ABSTRACT
ABSTRACT: In order to study the effect of two parallel bridges on the same river at small frequency flood, the mathematical model of two parallel bridges on a trapezoidal straight channel has been established with the MIKE21 software. And the super-value of water lever in bridge engineering at small frequency flood has been calculated. Base on the analysis of the associated backwater extent before the pier of every bridge when two bridges has been built at the same time, the results show that: the backwater before the pier of the upstream and downstream bridge both will be affected by the water resistance of other bridge this part of the water level effect relative to its own water blocking effect will been influenced by the water resistance area relativing to its of another bridge and the increases of the proportion coefficient will be decreased with increasing distance relative to the bridge surface width.
