液化场地大直径变截面单桩群桩动力响应差异  

Difference in Dynamic Response of Large Diameter and Variable Cross Section Single and Group Piles in Liquefied Sites

作　　者：冯忠居[1] 周世昊 张聪[1] 宋健 林立华 Feng Zhongju;Zhou Shihao;Zhang Cong;Song Jian;Lin Lihua(Highway School,Chang'an University,Xi'an 710064,P.R.China;Xiamen Road and Bridge Engineering Investment and Development Co.,Ltd.,Xiamen,Fujian 361000,P.R.China)

机构地区：[1]长安大学公路学院,西安710064 [2]厦门路桥工程投资发展有限公司,福建厦门361000

出　　处：《地下空间与工程学报》2025年第1期198-206,共9页Chinese Journal of Underground Space and Engineering

基　　金：福建省交通运输科技项目(202105);海南省交通科技项目(HNZXY2015-045R);国家自然科学基金青年科学(4190070568)。

摘　　要：为研究地震作用下大直径变截面群桩基础在与单桩基础抗液化性能方面的差异,依托第二东通道工程,采用振动台模型试验开展大直径变截面单桩、群桩基础动力响应差异性研究,分析了饱和砂土层中大直径变截面单、群桩在地震荷载下,孔压比、桩身加速度、桩顶水平位移和桩身弯矩差异。结果表明:地震荷载为0.30 g,大直径变截面单桩与群桩工况下,基础均发生液化现象,大直径变截面群桩基础完全液化时刻比单桩基础延缓1.58~1.64 s;大直径变截面群桩桩身最大加速度较单桩减小,且出现时刻较单桩更为滞后;大直径变截面群桩桩顶最大水平位移较单桩减小0.68 mm,出现时刻滞后1.44 s;大直径变截面群桩基础最大弯矩值较单桩基础减小11.99%,大直径变截面群桩基础最大弯矩出现时刻较单桩基础滞后1.88 s;大直径变截面群桩基础的抗液化特性明显高于单桩基础,动力响应更为滞后,在地震区桩基础设计中,可考虑用大直径变截面群桩基础形式增加其抗液化特性。With the purpose of researching the distinctions between the anti liquefaction capability of large-diameter variable cross-section group piles foundation and single pile foundation under earthquake condition,relying on the Second East Passage Project,the dynamic response difference of large-diameter variable cross-section single pile and group piles foundation was studied by vibration table model testing,and the difference of pore pressure ratio,pile shaft acceleration,pile top horizontal displacement and pile shaft bending moment between large-diameter variable cross-section single pile and group of piles in saturated sandy soil under earthquake load was analyzed.The research results show that under the seismic load of 0.30 g,the foundation of large diameter and variable crosssection single pile and pile group are liquefied,and the complete liquefaction time of large diameter and variable cross-section group piles foundation is 1.58~1.61 s later than that of single pile foundation;The maximum acceleration of large diameter variable cross-section group piles is reduced compared to single piles,and the occurrence time is more delayed than single piles;The maximum horizontal displacement of the top of a large diameter variable cross-section pile group is reduced by 0.68 mm compared to a single pile,with a time lag of 1.44 seconds;The maximum bending moment of large diameter variable cross-section group piles foundation is 11.99%less than that of single pile foundation,and the maximum bending moment of great diameter variable cross-section group piles foundation lags 1.88 s behind that of single pile foundation;It reveals that the anti liquefaction features of large diameter and variable cross-section group piles foundation are significantly higher than that of single pile foundation,and the dynamic response is more delayed.In the design of pile foundation in earthquake area,the anti liquefaction features of large diameter and variable cross-section group piles foundation can be increased by using the form of large

关 键 词：大直径变截面 地震荷载 振动台试验 群桩基础 液化 

分 类 号：U443[建筑科学—桥梁与隧道工程]