Chapter 4: Local ground movements and effects on infrastructures

• Main Authors: M. Dall’Amico, A. Carton, E. Cremonese, M. Curtaz, U. Morra di Cella, L. Paro, M. Phillips, P. Pogliotti, P. Schoeneich, G. Zampedri, M. Zumiani, SEPPI, ROBERTO
• Other Authors: P. Schoeneich, M. Dall’Amico. P. Deline, A. Zischg, M., Dall’Amico, A., Carton, E., Cremonese, M., Curtaz, U., Morra di Cella, L., Paro, M., Phillip, P., Pogliotti, P., Schoeneich, Seppi, Roberto, G., Zampedri, M., Zumiani
• Format: Book Part
• Language: English
• Published: ADRA - Association pour la diffusion de la recherche alpine 2011
• Subjects: Ice; permafrost; Thermokarst
• Online Access: http://hdl.handle.net/11571/379294; http://www.permanet-alpinespace.eu/archive/pdf/WP6_2_local_ground_movements.pdf

Local ground movements may be defined as phenomena of instability that affect slopes or flat ground in a surface of hundreds to thousands of square meters. Local ground movements are a common feature in permafrost areas, and include: •Horizontal downslope movements, due to the creep of permafrost bodies. •Vertical settling movements, due to the melting of ice bodies and/or interstitial ice. These movements may cause damages to buildings and infrastructures or more rarely represent a hazard for persons: •Damages to buildings are mainly due to differential settling of the ground. Some mountain huts are endangered by the collapse of the rock foundations. •Cableways are the most common and sensible infrastructures in alpine permafrost areas. Movements of pylons and of start and end stations lead to problems of cable alignement. It induces increased maintenance costs, and reduces the lifetime of the investment. •The stability of hazard protection infrastructures can be changelled by permafrost degradation. •Thermokarst phenomena due to the removal or compaction of the surface layer can cause substantial damage to planation works like ski tracks or roads. In many cases, it must be emphasized that the infrastructure may induce itself the degradation of the undelying permafrost, through heat conduction by the infrastructure, or through the modification of the insulation capacity of the ground. An adapted conception of the infrastructure can, in many cases, avoid both the influence on the permafrost state and damages due to movements. When planning an infrastructure in a high mountain environement (e.g. above 2400 m), the possible presence of permafrost should always be investigated prior to the conception. The permafrost distribution map can give a first indication. Geophysical methods permit to detect the possible occurrence of frozen ground. But only a drilling can give reliable information on the presence and thickness of ground ice. Monitoring of temperature and movements during at least one year will give ...