Seismic shear-wave imaging in front of Tunnel-Boring Machines

When a tunnel is bored in soft soil using Tunnel-Boring Machines, the machine bores nearly always “blindly”, i.e., no system is then available to sense the ground in front of the TBM. For soft soils, shear-wave seismic is often more suitable than P-wave seismic. The expertise in the group on shear waves in soft soils is being used to develop a shear-wave system for imaging in front of a TBM as part of an EU-sponsored project, called NeTTUN (www.nettun.org). The main challenge is to do such imaging using the limited space for the seismic sensing system and obtain ground images in front of the TBM that can reduce the risk of tunnel boring.