| Summary: | 碩士 === 逢甲大學 === 水利工程與資源保育學系 === 102 === Recently, the extreme climate types occur frequently under the effect of climate change. In addition, the annual rainfall concentrates in the summer in Taiwan. Bed elevations of many rivers in west Taiwan lower down seriously, due to unbalanced sediment transport. It causes the scouring of the river bed around the piers, and results in the exposure of the pier foundation and impacts the safety of bridge.
Therefore, this study develops a new type of protection works, water-permeable ring consolidation works, to enhance the security of bridge foundations. Various parameters including the height of consolidation works and distance between the consolidation works and bridge pier are considered. This study also compares with traditional consolidation works of water-impermeable protection works. Furthermore, the optimal configuration is designed to sawtooth-type ring consolidation works. Based on the experiment, we can understand the scour characteristics and propose optimal allocations of the protection works. It can be served as a reference of design for relevant engineers in the future.
The results show that set the consolidation works in downstream of the piers can uplift the water depth and decrease the energy of flow impacting bridge. The different configurations of consolidation works can reduce the maximum scour depth in front of the piers. When the sawtooth-type ring consolidation works sets at a distance of 1 time to the pier diameter, a height of half time to the pier diameter, a width of saw tooth of 0.8 time to the pier diameter, it is the optimal set type among the experimental conditions conducted in this study. The optimal allocations can reduce 57.3% of the pier scour depth reduction rate and 49.4% of scour holes volume reduction rate of consolidation works downsteam. According to experimental data, we can obtain an experience formula by using multiple regression. The R-squared value of function is 0.877. The scour depth of pier can be predicted by this formula.
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