摘要
为探明地震作用下震陷场地变截面单桩动力响应及负摩阻力特性,以翔安大桥为工程背景,通过大型振动台物理模型试验,建立了变截面单桩-软土动力相互作用模型,开展了0.10g~0.45g 5010波作用下土层震陷特性、桩身加速度、桩顶水平位移及负摩阻力研究,提出了基于震动固结原理的土层震陷量计算公式以及综合考虑软土层厚度和地震动强度的负摩阻力计算公式。研究结果表明:软土震陷量随地震波强度增大而增大,地震波强度为0.45g时,软土震陷量高达0.48 cm;提出的基于震动固结原理的软土震陷量理论计算公式与试验结果一致性较好;变截面单桩基加速度均沿地震波传递方向逐渐增大,且均在桩顶处产生加速度放大效应;桩顶加速度放大系数均大于1,放大效应随加载地震动强度的增大而减小;相同强度地震波作用下,桩端加速度峰值出现时刻早于变截面与桩顶;变截面单桩的桩顶水平位移在地震波加载前期变化比较明显,后期振幅逐渐减弱;变截面单桩负摩阻力出现在软土层以下0~3倍大截面桩径范围内,且随着地震波强度的增大而逐渐增大。综上所述,地震作用下软土震陷场地变截面单桩易产生负摩阻力效应,在工程设计中可通过优化桩基截面设计,降低负摩阻力对桥梁桩基产生的不利影响。
To clarify the dynamic response and negative frictional resistance characteristics of variable cross-section single piles in seismic subsidence sites under earthquake action,physical model tests with a large-scale shaking table were carried out with Xiang'an Bridge as the engineering background,and a dynamic interaction model of variable cross-section single piles and soft soil was established.The seismic subsidence characteristics of soil layers,pile acceleration,horizontal displacement at the pile top,and negative frictional resistance under 0.10g-0.45g 5010 wave actions were researched.A calculation formula for seismic subsidence of soil layers based on the principle of vibration consolidation and a calculation formula for negative frictional resistance comprehensively considering soft soil thickness and seismic intensity were proposed.Analysis results indicate that the seismic subsidence amount of soft soil increases with the increase of seismic wave intensity,and when the seismic wave intensity is 0.45g,the seismic subsidence amount of soft soil reaches 0.48 cm.The theoretical calculation formula of soft soil seismic subsidence based on the principle of vibration consolidation agrees well with the test results.The acceleration of variable cross-section single pile foundation gradually increases along the direction of seismic wave propagation,and an acceleration amplification effect is produced at the pile top.The amplification factor of pile top acceleration is greater than 1,and the amplification effect decreases with the increase of seismic loading intensity.Under seismic waves of the same intensity,the peak acceleration at the pile end occurs earlier than that at the variable cross-section and pile top.The horizontal displacement at the pile top of the variable cross-section single pile changes significantly in the early stage of seismic wave loading,and the amplitude gradually decreases in the later stage.The negative frictional resistance of the variable cross-section single pile occurs within the range of 0-3 times the diameter of the large-section pile below the soft soil layer,and it gradually increases with the increase of seismic wave intensity.In summary,under earthquake action,variable cross-section single piles in soft soil seismic subsidence sites are prone to negative frictional resistance effects.In engineering design,optimizing the cross-section design of pile foundations can reduce the adverse effects of negative frictional resistance on bridge pile foundations.
作者
张聪
冯忠居
彭建兵
王富春
王溪清
李玉婷
ZHANG Cong;FENG Zhong-ju;PENG Jian-bing;WANG Fu-chun;WANG Xi-qing;LI Yu-ting(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;School of Geological Engineering and Geomatics,Chang'an University,Xi'an 710064,Shaanxi,China;Baoji Administrative Service Center,Baoji 721000,Shaanxi,China)
出处
《交通运输工程学报》
北大核心
2025年第4期124-134,共11页
Journal of Traffic and Transportation Engineering
基金
国家自然科学基金项目(52378322)
陕西省科协青年人才托举计划(20250461)
长安大学中央高校基本科研业务费专项资金(300102215110)
福建省交通运输科技项目(202105)。
关键词
桥梁工程
变截面单桩
振动台试验
震陷特性
负摩阻力
bridge engineering
variable cross-section single pile
shaking table test
seismic subsidence characteristic
negative frictional resistance
