摘要
为研究软弱土层对深长桩-土相互作用的影响,以某近海桥梁为背景,依据相似性原理制作深长群桩缩尺模型,进行拟静力试验,分析在水平荷载作用下处于软弱土层下深长桩的应变、弯矩、桩周土压力、桩周土孔隙水压力、滞回曲线和骨架曲线的变化规律。结果表明:随着位移荷载的增加,深长桩桩周土体、桩身先后出现裂缝,加载到6.75倍桩体屈服位移时,桩顶处发生折断;加载过程中,桩身应变、桩身弯矩和桩周土压力峰值均出现在桩顶附近,软弱地基的土抗力发挥主要集中在浅层;桩周土孔隙水压力沿桩深方向逐渐增大,随着位移荷载的增加,桩周土孔隙水压力的增长速度较快;随着位移荷载的增加,桩身滞回曲线的滞回环形状由狭窄的线形变为梭形再向S形过渡,桩身滞回曲线在弹塑性阶段滞回环形状相对饱满;由于淤泥质土的耗能特性,等效粘滞阻尼系数的变化范围波动幅度较小,表明在软弱土层下深长桩具有相对稳定的能量耗散能力;桩身骨架曲线的刚度退化在加载初期比较剧烈,加载后期刚度退化速率较慢。
This study investigates the influence of soft soil layers on the deep-long pile and soil interaction.Based on an offshore bridge,a scale model of deep-long pile group was prepared following the similarity principle for quasi-static tests,to analyze variation of stress,bending moment,soil pressure around pile,pore water pressure around pile,hysteresis curve and skeleton curve of the deep-long piles standing in the soft soil under horizontal loads.The results show that as the displacement loads increased,cracks occurred in the soil mass first and then in the deep-long piles,when loaded to 6.75 times of yield displacement of the pile,the pile head ruptured.During the loading process,the peak strain,bending moment and soil pressure around the pile appeared near the pile head,and the soil resistance of the weak foundation mainly concentrates in the shallow layer.Pore water pressure around the pile gradually increased downwards the pile bottom.As the displacement loads increased,the pore water pressure around the pile increased rapidly,the hysteresis loops transformed from narrow lines to spindles and to S shapes,the hysteresis loops were relatively full at the elastoplastic stage.Considering the energy dissipation characteristics of the silty clay,the equivalent viscous damping coefficient displayed minimal fluctuation,indicating that the deep-long pile in the soft soil has relatively stable energy dissipation capacity.The stiffness degradation of the skeleton curve of the pile was dramatic at the early stage of loading,and become mild at the late stage of loading.
作者
陈永锋
CHEN Yongfeng(Fuzhou Zuohai Holdings Group Co.,Ltd.,Fuzhou 350028,China)
出处
《世界桥梁》
北大核心
2025年第3期64-71,共8页
World Bridges
基金
国家自然科学基金项目(52278159)。
