A pair of TBM machines designed specifically for the project of urban railway No. 3, section Nhon - Hanoi Station (metro), manufactured by Herrenkecht (Germany), with a length of more than 100m, weighing about 850 tons .
According to the plan, the project will start drilling with the TBM1 "Speed" machine from Station S9 - Kim Ma at a depth of 17.8m. When the TBM1 excavator has drilled about 200m, the TBM2 - "Bold" machine will begin the tunnel drilling process. Completing the launch for the first 240m, the tunnel boring machines will accelerate to a standard speed of about 10m/day to approach the next stations.
Regarding the drilling method, the TBM machine operates in a closed cycle, digging at a maximum speed of 60mm/minute. During the digging process, the machine will spray the cutting head with a soil conditioner, also known as FOAM, to help soften the soil, prevent bunching and help maintain the pressure balance of the digging head.
At the same time, the rear of the machine will spray grease onto the outside surface of the tunnel shell, helping to protect the rear brush part, preventing water from flowing back into the machine and sealing the joints on the outside of the tunnel shell. The rear of the machine also pumps mortar solution to fill the gap between the tunnel lining and the soil to ensure the prevention of subsidence during construction.
After completing the excavation, the robot will install the tunnel lining right behind the rear of the machine with a modern robot arm. The tunnel lining installation time will be about 30 to 35 minutes for a tunnel segment consisting of 6 pieces. The cycle of digging and installing tunnel lining takes place continuously without stopping.
The project uses a TBM machine to drill through the diaphragm wall and through the reinforced soil mass. TBM operates on the principle of earth pressure balance. Behind the shield is a closed partition. Soil from the excavated shield will fall into the closed cavity and create a pressure balance between the excavated soil and unexcavated soil, making the excavated mirror stable and not landslide. The pressure of the soil in the balance chamber is monitored by special devices placed directly in the machine body.
At the bottom of the tunnel, the project has prepared a sliding rail system, which has the role of supporting the TBM and sliding it horizontally from the installation position to the drilling position, supporting the movement of the TBM in narrow spaces.
According to the plan, the total time from the start of drilling for the first TBM until the end of TBM No. 2 is 16 months.
Tunnel drilling construction will be carried out with care and strict supervision to ensure the safety of existing works on the ground and ensure the quality of works under construction.
On the entire route, there are currently 6 buildings that need to be demolished, and 42 buildings that need to be temporarily occupied for 1 month. Hanoi Urban Railway Project Management Board (MRB) has completed the work of paying compensation and temporary housing costs for households who are demolishing the first building to be demolished according to plan. . All households signed a memorandum of agreement and a commitment to hand over the house according to the construction plan.
According to MRB leaders, during the operation of the tunneling robot, there will be sensors to warn about vibration. If the allowed threshold is exceeded, the robot will immediately stop tunneling. Therefore, people can be completely assured because there are solutions to handle scenarios during the tunnel construction process.
