软黏土基坑开挖诱发邻近桥梁桩基的时变响应  

Time-dependent Response of Adjacent Bridge Pile Foundations Induced by Excavation in Soft Clay

作　　者：应宏伟 熊一帆[1] 吕唯 程康 刘广新 杜威 YING Hongwei;XIONG Yifan;LÜWei;CHENG Kang;LIU Guangxin;DU Wei(Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210098,China;Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China;China Railway 11th Bureau Group Co.,Ltd.,Wuhan 430061,China;Zhejiang Province Institute of Architectural Design and Research,Wenzhou 325000,China;Hangzhou Railway Design Institute Co.,Ltd.,Hangzhou 310004,China)

机构地区：[1]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210098 [2]浙江大学滨海和城市岩土工程研究中心,浙江杭州310058 [3]中铁十一局集团有限公司,湖北武汉430061 [4]浙江省铁投建设工程有限公司,浙江温州325000 [5]杭州铁路设计院有限责任公司,浙江杭州310004

出　　处：《湖南大学学报（自然科学版）》2024年第1期24-32,共9页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(51678523);中央高校基本科研业务费资助项目(B200201012);浙江省建设科研项目(2018K119)。

摘　　要：利用PLAXIS 3D软件和软土蠕变模型,建立某市政道路下穿市域铁路桥梁基坑工程的三维数值模型,通过与实测数据的对比验证模型的合理性.将软土蠕变模型退化为软土模型,考虑桩顶约束条件,对比分析桥梁群桩的时效水平响应.结合两阶段法,将数值计算得到的土体自由场时变沉降作为“外荷载”作用于桩基,利用考虑桩土往返剪切的荷载传递方法,计算桩身自重、桩顶荷载和后续近接工程基坑开挖作用下桩基的竖向力学响应.结果表明:1)土体蠕变对邻近桥梁群桩变形、内力的影响较大,甚至不亚于墙体瞬时变形的影响;2)桥梁群桩桩身的变形、内力与离开坑壁的距离呈负相关,并表现出群桩的遮帘作用,桩顶的变形、内力则由桩顶约束条件决定;3)对于桩顶承受荷载不大以及后续受近接工程基坑开挖扰动不大的深厚软弱地层中的桥桩桩基,在以桩顶变形为控制目标时,存在合理桩径和合理桩长.PLAXIS 3D software and soft soil creep model were used to establish a 3D numerical model of the excavation of a municipal road underneath an elevated bridge.The rationality of the model was verified by comparing with the measured data.The soft soil creep model was simplified into the soft soil model,and the time-dependent horizontal response of the bridge pile group was compared,taking into account the constraint condition at the pile top.The two-stage method was used to incorporate the time-dependent settlement of the soil in the free field obtained through numerical calculation as the“external load”acting on the pile foundation.The load-transfer method,which accounts for the reciprocating shear between the pile and soil,was employed to calculate the vertical mechanical response of the pile foundation under the influence of self-weight,pile top load,and excavation of the adjacent foundation pit.The results indicate that:1)Soil creep significantly impacts the deformation and internal force of adjacent bridge pile group,and its effect can be comparable to the influence of instantaneous deformation of the wall.2)The deformation and internal force of bridge pile exhibit a negative correlation with the distance between the pile and the foundation pit,highlighting the curtain effect of pile group.The deformation and internal force at the pile top are governed by the constraint condition at the pile top.3)Reasonable pile diameter and length exist for bridge pile foundations in deep soft strata where both the load on the pile top and disturbance from adjacent foundation pit excavation are minimal,when the deformation of the pile top is used as the control target.

关 键 词：基坑开挖 桩基础 时效分析 荷载传递法 

分 类 号：TU473[建筑科学—结构工程]