| Snow bridges are installed on roadside slopes as a major measure for preventing avalanches in susceptible areas in Japan. Current methods of designing snow bridges to prevent avalanche must address the problem of shallower snow depth requiring shorter installation intervals in the direction along the line of slopes (i.e.、 the slope distance between bridges)、 making it necessary to install more snow bridges. In this study、 field tests with two slope gradients were performed to examine the snow pressure acting on snow bridges and the glide of snow cover with different slope distances between snow bridges. Theoretical condition for snow fracture near the snow bridge was also examined comparing the design snow pressure with snow compressive strength.[*] The field test results revealed that the snow pressure and glide speed in the case with a long distance between bridges were larger than those in the case with a short distance. In particular、 the measured snow pressure in the case of the longer distance between bridges exceeded the design snow pressure. In the field with shallower slope、 however、 there were no clear differences in the snow pressures regardless of the distances between the bridges. A comparison of the design snow pressures with the theoretical snow compressive strength revealed that the there is a possibility that the distance between bridges can be increased in region with shallower snow depth and low slope angle. |
