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other areas, eventually 
with less intensity. The spatial development of 
the phenomenon should be further studied. 
2.5 Final results 
Despite the significant settlements observed 
during the construction of the tunnels, with 
values up to 50 mm, the buildings nearby the 
excavation site didn’t suffer any major damage. 
In fact, the settlements measured on the single 
buildings were almost even and no significant 
differential settlement was observed. 
The only damages to the buildings that was 
recorded pertained to the limited opening of 
already existing fissures. The dimensions 
reached by the fissures did not represent any 
danger and could be easily repaired. 
The tunnel excavation was completed within 
the time schedule and the estimated costs. 
3 CONCLUSION 
The experience gained during the excavation of 
the Vedeggio-Cassarate tunnel in southern 
Switzerland has shown that complex geological 
and hydro-geological conditions can lead to 
unexpected ground behaviour during and after 
underground excavation works. 
The present case has shown that ground 
layers carrying artesian groundwater with 
relatively high pressures, confined by other 
extremely watertight ground layers, could result 
in extremely sensitive behaviour following any 
minor change in the pressure of the 
groundwater. 
With regards to the drainage of the artesian 
groundwater (independently from the amount of 
water drained), the ground behaviour may show 
an immediate start and a strong increase of the 
ground settlements followed by a partial 
recovery of the measured surface settlements 
after restoring the initial pressure of the artesian 
groundwater following the completion of the 
underground works. 
When work is to be carried out in similar 
geological and hydro-geological conditions, the 
risks which could be related to such ground 
behaviour should be taken into account at the 
design stage of the work. 
ACKNOWLEDGEMENTS 
Department of Construction of the Canton of 
Tessin, Switzerland. 
REFERENCES 
Como G., Ferrari A., Sidler M. 2008. Lockergesteins-
strecke des Vedeggio – Cassarate Tunnels: Bauhilfs-
massnhamen im Mittelpunkt des Bauvorhabens, In: 
Bauhilfsmassnahmen im Tunnelbau, Intervention at 
the annual colloquium of the geotechnical Institute 
(IGT) of the Swiss Federal Institute of Technology 
(ETHZ). Zurich. 
G. Como, Ferrari A., Gubler G. 25.04.2008. Tunnel 
Vedeggio – Cassarate: Tunnelvortrieb in wasser-
gesättigtem Lockergestein. In: Seminar of the Swiss 
Society for Soil and Rock Mechanics SGBF. Lugano