Gotthard base tunnel │Sedrun sub-section

PROJECT

CLIENT	ALPTRANSIT GOTTHARD AG
LOCATION	SEDRUN (GR)
DURATION	1991 - 2011

Geological construction support services

The New Railway Link through the Alps - NRLA (Sedrun sub-section) includes two single-track tunnel tubes, a multifunction station with side galleries, longitudinal and transverse caverns, as well as a ventilation gallery.

HIGHLIGHTS

Excavation in the extremely tectonically fractured rock mass of the Tavetsch Intermediate Massif, with low stability, plastic deformation and high anisotropy of the rock’s mechanical properties.
Passing through areas with a potentially very high water content and fault zones in the Urseren Garvera Zone and the Gotthard Massif in the inflow area of the Nalps, Curnera and Santa Maria dams.
Systematic preliminary explorations in both single-track tunnel tubes, totalling 8,420 metres. Core drillings (30 – 360 metres long) and 13,150 metres percussion drillings (20 – 120 metres long).

OUR SERVICES

1991-1992: Detailed geological mappings for forecasting the Sedrun sub-section.
1995 -1998: Preliminary geological investigations during the design phase (support for and assessment of deep soundings).
Spring 2003 - 2011: Geological construction support services as a geologist group along with SCH AG, Chur.
Geological survey and construction support services during the excavation of the multifunction station and the main tunnel tubes.
Support for injection sealing of flows of water in the area of the Nalps dam.
Survey and support for preventer-protected horizontal percussion and core drillings.
Monitoring of the hydrological conditions in the inflow area of the potentially threatened dam installations.
Evaluation of reuse of excavation materials for processing as concrete aggregate.
Drafting of the final documentation for the structure.