An Integrated Microgravity and Soil Analysis Methods to Assist the Resistivity Profiles Interpretation in an Engineering Site Southern Baghdad, Iraq

Abstract

A 2D Electrical Resistivity Imaging survey was conducted at the Al-Jadiriya Campus of Baghdad University. The 2D resistivity survey was achieved on two profiles using the Wenner- Schlumberger configuration. The length of each profile is 80 meters, and the spacing between adjacent electrodes is 1 mr. The obtained resistivity data were interpreted using the RES2DINV program. Both profiles show high resistivity anomaly at depths more than 6 meters, extending from a distance of 32-44 m and 37-44 mrs for profiles 1 and 2, respectively. In addition to the deep anomalies, there are many shallow high-resistivity anomalies. A microgravity survey was carried out for a distance of 20- 60 m along the two profiles to check the nature of the deep high resistivity anomaly. The gravity profiles showed many positive gravity anomalies reflected the effect of shallow sources, which coincide with the shallow relatively high resistivity anomalies. Many soil samples were analyzed chemically and sedimentologically to investigate soil homogeneity. It is found that the soil is homogenous, composed mainly of silt and clay. According to the integrated interpretation of resistivity, gravity, and soil analyses, it is found that the high resistivity anomaly is related to dry compacted soil mass, which is indicated in the gravity study. This study confirms the importance of integrated research to access better geophysical interpretation. The water table level in the study sites ranges 5.6–6.2 ms.