临河软弱地层桥梁微型桩力学特性与优化设计

Mechanical characteristics and optimization design of bridge micro-pile in soft stratum adjacent to river

针对临河软弱地层桥梁微型桩力学特性与优化设计问题,以“一带一路”重点贡献项目格鲁吉亚E60高速公路Ubisa-Shorapani(F3)标段工程为主要依托,利用数值模拟分析桩体重要参数对力学性能及变形影响,并将模拟结果与现场监测数据对比分析。结果表明:桩径从180 mm变化至260 mm,桩体最大水平位移减小5.52 mm,降幅为31.1%,据此在工程实际中可通过增大桩径有效控制桩体位移;桩间距由280 mm增加至360 mm,桩身最大水平位移仅增加2.5 mm,同时桩数量减少,可见桩间距的调整对经济性起到关键作用;钢管壁厚与钢管直径等差变化时,钢管壁厚对桩体水平位移影响效果较为显著;调整环梁竖向间距能改变不同深度处桩体水平位移,其中在桩顶0~2 m深度范围内的水平位移随间距改变变化最为明显。根据上述结果确定的微型桩优化方案在工程中运用显示,理想效果。

Aiming at the problems of the mechanical properties and optimization design of the bridge micro-pile in soft stratum adjacent to river, the key contributive project of China-proposed Belt and Road Initiative — the Ubisa-sarapani(F3) bid section of Georgia E60 International Expressway is taken as the main basis, and then the influences from the important parameters of the pile body on the mechanical properties and deformation are analyzed with the relevant numerical simulation, while the simulated results are compared with the related in-situ monitoring data as well. The results show that the maximum horizontal displacement of the pile body is to be decreased by 5.52 mm with the decreasing amplitude of 31.1% when the pile diameter is changed from 180 mm to 260 mm, thus the displacement of the pile body can be controlled through increasing pile diameter in the actual engineering practice. When the pile spacing increases from 280 mm to 360 mm, the maximum horizontal displacement of the pile body can only increase by 2.5 mm and the number of piles is to be decreased at the same time, thus the adjustment of the pile spacing plays a key role in the safety and economy of the optimal design of the project. When the equal difference between the wall thickness of the steel pipe and the steel pipe diameter is changed, the effect of the wall thickness of the steel pipe on the horizontal displacement of the pile body is significant. The horizontal displacements of the pile bodies at different depths can be changed through adjusting the vertical spacing of the ring beams, in which the change of the horizontal displacement within the range of 0~2 m depth of pile top is most obvious. The finally determined optimization scheme of the micro-pile is successfully applied to the project with ideal effect.