The Dubai Metro is a urban transit rail system operating in Dubai, United Arab Emirates. Two lines are currently operational, the Red Line and Green Line. Additional lines are also planned for coming years.

For the construction of the Red Line, Dextra has been involved between 2005 and 2010 together with the contractors making J T Metro (Obayashi Corporation – Kajima – YapiMerkezi) for the supply of numerous Dextra solutions for various packages and stations.

For the station construction, especially for the foundation works (piles and perimeter d-walls), Dextra supplied its Bartec rebar splicing solutions. Rebar couplers were used for vertical connections in piles D-Walls, columns and piers. Rebar couplers were also used for reconnecting slabs onto the D-Walls. A total of 800,000 Bartec rebar couplers have been supplied for this project, supported by several Bartec equipment sets maintained by local Dextra Aftersales team.

For minor repair applications, RepairGrip couplers were also supplied to splice rebar which had not be prepared with a thread and which had unsufficient produding length to be spliced.

For foundation works as well. Dextra supplied more than 60km of Sonitec sonic tubes, used the CSL integrity testing of piles and walls. Sonitec can be easily assembled at site thanks to their push-fit mouth system, boosting teams productivity and avoiding the tedious task of welding tubes together.

Finally, to accelerate tunneling breakthrough phases and minimize TBMs (tunnel boring machines) time when exiting/entering shafts and stations, Dextra engineered the design of GFRP Soft Eyes and supplied more than 400 km of composite rebar for numerous station packages.

Coimbra B-Portagem Mondego Metro project is part of the mass transit public transport system of Coimbra, Portugal. Dextra has played a significant role by providing Sonitec tubes for pile testing.

Dextra has supplied Sonitec tubes for testing a total of 67 piles ranging from 12 to 19 meters in depth. The tubes have been instrumental in conducting these tests with the Cross-Hole Sonic Logging (CSL) methodology.

The innovative push-fit connection system of Sonitec has greatly reduced labor time during installation. Thanks to this user-friendly system, the contractor has experienced smoother and more efficient pile testing processes. By eliminating the need for additional labor-intensive procedures, the contractor has saved valuable time and resources. It also ensures a secure and reliable connection between piles.

London Crossrail (given the name Elizabeth line in 2016) is the largest engineering project in Europe. It is a major part of Transport for London’s investment programme and the largest addition to the transport system for 50 years.

The project consists in a 118-km east-west rail link across Greater London which will run from Reading and Heathrow in the west to Shenfield and Abbey Wood in the east.

Since 2009, Dextra has delivered more than 600,000 Griptec connections on more than 20 packages including stations such as :

• Liverpool Street
• Paddington
• Bond Street
• Canary Wharf
• Royal Oak portal
• Pudding Mill Lane

Griptec couplers have been used on D-Wall (vertical and horizontal connections), columns and piles (vertical connections).

Segments of Crossrail are expected to start operating progressively, with full completion scheduled for December 2019.

The Rio de Janeiro Line 4 is a subway line. It is part elevated and part underground (2 segments). The line has been planned to open for the 2016 Rio de Janeiro Summer Olympics.

Dextra has been involved since between 2013 and 2015 in the design, engineering and supply of four large FRP Soft Eyes for the station entry/exit points. Those Soft-Eyes were the first ever delivered in the South American continent.

Prior to D-Wall construction, Dextra engineers the FRP cage design taking into account size of the TBM, margin for error, soil forces and more design parameters.

Thanks to the properties of FRP material, Tunnel Boring Machines cut through the D-Wall in a minimum time, saving time on schedule and ensuring the perfect condition of the TBM’s head. The time factor is especially important in humid environments such as Rio to limit the water entry into the station excavations.

On this project, Dextra also supplied Rolltec Rebar Couplers, used as vertical connections in the station diaphragm walls as vertical connectors to reconnect cages.

Couplers were also used horizontally to provide a reconnection point for slabs (at station level and at the surface) in the D-Walls.

Nagpur, the second capital of Maharashtra and one of the fastest developing city in India is witnessing major growth in terms of Infrastructure. The development encompasses primarily the connectivity, of which Metro rail becomes a major part.

Incepted in 2016, the metro project is being a subject of acclaimed discussion for its speed of execution and the quality of construction.

Within the city boundaries, it requires the highest standards of safety considerations including the seismic analysis of structure in service life.

Project Requirement

The fast track project has typical structure for its Line 1 alignment, where the viaducts are supporting 2 levels of pathways, lower one for NH-7 and upper one for the metro rail. As the impact loading is a big concern due to train movement.
Being the stretch of always busy traffic, a solution was required which does not have to revise the existing design. Plus a major concern was the impact on speed of the otherwise fast moving project. The issue was concerning to all the stakeholders especially the GC for the project, who were looking to maintain the agility as well as find a sustainable solution.

Solution

Dextra Introduced Shear Key Bars for the priority section allowing the structure to neutralize the seismic forces. This not only helped the contractor to get the work done faster, but also enabled the client to go for the trial run earlier than expected.

The Doha Metro is a rapid transportation system, designed as an integral component to the larger Qatar rail network. This country wide mega-scale infrastructural project consists of 300km of rail and 100 stations. The rail network to reduce traffic congestion, and to connect the people of Qatar with the rest of the GCC region. At the city scale, currently under construction, the metro is projected to be operational by the end of 2019. It will serve Doha and its surrounding suburbs with stations located in all major nodes of the metropolis. Doha Metro will be operating both at grade and below grade, with the majority of the metro project being underground. Complex tunneling and soil retaining solutions by Dextra were utilized in the construction of this project.

Glass Fiber Reinforced Polymers (GFRP) as Tie-back anchors to retain soil

To eliminate concerns of encroachment, and obstacle for future construction projects, the Diaphragm Wall (D-Wall) at Al Sadd C-Ring Station were post-tensioned anchored with ASTEC Active Active Anchor. These high performance, fully cut-able GFRP anchors were chosen by ALSYJ JV contractors and the D-Wall anchors of choice. This innovative solution was chosen because it can be cut by Tunnel Boring Machines (TBM) or standard excavation equipment, it also doesn’t need to be removed from the ground even in temporary applications. For Al Sadd C-Ring Station 7,113 strands for GFRP rebars were used to make approximately 700 ground retaining anchors used in the D-WALL around that station.

The Second Ho Chi Minh City Environmental Sanitation Project consists of the construction of interceptor that will convey the wastewater collected from the Nhiêu Lộc-Thị Nghè Canal and District 2 areas of Ho Chi Minh City to the treatment plant.

Dextra has been involved in the construction of the large underground system by supplying 40 Soft-Eyes to assist in the tunnel breakthroughs.

The cuttable Glass Fiber Reinforced Polymer (GFRP) Soft-Eyes were applied to reinforce 21 shafts, allowing the penetration by the Tunnel Boring Machine (TBM) without the need of removing steel reinforcement and without the risk to damage the TBM’s head.

With its completion, planned to be in 2022, the wastewater services in HCMC will have a considerably more sustainable nature, and will be remembered as the first big step toward the alleviation of the environmental and sanitation issues of the Country.