Launching a 148m-Long Tunnel Boring Machine from a 15m-Inner Diameter Shaft

Abstract

The city of Doha has grown and expanded rapidly in the last 20 years, but this growth has strained the country's infrastructure, including its aging sewerage system and treatment facilities. ASHGHAL has therefore launched several schemes which involve shallow and deep sewer tunnels and new treatment works to serve Doha's growing population in the years to come. Wakrah and Wukair Drainage Tunnel (WWDT) project scope includes 13.3 km long of bored and lined tunnel using 2 no's 5.85m Diameter Earth Pressure Balance (EPB) TBMs, 8 Shafts, adits with provisions for future connections, ancillary hydraulic structures and Odour Control Facility. Based on WWDT project restrictions the Contractor was required to launch a 148m long Tunnel Boring Machine (TBM) inside a 15m Diameter shaft at a depth of 59.4m. This paper describes how the WWDT project contractor overcame these constraints and successfully launched both TBMs. The TBM launch and commissioning were a contract milestone. The methodology used involved partially mining a stub adit/logistics tunnels using a Sequential Excavation Method (SEM) to accommodate several TBM sections at the bottom of the shaft at the same time several of the TBM gantries were operational on the surface umbilically connected to the cutterhead. This paper will also provide a brief overview of 2 types of TBM launches used recently in Qatar for comparison.