Rectangular plate loading test on snow

Abstract

To predict vehicle mobility or drawbar pull of tracked oversnow vehicle on snow covered terrain, the fundamental relation between the structural properties of snow and deformation energy of snow due to compression were studied experimentally. For this purpose, rectangular plate (7.6 cm × 7.6 cm) loading tests at high deformation rate (3.7mm/sec) were carried out for several types of fresh snow and sintered snow in a cold room at constant temperature -13°C ± 1°C. This new apparatus for rectangular plats loading tests is designed as a strain controlled system, and also for penetration and rotation test of vane cones.The relation between penetration resistance and depth of penetration of a rectangular plate show elastoplastic behaviour and a saw-toothed effect due to the microfracture of snow until the density of snow reaches the threshold density. As a result, it is shown that the deformation energy due to compression of snow decreases with the increase of the coefficient of propagation of plastic compression. For fresh snow having an initial density of 0.18 to 0.42g/cm3, the elastic modulus increases from 6 × 10-3 to 7.8 × 10-2kg/cm2 · cm and the coefficient of propagation of plastic compression decreases from 5.8 to 3.0, with the increase of initial density. For sintered snow having an initial density of 0.40g/cm3, the initial density does not vary but the elastic modulus increases from 1.00 to 3.10 kg/cm2 · cm and the coefficient of propagation of plastic compression decreases from 3.2 to 2.1, with the increase of age of sintered snow.Thus the relations between coefficient of propagation of plastic compression and deformation energy due to settlement of an oversnow vehicle have been analysed for several types of fresh and sintered snow.