DETECTED OF GYPSUM SOIL LAYER BY USING 2D AND 3D ELECTRICAL RESISTIVITY IMAGING TECHNIQUES IN UNIVERSITY OF ANBAR, IRAQ

Abstract

The 2D electrical resistivity imaging survey was implemented in the area located within the University of Anbar, using a dipole-dipole array to detect the gypsum soil layer. This survey was done along seven analogous 2D lines adjacency in E-W direction, then the data of all 2D lines were merged to produce 3D resistivity imaging models. Laboratory tests of three soil samples in the survey area were analyzed and correlated with data obtained from 2D imaging to determine gypsum content in the soil. Our results of 2D and 3D imaging models show that the gypsum soil layer thickness is 2.53 m approximately, and it is characterized by high differences in the resistivity values in the range of 50 to more than 400 Ωm. This difference is generally caused by high inhomogeneities in the hardness of soil components, while the test results show the gypsum content in the samples equal to 213, 232, and 211 g/kg respectively, and it is indicative of that the soil consists of a high content of gypsum. The correlation between these results is indicative of the area is unstable and can be led to a differential settlement that causes cracks and collapses of the constructions.