通过探测基础刚度评估重载铁路简支梁桥冲刷的影响

采用冲击振动试验法对一重载铁路多跨简支梁桥的自振频率进行了实际测量,根据Southwell频率合成法和能量守恒原理推导了桥墩自振频率和基础刚度之间的关系。分析了水流冲刷对桥墩基础约束刚度的影响。现场试验结果表明:大沙河特大桥桩基础受到水流冲刷作用后,自振频率会出现较为明显的下降,基础刚度下降20%左右,但依然满足设计使用需要;在桥梁实际运营养护中,对位于主河道的桥墩应进行重点关注。

Evaluation of Scour Inf luence for Simply-supported Girder Bridge on Heavy Haul Railway by Detecting Foundation Stiffness

The natural frequencies of a multi-span simply-supported girder bridge on heavy haul railway were measured by impact vibration test method.The relationship between natural frequency and foundation stiffness was deduced based on the Southwell frequency synthesis method and energy conservation principle.The inf luence of scour on the foundation stiffness was analyzed.The test results show that the natural frequencies of pile foundations of Dashahe super-large Bridge decrease obviously when they are scoured by f low .The foundation stiffness decreases by about 20 %,but still meets the requirements of design and use.In the actual operation and maintenance of bridges,it is necessary to pay more attention to the piers located in main channels.