Vane cone test of snow

Abstract

To predict vehicle mobility or drawbar pull of a tracked oversnow vehicle on snow covered terrain, the fundamental relations between shear strength, normal stress and deformation were studied experimentally for several types of fresh snow and sintered snow. For this purpose, vane cone (apex angle 30°, height 36.5 mm and 69.9 mm) penetration tests at high penetration rate (3.7 mm/sec) and vane cone shear tests at high shear rate (1.89 mm/sec and 3.49 mm/sec) have been performed in a cold room at constant temperrature -13°C±1°C. Load and torque have been measured automatically for penetration and rotation tests of the vane cones.The results show that the shear deformation properties show some rigid plastic behavior and the relation between shear stress τ and deformation X is given as follows τ = τ0 exp (-2X). And as all vane cone shear tests on snow were test under a normally compressed state, the relation between shear stress τ and normal stress σ satisfied the Coulomb failure criteria as follows τ = C+ σtan ψ (C; cohesive strength, ψ; angle of internal friction). And maximum cone index and vane cone shear strength depend not only on density but also degree of sintering and grain-size distribution of snow particles.The most suitable in-situ test method to predict the drawbar pull property of a tracked oversnow vehicle seems to be to perfom both rectangular plate loading test and vane cone tests simultaneously.