Abstract
Even though extensive pre-grouting is
carried out during the construction of tunnels, certain leakages and drips
remain. These remaining leakages are remedied by a combination of
post-injection and drainage measures with, for example, frost insulated drain
mats, whose function is to prevent the cold tunnel air from reaching a leakage
spot and causing water to freeze. Despite these measures, some water may still
enter the tunnels and cause problems during winter with ice formations and
frost shattering. Icicles, ice pillars and ice-covered roads and railway tracks
require constant maintenance. If ice occurs in the fracture network close to
the tunnel contour or in the interface between the rock and shotcrete, it can
cause degradation of the load-bearing capacity of the tunnel and fall-outs of
both materials. In tunnel sections with water leakage problems it is common to
protect the load-bearing structure from freezing with insulated drainage
systems. To determine where along the tunnel efforts must be made to prevent
ice formation, the temperature conditions of tunnels must be investigated. This
article presents parts of the results from field measurements in two Swedish
railway tunnels. The measurements involves monitoring of air and rock
temperatures, air pressure and air velocity.
Keywords:
Frost penetration, ice formation, frost shattering,
temperature measurement, maintenance, railway tunnel.