Herrenknecht TBMs Hole Through on Abu Hamour Outfall Project
Two Herrenknecht EPBs have completed their work for the Abu Hamour Outfall Project in Doha, Qatar. The newly created sewage tunnels are important to better protect the city and the inhabitants of Doha from floods after heavy rainfalls.
Both Herrenknecht TBMs each with a diameter of 4.47 m (14.6 ft) only required 12 and 14 months, respectively, for their tunnel sections. Under the guidance of contractor Salini-Impregilo, they achieved remarkable top performances of up to 165 m per week (540 ft). At a depth of around 30 m (100 ft), the EPB method proved to be the optimum choice for the cohesive soil with its high proportion of rock in Doha. Herrenknecht designed a special cutting wheel with a large opening ratio for the customer – resulting in correspondingly efficient material excavation. High maximum push forces ensured top advance rates for both machines. The final breakthrough on July 29 marked the conclusion of Phase 1 of the tunneling work on the project.
“Both EPB shields with segmental lining were perfectly suited for the project requirements in Doha,” said Simone Centis, project manager at Salini-Impregilo, during the breakthrough celebration. “The great partnership with Herrenknecht helped us to find the best technical answers for the often heterogeneous soil. This allowed for highest possible efficiency during tunneling and project progress.”
Qatar is one of the driest places on Earth. When it rains heavily in Doha, this can result in dangerous flooding because the metropolis is only a few meters above sea level, and therefore above the groundwater level. The Abu Hamour Southern Outfall Project should help to reduce this danger in the future. A tunnel system will drain superfluous water and relieve the existing pumps, which lower the high water level. This will save considerable energy and costs for the public. Further projects to improve the drainage situation in Doha and its surroundings are planned or already being constructed, i.e. the Inner Doha Re-sewerage Implementation Strategy (IDRIS) Project.
Herrenknecht technology is also working underground to improve the traffic situation in Qatar’s metropolis. With over 50 km (31 miles) of tunnel already completed for the Doha Metro, 21 EPB Shields from Herrenknecht with a diameter of around 7 m (23 ft) have already completed tunnel drives.