On 5 May 2017, CREG’s 3.5m diameter gripper TBM LEA made its first breakthrough of Tunnel Drive 3 on the Greater Beirut Water Supply Project. A celebration was held in presence of representatives from the Council for Development and Reconstruction, CMC di Ravenna (the contractor), the local authorities, CREG and all project partners.

This World Bank financed project - The Greater Beirut Water Supply Project which includes the construction of tunnels extending for approximately 24 kilometers and transfer lines for the water supply of Beirut is contracted by Italian contractor CMC di Ravenna, which was awarded by the Council for Development and Reconstruction, Beirut (Lebanon) in 2014. The scheme is part of the Greater Beirut Water Supply Project to improve the supply of drinkable water in the region. The project is divided into two large parts: tunnels in the hilly area and underground pipelines in the urban area. The tunnels (called Drive 1, 2 3) will be excavated by two Tunnel Boring Machines (TBM). The two gripper TBMs will mine through rock strengths of between 50-170MPa.

In June 2015 CMC di Ravenna signed a contract with CREG (China Railway Engineering Equipment Group Co., Ltd.) for the supply of two gripper type hard rock TBMs. The two 3.5m diameter gripper TBMs are named “LEA” and “YASMINA”.

The TBM LEA was planned to bore Tunnel Drive 3 (4.13km) and then to transferred to bore Tunnel Drive 1 (8.10km) while the TBM YASMINA is planned to bore Tunnel Drive 2 (10.37km). The CREG TBM is designed to manage the local geology – which consists of limestone, dolomitic limestone and dolomitite, which is generally moderately weathered. The cutter heads of the TBMs are equipped with 17-inch back loading disc cutters of Wirth know-how, which ensures cutter head intervention in a safe manner. The TBMs are fitted with a probe drilling system and a grouting system for pre-excavation consolidation grouting. A short cutterhead shield also allows initial support close to the tunnel face. The TBM’s main shield and back-up systems are also tailored to accommodate many complicated systems in the limited space of the TBM.

LEA was launched in August 2016 at Quardaniyeh Outlet Portal. Along Tunnel Drive 3, a lot of faults and high fractured rock were encountered during the tunnelling. With this kind of rock the excavation slows and requires the use of supports like mesh and ring beams in order to avoid any risk such as rock falling. The maximum inclination of 4.97% for Tunnel Drive 3 alignment is designed in order to pass under an existing valley. It is a big challenge for an open gripper TBM specially when dealing with de-watering works. Despite those difficulties, especially the type of dangerous rock encountered, TBM LEA’s average overall rate since the launching of the TBM is 18m/day, whereas the maximum record on daily rate was noted at 48.22 m/day and on April 2017 the monthly rate was noted at 894.8 m/month and up to 98.63% machine availability. These impressive records shall be attributed to the machine itself and the joint efforts and close cooperation between the teams of CMC di Ravenna and CREG.

The second set of TBM YASMINA was launched on 11 September 2016, YASMINA has successfully driven through the tunnel section with minimum radius curves of 300m in the initial stage, and it has driven over 4.5km in sound conditions.

The performance of the TBMs was highly commended at the breakthrough ceremony by Mr. Paolo Mauri, Area Manager of Middle East of CMC di Ravenna. “We reach a good record. We reached more than 48 meter for daily rate, which was more than expected as a result. So I think it's definitely a good machine and a good assistance from CREG. It's the CREG's assistance and CREG's engineers, which is a big added value. And this makes the results.”

Established in 1901, CMC di Ravenna, is a leading Italian construction company, and has been operating in International markets for more than 40 years. Its business scope covers the transportation, hydraulic and irrigation, constructions, ecological and environmental sectros, as well as in port and maritime works.

The Greater Beruit Water Supply project is scheduled to go into operation in 2019 to supply drinkable water for 1.6 million people in the region.

Machine Specification

Total thrust 8,972kN
Maximum torque 1,800kNm (breakout torque)
Cutterhead drive Electric, variable speed
Cutterhead power 1,200kW
Cutterhead rotation 0-8.5-14.5 rpm
No. of cutters 26
TBM length 240m
TBM conveyor L=19m
Backup conveyor L=130m
Transformer Capacity: 2600kV

Click here for video on TBM LEA's breakthrough