Project 4: STBM – Tunnel Boring Machines (1995-1998)
#ICR 25 years in 25 Projects
25 years ago, we started our journey as ICR participating in two European projects. The first one, was part of the BRITE Project (BRITE BE95-1735) entitled “STBM: Tunnel Boring Machines”. This project was developed between 1995 and 1998 and was dedicated to the analysis of tunnel boring machines.
The STBM project aims to improve safety, provide a better quality and a more cost-effective digging technique for tunnel boring machine. The consortium that was formed for this study consisted of a major contractor (BOUYGUES) that operates many TBMs as an end user and a major European TBM manufacturer (HERRENKNECHT). ALGOSYSTEMS S.A was in charge of supervising the development of the software, while DICESVA and ICR contributed with their experience in noise control and specific acoustic measurements in order to reduce the noise generated by the tunnel boring machine in operation. Two research organizations LRP and IAI provided the necessary theoretical framework.
ICR studied different options and proposals about how to treat the TBM, the external equipment used and how to take into account the noise level received by the tunnel workers, it was decided to define the tunnel as if it was a duct. To treat a duct acoustically, the walls are usually reinforced with absorbent material and silencers are installed.
For practical reasons, treating the tunnel walls with absorbent material was impossible, so it was decided to design a silencer that would reduce the noise caused by the boring car.
Taking the measurements carried out while the Lille metro tunnel was being built together with the measurements made on a model of a tunnel boring machine for the Sydney airport tunnel (from the Herrenknecht company) as well as the realization of a BEM numerical model of the tunnel boring machine, the ideal solution for this project was designed: a silencer wagon. Since the noisy equipment was all located at the head of the TBM, the silencer wagon acted as a silencer inside a duct, preventing the propagation of noise along the tunnel.
This innovative solution would allow a reduction of 30 dBA of the noise produced by the TBM, along with the option of being able to treat external equipment without reducing its accessibility.