东海大桥桥墩基础冲刷防护方案研究

Study of Scouring Protection Schemes for Pier Foundation of Donghai Bridge

受长江、钱塘江来水来沙和人类活动的影响,东海大桥所在水域海床发生普遍冲刷,桥墩周围发生较大局部冲刷。为防止海床进一步冲深,保证该桥运营安全,对桥墩基础冲刷防护方案进行研究。根据自然条件和工程特点,主体防护区采用袋装碎石上层压载袋装混凝土干混料的防护方案;采用失效风险方法进行比选,确定周边防护区采用复合材料勾连体的防护方案。以该桥某桥墩为例,依据相关规范和研究成果,提出桥墩基础具体冲刷防护方案,开展先导性物理模型试验,依据试验结果及工程实际对防护方案进行优化。结果表明:铺设3层复合材料勾连体时防护结构整体稳定性更强,防护区内形成淤积,促进了防护体与海床的结合,对主体防护区稳定起到积极作用;优化后的防护方案总体能够满足桥墩基础冲刷防护要求。

Due to the influence of flowing water and sands from the Changjiang River and the Qiantangjiang River and human activities, the seabed in the water area where the Donghai Bridge is located has been widely scoured, and the piers have exposed to great local scouring. To protect the seabed from being further scoured and ensure the operational safety of the bridge, the scouring protection schemes for the pier foundations were studied. According to the natural environment and characteristics of the project, the protection scheme of piling up bagged rubbles and bagged dry concrete mixture (the concrete bags are on the rubble bags) at the main protection area was chosen. The failure risk evaluation was carried out, aiming to make comparisons of schemes, and the protection of using composite materials connexion for the surrounding protection area was determined. A pier of the bridge was cited as an example. Based on the relative codes and research findings, a specific anti-scouring scheme for the pier foundation was proposed. The pilot physical model test was done, based on the results of which and the condition of the actual engineering, the protection scheme was optimized. The results show that the integral stability of the protection structure was stronger when three layers of composite materials connexion were laid. The composite materials were filled up in the protection area, promoting the combination of the protection structure and the seabed, which would play an active role in sustaining the stability of the main protection area. The protection scheme after optimization can generally meet the anti-scouring protection requirements of the pier foundation.