冲刷作用下桥墩结构体系的屈曲荷载计算

Bent buckling evaluation of bridge pier system under scour effect

为分析冲刷对桥墩结构体系承载力的影响,在土-桩-桥墩结构相互作用的基础上提出桥墩-群桩的等效结构体系,考虑了滑动橡胶支座和承台作用,推导桥墩结构体系的屈曲荷载计算公式.以苏通大桥的辅助桥墩为例,分析了冲刷深度、桩墩刚度比、桥墩高度、承台重量和滑动橡胶支座对屈曲荷载的影响.结果表明,当冲刷深度从0m增加到90m时,屈曲荷载降低了69.3%.桩墩刚度比、桥墩长度和橡胶支座等对群桩-桥墩结构体系的稳定有较重要的影响,承台重量对结构体系的静力稳定影响较小.在实际工程中,可优化桥墩和群桩的刚度比、长度比,使得结构体系拥有合理的刚度分布,从而在冲刷作用下可在一定程度上减缓桥墩-群桩结构体系的屈曲性能的降低.在桥墩结构体系的屈曲荷载计算中,应考虑滑动橡胶支座刚度的影响.

In order to study bridge scour safety evaluation, the equivalent structural system has been raised for the bridge pier system on the basis of interaction between soil, pile and bridge pier. The effect of rub- ber hearing and cap are considered; and the buckling capacities is put forward. Taking the Sutong bridge for examole, the influences of scour depth, stiffness ratio of pile to pier length, cap＇ weight and rubber hearing＇s stiffness on buckling load are also analyzed to evaluate the effects on the relationship between scour depth and buckling capacities. The results show that as the scour depth increases from 0 m to 90 m, the buckling load in the Sutong bridge decreases by 69. 3%. The stiffness distribution, pier length and rubber bearing＇s stiffness are very important to the buckling capacities of bridge pier system under scour effect. The pile cap＇s weight has little influence on the static buckling load due to scour depth. In the practical bridge project, the stiffness distribution of pier and pile group can be optimized to slow down the reduction of buckling load due to scour. And the rubber bearing should be considered for the buckling ca- pacities analysis.