| We report the parameters that affect the healing of Columbic (C) faulted (or analogue) S2 columnar ice and the effect that healing has on the resistance to frictional sliding. Healing is defined as the restoration of mechanical strength to an interface in ice during periods of dormancy when the driving forces for sliding along the interface falls below the level required for continuous sliding.;Damaged laboratory grown polycrystalline specimens of ice, freshwater and saline, were tested under a variety of conditions (biaxial confining stresses (60kPa to 750 kPa), biaxial confinement times (3s to 18 hours), temperatures (-3°C to -30°C), three surface roughnesses) to explore the effect of these parameters on healing. The damage was imparted as a C-fault created under low confinement or as a fault made using a bandsaw cut (termed saw-cut fault) or as a smoothed bandsaw cut (termed smooth fault). Healing was quantified through the uniaxial fracture strength, as defined by the maximum force before failure divided by the area over which that force was applied.;The uniaxial fracture strengths show that the degree of healing is dependent upon time, temperature, confinement, and salinity but not dependent on roughness. The greater the degree of healing, the more the ice behaves like virgin material in that the failure strength approaches that for undamaged ice and the failure plane becomes less dependent on the pre-existing fault.;Biaxial confinement experiments allowed for healing to be quantified by the resistance to sliding, i.e. as a friction coefficient. These experiments illustrate that the friction coefficient is dependent on both the magnitude of the healing force and the length of time the specimen is held under biaxial confinement.;We show that the underlying mechanism involved in healing is pressure sintering caused by the creep of connecting asperities. |
