Installing Rockdelta resilient mats vibration attenuation of 20 dB was achieved in the mean frequency between 63 and 125 Hz. In the main part of the tunnel mats with a thickness of 50 mm were installed at the base of the rail track superstructure. In the section underneath the church mats with a thickness of 85 mm were applied. The implementation of the Rockdelta mats resulted in effective protection of the historic church from structural damage by ground borne vibration. The comfort of passengers and personnel is guaranteed as well as that of the people in the buildings above the tunnel.
The Rockdelta solution brought with it several advantages for this project. The 60.000 m2 of natural stone wool mats that were used are made from fire-safe, non-flammable stone wool.
Fire-safety was a major issue, especially in view of the use of dynamite to blast the tunnel. Sometimes the rubber elements with which the tunnel is protected near the blasting area catch fire and may cause tunnel fires. The non-flammable Rockdelta mats were safe to store and use inside the tunnel at any moment.
Ease of installation
The Rockdelta mats are very easy to handle and easy to install, no special tools are needed, and no welding, gluing or taping is required. This proved a big advantage in the confined tunnel space and sometimes difficult working conditions. Thanks to this ease of installation, the use of Rockdelta was never cause of delays and put no additional pressure on the tight schedule.
Rockdelta resilient mats can be installed on an uneven surface without the risk of the material being punctured by stones or sharp edges. Therefore, the granite bottom did not have to be flattened completely, saving much time and money.
Robust Product-Weather proof
The stone wool mats are insensitive to weather conditions. During storage and installing sub-zero or high ambient temperatures and moisture do not influence the intrinsic properties or the processability of the mats.
Once installed and covered with ballast stones the mats were required to be able to bear the load of trucks and lorries for internal logistics. Rockdelta met this requirement easily as the mats can bear up to 20 tons per m2.
Rockdelta mats are maintenance free and their tested and certified life expectancy of more than 50 years amply exceeds the 40 years required for this project.