Estimations and Experiments of Spur Dyke Head Scour Depth

• Main Authors: Po-Wei Lin, 林柏瑋
• Other Authors: Hsun-Chuan Chan
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/43834635126189813626

碩士 === 國立中興大學 === 水土保持學系所 === 104 === This study presents a semi-empirical model to estimate the temporal evolution of scour at a spur dike in clear-water scour conditions. The time variation of the scour hole related to local vortex system in front of the dike was used to predict the scour depth. A sediment transport factor was introduced to account the rate of sediment transport around the spur dike. In the initial stage of scour, the transformation of the scour hole form the shape of an inversed cone to an one-half horseshoe was approximated by a form correction factor. An experimental program was carried out to estimate the parameters involved in the model (flow intensities equal to 0.755, 0.820, 0.829, and 0.893) and evaluate the accuracy of the model (flow intensities equal to 0.794 and 0.874). The maximum scour depth at the spur dike was calculated by the present model and the basis was discussed. It was showed that the form correction factor is proportional to the volume of scour hole in a linear relationship with a determinant coefficient of 0.84. The sediment transport factor was found to be determined by the flow rates with a quadratic function of determinant coefficient equal to 0.99. Comparisons of the predicted and measured scour depth showed the averaged errors were equal to 2.99% and 1.90% for the experiments of flow intensities equal to 0.794 and 0.874 respectively. The errors were lower the standard of the averaged errors of 25% proposed by the previous researcher in the cases of predicting dike scour. The estimated temporal evolution of scour depth satisfactory agrees with the experimental data.