高速铁路X形桩桩网复合地基动态响应分析  

Dynamic response analysis of X-pile-net composite embankment in high-speed railway

作　　者：牛婷婷[1,2] 孙广超 NIU Ting-ting;SUN Guang-chao(College of Civil Engineering and Architecture,Anhui University of Science and Technology,Huainan,Anhui 232001,China;College of Civil and Transportation Engineering,Hohai University,Nanjing,Jiangsu 210098,China;Key Laboratory of Geological Hazards on Three Gorges Reservoir Area,China Three Gorges University,Yichang,Hubei 443002,China)

机构地区：[1]安徽理工大学土木建筑学院,安徽淮南232001 [2]河海大学土木与交通学院,江苏南京210098 [3]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002

出　　处：《岩土力学》2021年第5期1266-1280,共15页Rock and Soil Mechanics

基　　金：安徽省自然科学基金项目(No.2008085ME143);安徽理工大学博士基金项目(No.13190018)。

摘　　要：桩网复合地基在高速铁路建设中的应用越来越广泛,但其在动态列车荷载作用下的响应机制尚不甚清楚,这使得对高速列车荷载作用下桩网复合地基的研究显得十分迫切。为此,建立了大比尺X形桩网复合地基模型,研究了地基土-X形桩-加筋垫层-路堤-轨道系统的动态响应特性。结果表明:随着列车速度和轴重的增加,动土压力、动位移、动应变、振动速度等的响应幅值均在增大。由于波在桩-土界面的反射作用,桩底动土压力大于桩顶动土压力。与无桩无网的路堤相比,桩网复合地基减振效果显著。桩顶正上方格栅动应变响应幅值的增长幅度约是桩间土正上方格栅动应变响应幅值增长幅度的2倍。X形桩桩身中部和桩底的瞬态动应变较大。同一位置处,加载频率对振动速度的影响远大于加载幅值对其影响;与路堤表面相比,复合地基内部振动速度的增长幅度受加载频率的影响更大。在地基面以上路堤部分检测到了"类共振"现象,在铁路建设中可以通过改变路堤刚度避免出现此现象。Pile-net composite embankments are more and more widely used in high-speed railways construction,but the response mechanisms under the dynamic train load are still unclear.In this paper,a large-scale X-pile-net composite embankment model is established,and the dynamic response characteristics of a system consisting of subsoil,X-piles,reinforced cushion,the embankment,and track slab are investigated.The results show that as the train speed and axle load increase,the response amplitudes of the dynamic earth pressure,dynamic displacement,dynamic strain,and vibration speed increase as well.Due to the reflection of M-shaped wave at the interface between the pile tip and subsoil,the dynamic earth pressure exerted on the pile is larger than that on the pile.Compared to the embankment without piles and nets,the reduction effect of vibration on the piled embankment is remarkable.The increase in the dynamic strain of the geogrid above the pile is about 2 times that of the geogrid above the subsoil between of two piles.The transient dynamic strain in the middle and bottom of X-pile is larger.At the same location,the influence of loading frequency on the vibration velocity is much greater than that of loading amplitude.Compared with the surface of embankment,the increase in vibration velocity within the piled embankment is more affected by the loading frequency.The phenomenon of"resonance-like"has been detected in the embankment above the subsoil,which could be avoided by changing the rigidity of the embankment when building railways.

关 键 词：动态响应 高铁铁路 桩网复合地基 X形桩 

分 类 号：TU473[建筑科学—结构工程]