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| Research on the mechanism of impulse wave generated by the collapse of granular column |
| HUANG Bolin，WANG Jian |
| (Hubei Key Laboratory of Disaster Prevention and Mitigation，China Three Gorges University，Yichang，Hubei 443002，China) |
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Abstract There are usually columnar dangerous rock masses in the cliff coastline near the bank，which will generate catastrophic impulse wave when it fails with disintegration and plunges into the water. In this study，11 groups of physical experiments were carried out on the basis of PIV technology. For the first time，the coupled motion vector process of avalanche particles and water body was shown. The data and pictures of the tests were analyzed by the methods of phenomenon analysis，theoretical formula verification and data regression. The test results showed that the pushment of particles at the bottom was the main way to cause the water body to form wave upward and outward. The higher the column was，the bigger maximum impulse wave was. The time of the generation of maximum impulse wave was earlier than the time of the stop of the collapse. The final potential energy loss rate of granular column was about 37%–75%. There were two types of waves generated by the collapse of the granular column，i.e. the translation wave and the transition wave，among which the solitary wave form was in good agreement with KdV?s theoretical solution：the average deviation error was only 5.4%. There existed a “saturation” phenomenon for the maximum amplitude of impulse wave. The critical shape coefficient a was 5，that is to say，the amplitude of wave generated was basically kept unchanged when a ≥ 5. Therefore，the step prediction functions of the maximum amplitude were discussed by nonlinear regression，the percentage of difference between predicted value and experimental value was about 0.03%–6.7%. These functions are more suitable for the prediction of the impulse wave generated by the buckling collapse of the granular column. This study can provide technical support for the hazard prevention and mitigation of columnar dangerous rock mass in reservoir area or coastline.
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2020, Vol. 39 
