Stratigraphy and Subsurface Weathering Grade in Determination of Foundation Properties in the Area BetweenPort-Sudan and Suakin, Red Sea Region, NE Sudan
[1]
Omer A. O. Al-Imam, Faculty of Petroleum and Minerals, Al Neelain University, Khartoum, Sudan.
[2]
Khalid A. Elsayed Zeinelabdein, Faculty of Petroleum and Minerals, Al Neelain University, Khartoum, Sudan.
[3]
Abdalla E. M. Elsheikh, Faculty of Petroleum and Minerals, Al Neelain University, Khartoum, Sudan.
The beach and coastal plain of the Red Sea Region of northeastern Sudan have witnessed considerable impact as a result of the growing population. Optimum design and construction of foundation in the coastal plain require detailed surveys of geomorphology and geological conditions combined with geotechnical investigations of soil and marine formations. The study area is about 60 km extends from Port-Sudan to Suakin harbor at the Red Sea coast of Sudan. The coastal plain of the Red Sea is underlain by Tertiary and Mesozoicsediments, overlying unconformably the basement rocks. The raised beach complex consists of marine and continental clastic deposits and reef limestone of Pleistocene and Recent ages overlying the Tertiary formation. The objectives of the current study are to carry out detailed investigation of the subsurface stratigraphy and weathering grade; modeling of the subsurface layering, and to determine the suitable layers for foundation construction. According to facies classification there are two litho logical types: coral reef limestone and alluvial deposits. In Suakin area, the discontinuity of sand, silt and muddy siltstone facies across the area with 3 m throw down on the eastern side of the entrance confirmed the existence of faulting. This area is characterized by complete and high weathering grade facies, where the physical weathering is prevalent. Coral reefs limestone shows the effect of chemical solutions forming channels and cavities. The present study indicates that the area under investigationis characterized by unreliable geotechnical properties; nevertheless, it shows two suitable layers for foundation. According to weathering grade models, the carbonate layers in Green Area and Dama Dama are moderately weathered (III), whereas, all residual and coral limestone in between are highly (IV), and completely weathered (V). High attention should be taken in foundation design and construction in the area and it is strongly recommended to construct piling foundations that reach the bottom layers especially for heavy constructions.
Stratigraphic Facies, Weathering Grade, Red Sea Coast, Sudan
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