ohmm to 746Ohmm from depth of 0.934m to 2.2m for the foundation of structures, while the resistivity and depth to aquifer of the location is 1569Ohmm at
9.44m and 1314Ohmm at 168m for the second zone.. In between these lithologies are mainly clay/shale units. This suggest that the underlying materials has to be treated or soil stabilized with one of the options of recommendation. This will enhance the bearing capacity of the foundation soil. Deep foundation is recommended for the main load bearing foundation to ensure that the load is mounted by the civil structure is transmitted to the hard shale. Failure to follow these procedures could lead to structural failure and economic loss or wastage.