大直径PHC管桩水平承载特性及比例系数m取值  

Horizontal Bearing Characteristics of Large Diameter PHC Pipe Pile and Proportional Coefficient m

作　　者：周洋 ZHOU Yang(China Railway 24th Bureau Group Corporation Limited,Shanghai 200433,China)

机构地区：[1]中铁二十四局集团有限公司,上海200433

出　　处：《铁道建筑》2024年第11期83-89,共7页Railway Engineering

基　　金：中铁二十四局集团有限公司基金(SY-20230616)。

摘　　要：我国黄河冲积平原广泛分布粉土和粉砂,途经该地区的津潍(天津—潍坊)高铁桥梁大范围采用直径1 m的预应力高强混凝土(Prestressed High-strength Concrete,PHC)管桩。该地层中大直径管桩的水平承载特性不明,关键设计参数水平地基系数的比例系数(m)取值不清,影响高铁桥梁桩基设计的经济性和安全性。本文采用慢速维持荷载法对深厚粉土和粉砂地区2根大直径管桩进行水平静载试验。结果表明:以水平临界荷载为分界点,桩顶水平位移随着荷载的增加由近似呈线性增长转为非线性增长,桩周土由弹性转换为塑性状态,且塑性区不断扩大。随桩顶水平荷载的增大,桩身弯矩相应增大,弯矩最大值出现在水平荷载作用点以下3~4 m。粉土和粉砂层综合m值随水平位移的增大呈幂函数衰减,考虑工作折减系数后,m值取5.536 MN/m^(4)。Silt and silty sand are widely distributed in the alluvial plain of the Yellow River in China.The Tianjin-Weifang high speed railway bridge passing through this area extensively uses prestressed high intensity concrete(PHC)pipe piles with a diameter of 1 m.The horizontal bearing characteristics of large diameter pipe piles in this stratum are unknown,and the proportional coefficient m of the key design parameter horizontal foundation coefficient is unclear,which affects the economic and safety design of high speed railway bridge pile foundations.Horizontal static load tests were conducted on two large diameter pipe piles in areas with deep loess and silty sand using the slow maintenance load method.The results show that with the horizontal critical load as the boundary point,the horizontal displacement of the pile top changes from approximately linear growth to nonlinear growth with the increase of load,and the soil around the pile transitions from elastic to plastic state,with the plastic zone continuously expanding.As the horizontal load on the pile top increases,the bending moment of the pile also increases accordingly,and the maximum bending moment occurs 3~4 m below the point of horizontal load.The comprehensive m value of the silt and silty sand layers decays with a power function as the horizontal displacement increases.After considering the work reduction coefficient,the m value is taken as 5.536 MN/m^(4).

关 键 词：大直径PHC管桩 水平静载试验 承载特性 M值 桩身内力 

分 类 号：U443.15[建筑科学—桥梁与隧道工程] U448.13[交通运输工程—道路与铁道工程]