CRREL Permafrost Tunnel

Excavated in perennially frozen silt and gravel adjacent to an area dredged during early placer gold mining, the 360-foot-long tunnel was constructed in several stages during the 1960s. CRREL engineers originally used the tunnel to evaluate methods for underground excavation in frozen soil. The main drift was bored with an Alkirk continuous-cycle miner modified to increase its effectiveness in permafrost.

Today this underground facility, which includes several work chambers, is an active underground laboratory that is available for a variety of research programs. To preserve the permafrost, the tunnel is chilled in the winter by natural convection, with cold air passing in through the entrance and out through a ventilation shaft at the rear of the tunnel. A refrigeration system cools the tunnel portal area in summer to compensate for seasonal warming.

For a virutal tour and more information about the Permafrost Tunnel, please visit the CRREL Permafrost Tunnel homepage.

• Subsurface methods of excavation for mining, transportation and storage cavities.
• Periglacial geomorphology
• Soil physics and chemistry
• Mechanical properties of in-situ frozen soils
• Rate of tunnel closure cause by permafrost creep
• Foundation footing design for structures supported on permafrost
• Excavation techniques for mining placer gold deposits in permafrost