公路下穿既有线新建泡沫轻质土路涵过渡段动力响应特性分析  

Analysis of dynamic response characteristics of road subgrade-culvert transition section newly constructed with foamed lightweight soil under-crossing existing railway line

作　　者：刘彬彬 曾志姣 杨晨 卢洺宇 黄俊杰[3] LIU Binbin;ZENG Zhijiao;YANG Chen;LU Mingyu;HUANG Junjie(China Railway Wuhan Survey and Design Institute Company Limited,Wuhan 430074,China;Guangdong Communication Planning and Design Institute Group Co.,Ltd.,Guangzhou 510507,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]中铁武汉勘察设计研究院有限公司,湖北武汉430074 [2]广东省交通规划设计研究院集团股份有限公司,广东广州510507 [3]西南交通大学土木工程学院,四川成都610031

出　　处：《铁道科学与工程学报》2022年第6期1577-1584,共8页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52078434);中国铁路武汉局集团有限公司科研项目(19G25);四川省科技计划项目(重大前沿)(2016JY0005)。

摘　　要：当公路下穿既有铁路线时需要在既有铁路路堤中新建一路涵过渡段,控制其差异沉降是公路与铁路线路交叉工程建设的关键技术难题之一。引入泡沫轻质土作为新建路涵过渡段的填料以更有效地控制其差异沉降,是公路与铁路线路交叉工程建设的一种新探索。为了研究在既有铁路路堤中新建泡沫轻质土路涵过渡段的动力特性,依托武汉市李纸路下穿既有铁路线而新建的路涵泡沫轻质土过渡段工程,开展了一系列的路涵泡沫轻质土过渡段现场行车动态测试。测试结果表明:在时速为60 km/h和行驶方向为土质路基至涵洞方向的行车作用下,泡沫轻质土过渡段区间内轨枕的最大振动位移、速度和加速度分别在0.59~2.04 mm,5.82~13.3 mm/s和0.43~3.03 m/s^(2)之间,轨枕最大振动位移和加速度由泡沫轻质土过渡段末端向涵洞方向均呈逐渐递减规律。各监测断面基床表层顶面和底面最大动应力分别在23.19~24.37 kPa范围和在19.52~20.73 kPa范围,泡沫轻质土过渡段底部最大动应力为0.55 kPa,最大动应力沿深度方向呈逐渐衰减规律,至基床表层底面衰减15%~20%,说明采用设计湿密度为700 kg/m^(3)的泡沫轻质土作为过渡段基床底层及以下区域的填料均能满足静动强度要求;在线路纵向上远离涵洞方向呈逐渐减小规律,衰减趋势较为平缓。综合反映采用泡沫轻质土填筑既有铁路新建的路涵过渡段实现了动力响应的平稳过渡。A subgrade-culvert transition section needs to be built in the existing road embankment when the highway passes under the existing railway line.Controlling the differential settlement of the subgrade-culvert transition section is one of the key technical problems in the construction of highway and railway line crossing projects.Using foamed lightweight soil as the filler of the new subgrade-culvert transition section to more effectively control its differential settlement is a new exploration for the construction of highway-railway crossing projects.In order to study the dynamic characteristics of the subgrade-culvert transition section newly constructed with foamed lightweight soil in the existing embankment,a series of on-site dynamic tests under the train operation were carried out based on the new construction project of the subgrade-culvert transition section filled with foamed lightweight soil caused by Lizhi Road under-crossing existing railway line in Wuhan.The results show that the maximum vibration displacement,velocity and acceleration of the sleepers of the track structure on the transition section under the train operation running at 60 km/h from the soil subgrade to the culvert range from 0.59~2.04 mm,5.82~13.3 mm/s and 0.43~3.03 m/s^(2),respectively.The maximum vibration displacement and acceleration of the sleepers gradually decrease from the end of the transition section to the direction of the culvert.The maximum dynamic stress at the surface and bottom of the top layer of the subgrade bed of each monitoring section range from 23.19 kPa to 24.37 kPa and 19.52~20.73 kPa,respectively.The maximum dynamic stress at the bottom of the foamed lightweight soil section is 0.55 kPa.The maximum dynamic stress decreases gradually with increasing depth,and decreases by 15%~20% from the surface to the bottom of the foamed lightweight soil section.It shows that the foam light soil with a design wet density of 700 kg/m^(3) can be used as the filler for the bottom layer of the subgrade bed in the transition sect

关 键 词：路涵过渡段 泡沫轻质土 现场测试 动力特性 

分 类 号：U213.1[交通运输工程—道路与铁道工程]