Subsurface Investigation Using Electrical Resistivity Imaging for Proposed Industrial Site near Erbil-Kirkuk Borders, Northern Iraq

Osamah Al-Saadi

doi:10.46717/igj.54.2e.14ms-2021-11-30

Abstract

The friendly-environment geophysical methods are commonly used in various engineering and near-surface environmental investigations. Electrical Resistivity Imaging technique was used to investigate the subsurface rocks, sediments properties of a proposed industrial site to characterize the lateral and vertical lithological changes. via the electrical resistivity, to give an overview about the karst, weak and robust subsoil zones. Nineteen 2D ERI profiles using Wenner array with 2 m electrode spacing have been applied to investigate the specific industry area. One of these profiles has been conducted with one-meter electrode spacing. The surveyed profiles are divided into a number of blocks, each block consists of several parallel profiles in a specific direction. The positions of Electrical Resistivity Imaging profiles in the project area have been determined according to a preliminary subject plan from the civil engineers for factory foundation constructions and proposed locations of heavy machines. The inversion results of profiles showed that areas of blocks A, B, C, and D consist mainly of clastic rocks and sediments, e.g., claystone, siltstone and sandstone. The Electrical Resistivity Imaging inversion sections of blocks A, B, C, and D do not show any indication of cavitation or weak zones of sizes more than 2.0 meters, and no signs of gypsum bodies are found in these areas in general. Gypsum bodies are probably detected at block E, the southern part of the study area. The researchers recommended to keep these rocks in block E away from the continuous running water to avoid cavitation. Furthermore, the construction of heavy machines should keep away from this part of the study area to avoid to some extent, subsoil failure and subsidence in the future. Middle and Northern parts are more consistent to the constructions and factory foundations.

Highlights

In the last few decades, electrical resistivity imaging (ERI) or tomography (ERT) has been widely used as a pre-excavation reconnaissance geophysical technique in various near surface environmental and engineering explorations (Reynolds, 2011)
The vast developments of various field techniques have increased the use of these geophysical methods and became indispensable in near-surface prospecting over the time
For the setups of eighteen ERI profiles, two meters electrode-spacing have been employed, which covered about 160 m length in total for each individual surveyed profile, and we investigate about 25 m depth of penetration

Summary

Introduction

In the last few decades, electrical resistivity imaging (ERI) or tomography (ERT) has been widely used as a pre-excavation reconnaissance geophysical technique in various near surface environmental and engineering explorations (Reynolds, 2011). This non-destructive geophysical method (ERI) is helpful in saving time, efforts and costs, for example, the geophysical methods can cover a large area in a reasonable time and with acceptable results (Al-Saadi et al, 2018). Measurement of the subsurface resistivity has been often applied in environmental prospection and numerous survey methods exist.

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