大型桥梁冲刷防护工程损坏特性研究

Study on failure characteristics of scour protection engineering of large bridges

以苏通大桥为例．通过模型试验和冲刷防护工程及周边河床地形的长期监测开展了大型桥梁冲刷防护工程的损坏特性研究。研究结果表明，大型桥梁冲刷防护工程存在两种损坏形式：防护工程防护区面层冲刷损坏和防护工程护坦边坡坍塌损坏；防护工程的破坏主要发生在防护工程后1—2年内。提出了以“损坏率”和“稳定边坡”分别表示两种不同类型的破坏指标。同时，提出了防护工程“成型稳定工程量基准线”概念，为监测冲刷防护工程稳定性制定定量目标。研究结果还表明，在防护体稳定后，防护区呈“洪季淤积、枯季冲刷”特点，这一变化对防护体稳定影响有限。研究结果为类似工程设计、监测、维护和相关研究提供参考。

Taking Sutong Bridge as an example, long-term monitoring on scour protection engineering and riverbed terrain and model test are applied to study the failure mechanism of scour protection engineering. The resuhs show that there are two forms of failure in scour protection for large bridges in tidal reach, which are erosion on surface and collapse of slope of aprons ; and they usually occur in 1 to 2 years after engineering acceptance. Damage rate and steady slope are suggested for failure index for two forms of failure respectively. Meanwhile, shaping security reference line is proposed based on results of long-term monitoring. When the size of protection engineering is less than the shaping security reference line, failure would take place. Moreover, the results also show that changes of protection zone are caused by sediment erosion or siltation on surface after engineering adapted with surrounding current and terrain; and these changes have no significant effect on stability of protection engineering. The research results can provide references for bridge design and related studies.