Engineering Geophysical Study for Geotechnical Investigation, Port Sudan, Red Sea, Sudan

Abstract

The overall objective of the study is to locate underground anomalies in form of cavities, fractures, faults or any other anomalies that might exist within the ground subsurface makeup to a depth of 20m below existing ground level using multi-geophysical techniques in term of microgravity and Electrical Resistivity Tomography to meet the requirement of building construction in the project area. Topographically the area is bounded by altitudes as high as 4m in the southern and eastern part and 0m in northern and western and central parts (above the main sea level) towards the east direction. Apparently the terrain surface of the project area is covered by silty and fine-grained sediments of the Sabkha formation. Eight lines of microgravity and Electrical Resistivity Tomography were collected at the proposed site. The interpretation of three lines of gravity data from the proposed site is presented in this work. In each line a small anomalous low value was identified. These may represent week zones in the subsurface. However these anomalous values could also be the result of a local dip in bedrock surface, a variation in the density of bedrock, or a variation in the density of the overburden. Considering the boreholes and ERT sections the formations from top of bed rock to 20m depth in the site are mainly slightly to moderately weathered. The siltstone between 8 and 12m approximately are highly weathered and fractured.