季节冻土区铁路挖井基础桥墩地震破坏特征及抗震性能影响因素  

Seismic Failure Characteristics and Seismic Performance Influence Factors of Railway Piers on Digging Well Foundation in Seasonally Frozen Soil Region

作　　者：张熙胤[1] 于生生 王义 王万平 丁明波[1] 马华军[1] ZHANG Xiyin;YU Shengsheng;WANG Yi;WANG Wanping;DING Mingbo;MA Huajun(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou Gansu 730070,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070

出　　处：《中国铁道科学》2022年第4期18-29,共12页China Railway Science

基　　金：甘肃省科技计划项目-杰出青年基金(20JR5RA430);中国博士后科学基金面上项目(2018M643767);第五届中国科协青年人才托举工程项目(YESS20200278);兰州交通大学天佑青年人才托举工程项目(1520260110)。

摘　　要：以西北季节冻土区广泛采用的挖井基础桥墩为研究对象,运用ABAQUS有限元软件,建立土-挖井基础-桥墩相互作用体系有限元模型,通过拟静力模型试验验证其合理性,并基于该模型分析季节冻土区铁路挖井基础桥墩的地震破坏特征及抗震性能影响因素。结果表明:在地震作用下,存在季节冻土层时浅埋挖井基础桥墩的破坏模式从无冻土时基础周围土体的破坏转变为桥墩本身不同程度的破坏;与非冻结条件相比,存在0.2和0.4 m厚冻土层时,土-挖井基础-桥墩体系的峰值荷载分别提高了约76%和148%,累积耗能增加了约121%和167%;当表层冻土完全融化时,体系的峰值荷载下降接近70%,累计耗能仅为0.4 m厚冻土层时的21.4%;基础埋深的增加可有效提高季节冻土区挖井基础桥墩的抗震性能,但也会增加桥墩混凝土的破坏程度;墩身配筋率对埋深较小的挖井基础桥墩水平承载力影响较小。This paper took the piers on digging well foundation widely applied in seasonally frozen soil regions of Northwest China as research objects.A finite element model of soil-digging well foundation-pier interaction system was established using ABAQUS finite element software and the model rationality was validated by the quasi-static model test.Based on the proposed model,the seismic failure characteristics and seismic performance influence factors of railway piers on digging well foundation in seasonally frozen soil regions were further analyzed.The results showed that the existence of seasonally frozen soil layer changed the failure mode of the shallow buried piers on digging well foundation under seismic actions.The failure of the soil surrounding the foundation with unfrozen soil turned into the failure of the pier to different extents.Compared with the unfrozen condition,the peak load of soil-digging well foundation-pier system increased by 76%and 148%,respectively,and the cumulative energy dissipation increased by 121%and 167%with 0.2 and 0.4 m thick frozen soil layers,respectively.However,when the surface frozen soil thawed completely,the peak load of the system decreased by nearly 70%,and the cumulative energy dissipation was only 21.4%with 0.4 m thick frozen soil layer.The increase of foundation embedded depth could effectively improve the seismic performance of the piers on digging well foundation in seasonally frozen soil regions,but the failure degree of the pier concrete would also be aggravated.The reinforcement ratio of pier had little effect on the horizontal bearing capacity of the pier on digging well foundation with smaller embedded depth.

关 键 词：铁路 桥梁 挖井基础桥墩 季节冻土区 地震 破坏特征 抗震性能 影响因素 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]