Fracture toughness of snow in shear under friction

The fracture toughness of snow in shear is one of the most relevant parameters when studying the mechanics of snow slab avalanche release. Double-cantilever snow beams were loaded asymmetrically to determine $K_{\mathrm{IIc}}.$ If crack surfaces touch under applied pressure, the fracture toughness in shear of snow $(\rho =247\mathrm{}\hspace{0.5em}{\mathrm{kg}\mathrm{}\mathrm{m}}^{-3})$ is $K_{\mathrm{IIc}}=680\mathrm{}\pm 60\hspace{0.5em}{\mathrm{Pa}\mathrm{}\mathrm{m}}^{1/2}.$ Screening of the stress intensity at the crack tip occurs by Newtonian friction with $k=1.3\mathrm{}\pm 0.47$ along the crack faces.