| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1996: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
In this study we made a middle size slope model using plywood boards and carried out a series of experiments on the variations of rock weights, slope gradients, slope length. Impact loads, load-time spectra and speed of falling rocks were measured. Rubbers with two different thicknesses (5 and 10mm) are set up on the surfaces striking the falling rocks and the effect of rubbers is investigated. From these experiments the following results were obtained. The impact loads are found to increase linearly with increasing the falling distances, the slope gradients and the rock weights. The Speed of falling rocks are found to increase linearly with increasing the falling distances, the slope gradients. The speed of falling rocks is constant regardless of the rock weights. Therefore, the energy of rockfall is determined by rock weights in our experiments. The impact loads are decreased about 10%-20% by using rubbers on the surface striking falling rocks. Applying a multiple regression analysis
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to measured impact loads led to a linear relationship with rock weights, falling distances and slope gradients. Among these factors, the slope gradients are the largest in the degree of contribution to the impact loads, followed by the falling distances, then the rock weights. However, the rock weights are not statistically significant, therefore the impact loads are expressed as functions of falling distances and slope gradients. Applying the same analysis to the measured speed of falling-rocks also leads to a linear-relationship with the same factors. In this case, the falling distances are the largest in the degree of contribution to the speed of falling rocks, floowed by the slope gradients, then the rock weights. In the same way as the impact loads, the rock weights are not statistically significant, therefore the speed of falling rocks are expressed as functions of falling distances and slope gradients. Theoretical equation of speed of falling rocks are developed with logarithmic functions. Data of the speed of falling rocks are calculated based on the equation. Applying the multiple regression equation to the calculated data leads to a linear relationship with the falling distances and slope gradients. Less
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