________________ Excellent tunnelling performances can be achieved in stable rock with gripper machines. One crucial factor is the time required for the necessary rock support measures. By integrating the so-called L1* work area, more space was created just behind the cutterhead of the gripper machine, thus making it possible to install the steel support directly after the drilling process.
Swift rock support measures, high tunnelling performance.
An essential factor in how Gripper TBMs function in hard rock work is the optimum interplay between drilling, bracing, support and safety systems. The time required for safety measures following the drilling process is of utmost importance for the entire tunnelling performance. Thus, how the so-called L1* work area between the gripper shield and the gripper plates is fitted out as a safety area is of great significance. This is where the ring erectors, anchor drilling devices and the wire-mesh erectors necessary for the steel support installation are stored. The great advantage is that the steel support can be provided rapidly, since the L1* workspace is located just behind the cutter head, meaning that the support measures can already take place right after the drilling process.
Apart from the steel arch lining and mesh-steel lining, the shotcrete is the most important safety measure for supporting the rock where the gripper process is used. The shotcrete is applied in a dry or wet process and the use of additives makes it possible to adjust its properties in terms of its initial hardening, adhesion and setting behavior. This means that the lining can be installed in immediate proximity to the supporting devices with maximum adhesion to the rock. The shotcrete is extremely versatile and can easily be adapted to meet changing requirements, even for partial excavations of any size.
Through permanent optimization processes and further development at Herrenknecht, mechanized work processes have been extensively automated. As such, the innovative technology increases the tunnelling performance while at the same time enhancing safety for the machine personnel.