Failure of bridges due to local scour in the vicinity of bridge abutments is a common occurrence. In this study, experiments under two different channel conditions were conducted to assess the impacts of vegetation on...Failure of bridges due to local scour in the vicinity of bridge abutments is a common occurrence. In this study, experiments under two different channel conditions were conducted to assess the impacts of vegetation on channel banks on local scour around a wing-wall abutment with circular edges. Some experiments were conducted in channel with vegetation on channel banks, and other experiments in channel without vegetation on channel bank. The flow velocity and Reynolds stress distributions in scour holes around a wing-wall abutment with circular edges were compared under these 2 different channel conditions. Results reveal that the vegetated-banks can reduce the time for achieving the equilibrium condition from 17 h to 9 h. Also, vegetated-bank channels can result in a significant decrease in the maximum scour depth from 0.084 m（for bare channel bank） to 0.00032 m. Additionally, around the abutment, vegetated-banks play a significant role in diminishing the Reynolds stress（RS） near the bed and removing negative values in RS distribution by weakening unfavorable pressure gradient and down-flow in the upstream of abutment.展开更多
A bi-harmonic potential function was constructed in this study. Love solution was employed to obtain analytical solutions of uniformly loaded plates with two different types of clamped edges. The treatment of clamped ...A bi-harmonic potential function was constructed in this study. Love solution was employed to obtain analytical solutions of uniformly loaded plates with two different types of clamped edges. The treatment of clamped boundary conditions was the same as that adopted by Timoshenko and Goodier (1970). The analytical solution for the first type of clamped boundary condition is identical with that obtained by Luo et al.(2004), and the solutions for both types were compared with the FEM results and the calculations of thin plate theory.展开更多
The transient acoustic field radiated by a piezoelectric thickness-mode transducer into a solid medium is theoretically analysed. It is proved that the field consists of the direct wave, the longitudinal edge waves, t...The transient acoustic field radiated by a piezoelectric thickness-mode transducer into a solid medium is theoretically analysed. It is proved that the field consists of the direct wave, the longitudinal edge waves, the shear edge.waves, the head wave and the surface waves. The wavefront approximations of all these waves are given which result in a clear physical picture which is not only simple but also cotains the main features of the field. The theoretical result well describes the experiment.展开更多
文摘Failure of bridges due to local scour in the vicinity of bridge abutments is a common occurrence. In this study, experiments under two different channel conditions were conducted to assess the impacts of vegetation on channel banks on local scour around a wing-wall abutment with circular edges. Some experiments were conducted in channel with vegetation on channel banks, and other experiments in channel without vegetation on channel bank. The flow velocity and Reynolds stress distributions in scour holes around a wing-wall abutment with circular edges were compared under these 2 different channel conditions. Results reveal that the vegetated-banks can reduce the time for achieving the equilibrium condition from 17 h to 9 h. Also, vegetated-bank channels can result in a significant decrease in the maximum scour depth from 0.084 m（for bare channel bank） to 0.00032 m. Additionally, around the abutment, vegetated-banks play a significant role in diminishing the Reynolds stress（RS） near the bed and removing negative values in RS distribution by weakening unfavorable pressure gradient and down-flow in the upstream of abutment.
文摘A bi-harmonic potential function was constructed in this study. Love solution was employed to obtain analytical solutions of uniformly loaded plates with two different types of clamped edges. The treatment of clamped boundary conditions was the same as that adopted by Timoshenko and Goodier (1970). The analytical solution for the first type of clamped boundary condition is identical with that obtained by Luo et al.(2004), and the solutions for both types were compared with the FEM results and the calculations of thin plate theory.
文摘The transient acoustic field radiated by a piezoelectric thickness-mode transducer into a solid medium is theoretically analysed. It is proved that the field consists of the direct wave, the longitudinal edge waves, the shear edge.waves, the head wave and the surface waves. The wavefront approximations of all these waves are given which result in a clear physical picture which is not only simple but also cotains the main features of the field. The theoretical result well describes the experiment.
