软土地区航道开挖对桥梁桩基变形影响研究

Influence of channel excavation on the deformation of bridge pile foundation in soft soil area

摘要:

以京杭运河二通道海宁段东西大道桥某桥梁桩基为研究对象,针对陆上航道开挖穿越密集交叉点重要桥梁工程的建设施工和安全防护的科学和技术难题开展研究。运用现场勘察,室内试验和三维数值仿真技术,对研究区深厚软土地质条件下的航道开挖进行模拟计算,分析航道开挖卸载过程中邻近桥梁桩基水平偏转位移,并重点探究桥梁桩基受邻近航道开挖关于不同桩长、桩径对桩基水平偏移的影响规律。结果表明:航道开挖工程势必会引起土体扰动而造成桩基偏移,对于超长桩来说,增大桩径对于桩基水平承载力的提升与控制桩基水平倾斜帮助有限;对于软土地区桥梁桩基来说,其桩长应大于临界值,否则桩基水平承载力不足以抵消土的开挖扰动对于桩的影响力,使得桩的水平倾斜急剧增大,使之发生破坏。研究成果可为后续相类似的工程及施工提供参考依据。

Abstract:

Taking the pile foundation of a bridge in Haining section of the second passage of Beijing-Hangzhou Canal as the research, the scientific and technical problems of the construction and safety protection of important bridge projects crossing dense intersections during the excavation of overland waterway were studied. Through on-site investigation and indoor tests, the channel excavation in deep soft soil of the study area was simulated and calculated by using the 3D numerical simulation technology. The horizontal offset of adjacent bridge pile foundation during the channel excavation was analyzed, and the influence of different pile length and pile diameter on the horizontal offset of bridge pile foundation caused by adjacent channel excavation was mainly explored. The results show that the excavation of waterway will inevitably cause soil disturbance and displacement of pile foundation. For super-long piles, the increase in the pile diameter is of limited help in improving the horizontal bearing capacity and controlling the horizontal inclination of pile foundation. The pile length of bridge pile foundation in soft soil area should be greater than the critical value, otherwise, the horizontal bearing capacity of the pile foundation is not enough to offset the influence of soil excavation on the pile, which will lead to a sharp increase in the horizontal inclination of the pile and cause damage. The research results can provide reference for similar projects and construction in the future.