ABSTRACT
The Public Works Authority (PWA) of the State of Qatar, or ASHGHAL, has launched the Wakrah and Wukair Drainage Tunnel, which is a 13km-long and 4.5m-ID sewer tunnel serving Doha’s growing population in the years to come. The depths range from 50 to 60m, which will make the tunnel entirely in the Rus Calcareous (RUS) and Rus Gypsum (RUSGYP) formations, thus this will be the deepest and most challenging TBM tunnelling project in Qatar to date. Little was known about the ground conditions and the specifics of the deep geological formations along the planned alignment at project inception. Therefore, an extensive ground investigation campaign was launched in several phases to confirm the feasibility of the project, as the key to every successful tunnel project is to properly identify and mitigate the risks. The authors will present the findings of the investigations along with the design considerations for weak/soft rock masses commonly found in Doha, Qatar. The authors will also provide an introduction to the specifics of the PWA’s latest project and tunnelling aspects of it.
