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Excavating a subway is a monumental task, involving cutting-edge technology and a specialized team to operate the large underground machines. To better understand this process, Iberê Thenório, from Manual do Mundo, visited the construction site of the new orange line of the São Paulo subway, which will connect Brasilândia, in the northern zone, to the São Joaquim station, close to the city center. During the tour, he showed how the “Tatuzão” advances underground, creating the tunnel that will house the subway line, in addition to the numerous security and support operations that ensure the progress of the work.
The tour begins in a well located near the Pacaembu stadium, where the future FAAP Pacaembu station will be installed. This well will serve as an emergency exit and ventilation, but it is currently the access point for workers and equipment. From the surface to the tunnel, it is necessary to go down by elevator to the level where the subway excavation is taking place. The tunnel structure is 10 meters in diameter and is already partially completed, taking visitors to the Renópolis McKenzie station, where it will connect with the 4-yellow line.
Armadillo in action: technology and precision underground for subway excavation
The “Tatuzão”, technically known as Tunnel Boring Machine (TBM), is the machine responsible for excavating the subway. With an impressive 109 meters long and a height that adapts to the diameter of the tunnel, the Tatuzão works constantly, being a true “factory in motion".
It has 20 professionals on each shift, working 24 hours a day. Inside, there is space for technical support, an infirmary, a cafeteria and even a refuge chamber, with the capacity to shelter 26 people for up to two hours in cases of emergency, such as landslides or fires.
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How the armadillo digs the tunnel
At the front of the machine, a giant drill, similar to a rotary grater, cuts and removes the earth for the subway excavation. This process is aided by a special foam that cools and homogenizes the material, making it easier to remove. This excavated material is then transported out by a conveyor belt.
Control of the advance is meticulous, with the Tatuzão pilot regulating pressure, speed and direction, monitoring what is happening inside and outside the tunnel. For each meter advanced, the structure requires a combination of power and precision.
Wall assembly: Structural reinforcement of the tunnel
To ensure the stability of the tunnel, the Tatuzão installs concrete plates, called staves, which form the reinforcement rings. At each excavated section, the machine fits these plates, which already come with seals. to prevent entry of water.
At the end of each section, a layer of concrete is applied between the tunnel and the plates to fill empty spaces. These segments are manufactured in São Paulo and transported to the construction site, where they are taken underground and positioned as the Tatuzão advances. With the capacity to install around 15 concrete rings per day, construction of the tunnel is proceeding at an intense pace.
Mobility and the advancement of the Tatuzão
The machine doesn’t just move forward on its wheels: it has 50 pistons that extend to push it forward. These pistons also allow the machine to turn, extending further on one side than the other, depending on the desired direction. This sophisticated engineering allows the Armadillo to navigate the challenges of the urban underground with precision, overcoming obstacles and ensuring the structural safety of the tunnel.
Comfort and safety for the team
Working in the subway excavation requires great care for the safety of the operators. Air circulation is ensured by extensive piping that brings fresh air from the surface. In the event of accidents, workers have access to a refuge chamber equipped with supplies and toxic gas filters, which allow them to monitor external conditions and decide on a safe exit from the site.
The subway excavation is one of the most complex phases and challenging aspects of building underground lines. Tatuzão technology, with its various functions and adaptations, is essential to the success of these projects. Each meter excavated and covered represents an advance in public transportation in São Paulo.
