The Piz Nair cableway mountain station, located at an elevation of 3056m asl in eastern Switzerland, is anchored on serpentinite rock on a permafrost rock layer. Due to changing climatic conditions, the frost zone has changed and thus affects the stability of the foundation. The serpentinite rock is heavily eroded, and the eroded area is approximately 5 to 8 m deep. Permafrost degradation with a significant decrease of shear and compressive strength, results in subsidence and horizontal displacements of the foundation. Rock mechanical monitoring systems have been installed to monitor the cause of the damage to the cableway mountain station and to monitor coming foundation improvements.

Huggenberger has provided and collaborated in the installation of a measuring system to monitor the stability of the rock mass, providing instrumentation produced by Sisgeo.

3-D displacement and temperature measurement systems were installed at five 18-meter boreholes. The proposed instruments include for every borehole an inclinometer-settlement system that continuously provides vital information regarding any stabilization measures. SISGEO’s high-precision inclinometer-settlement system was also furnished with 12-point temperature strings. Currently the deformation profiles are measured manually with the portable inclinometer and the magnet extensometer and the temperature strings are recorded automatically with Sisgeo’s OmniaLog data acquisition system.

The implemented monitoring system provides essential information to plan and optimize future rehabilitation work to stabilize the foundation of the cableway summit station. The operator has the possibility and will consider upgrading the platform with Sisgeo’s unique DEX-S system and OmniaLog data acquisition system when the foundation rehabilitation stage begins.