Revealing the first metro tunnel in Saigon

After nearly 5 months of construction, metro tunneling machine No. 1 has completed more than 700m of tunnels, approaching the City Theater station with 30 workers divided into two shifts a day.

TBM robot is a combination of excavators with a total length of 70m and weighing 300 tons, can perform the tunnel construction items by the method of balancing soil pressure.This drill, manufactured in Japan, is worth about 4 million USD, shipped to Ho Chi Minh City and finished assembly in March at a depth of 17 m in the ground, at Ba Son station, District 1.

On May 26, the construction unit conducted TBM drilling package No. 1B 'Building underground section from Ba Son station to City Theater station' , belonging to the project of urban railway No. 1, Ben Thanh route - Suoi Tien.After nearly 5 months of operation, modern robots have drilled more than 700m of the total of 781m long tunnels connecting 2 stations.

Mr. Phan Huu Duy Quoc, Deputy Chief Representative of Shimizu Group in Vietnam, said that on average, construction contractors dig about more than 10 meters a day.The process of drilling to the surface of the precast reinforced concrete bark is transferred to each phase 6 times, each piece is 1.2m long and weighs about 2.5 to 3 tons.

Below the 17m depth of the station Ba Son specialized vehicles moved on the rail to transport the tunnel covers inside after the previous shells were assembled.

Bow-shaped screws to attach two shells are prepared before mounting.Each ton of heavy concrete slabs are prefabricated with hooked screw holes.

The manual crane system will put the shells into the prepared mounting position.

The tunneling engineers and workers said that although construction works by robots, all operations must be careful to ensure safety and smooth operation.

After digging a gap of 1.2m, the lining of the tunnel will in turn be placed by a horizontal crane in place of the existing hydraulic jacks for assembly before continuing drilling.

After being fitted together, the concrete slabs of an enclosed ring and ring are connected together by an arc shaped screw.

Overall the tunneling of concrete slabs is about to staggered together and there are many screws that securely tie them together.Outside when the digging machine has just been grouted, the water does not penetrate inside the shells.

During the excavation process, installing the central control tunnel cover displays the specifications for the engineer to follow.

This 70m-long excavator complex has a modern machinery system, the space inside the tunnel is only wide with the outside diameter of the tunnel of 6.65m, the inner diameter of 6.05m so the devices are designed very neatly.

The nozzle system takes out mud and mud along the length of the tunnel, which is fitted with a transitional pump in the middle section. According to the representative of the contractor, during the digging process, it always ensures absolute tightness, there will be no overflow from outside. Along the tunnel route the contractor places thousands of monitoring points. "Currently the measurement parameters are very positive, the road surface settlement is 2mm, the surrounding buildings have almost no effect. Hopefully the second tunnel has the same positive results," he said. Quoc adds.

During excavation, the soil is transferred to the conveyor and crushed into a liquid mud.This is followed by filtration systems that will extract water for reuse for construction purposes and sandy soil will move away from the site and can be used in construction.

Under the construction site, all communication with the outside can only be done by telephone.With special training and automatic installation, each day there are only 30 engineers and workers working, divided into 2 shifts.

Although machines operate continuously at depths of more than 700m in length, the temperature is always guaranteed to be at the best level for construction.

Large ventilation pipes bring clean air from outside to create a well-ventilated space.The first tunnel has a depth of 10-27m going down to the 4th floor of the City Theater station (the City Theater station is built 4 floors underground), the second tunnel after construction will be shallower and connect to the second floor of this station.

CCTV system is installed in many locations in the tunnel to monitor the construction process, quickly detect troubleshooting if it occurs.

According to the construction unit, the machine has now excavated to Dong Khoi Street, approaching the City Theater.By the end of this October the first tunnel excavation will be completed, then the machine will be removed, brought back to Ba Son station for assembly and preparation for the 2nd tunnel excavation. takes place within 4 months.

Shimizu contractor representative hopes that after the Lunar New Year will start digging new tunnels.The work is currently very urgent but the units are always cautious to ensure safety and schedule.It is expected that by the end of June or the beginning of July 2018, the second tunnel will be completed, the total time for construction of these two tunnels will be about 1 year, including the time of equipment dismantling.

Metro tunnel from City Theater to Ba Son station.