Study on the Characteristics of Flow and Force on a Bridge Desk

• Main Authors: Ying-Chi Chen, 陳盈圻
• Other Authors: 蔡清標
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/05263374759331313275

碩士 === 國立中興大學 === 土木工程學系所 === 100 === During August 06 ~ 09, 2009, Typhoon Morakot brought breaking records of rainfall. River surge and dam break flow by Dammed Lake occurred along both banks of most wild creels of three tributaries in Gaopin River basin. Many serious disasters of landslips, bridge desk damages occurred in Gaopin River basin. Therefore, in this study, a numerical simulation was investigate the flow variation, impact force, and uplift force by field and dam break flow passing through bridge desk. The three-dimension RANS with RNG turbulent model associated with volume of fluid (VOF) method was applied for the numerical simulation. The numerical results were first verified with the previous experiment data and the simulation. 　　The simulation results show that increasing volume rate of subcritical flow will lead the flow to partially inundation over the bridge desk, and the impact force will increase. The uplift force values are negative, and the negative value will increase as the Froude number increases except the flow field of separation point. As for the water level of dam break flow, it leads the flow field of totally inundation over the bridge desk. At the moment of the dam break flow impact bridge desk, it will occur that the impact force maximum and uplift force maximum acting on the desk. During Typhoon Morakot, it caused JiaXian Township was buried by many bridges severely damaged. It occurred while for the dam break flow by landslide-dammed Lake failure next day, not for the duration of the highest water level. Due to the bridge desk couldn''t afford the impact force maximum and uplift force maximum, it damaged before steady.