摘要
基于Biot动力波动理论描述土体饱和两相特性,提出了一种桩底土饱和虚土桩模型,同时考虑桩周、桩底饱和土体纵向成层性,采用Novak平面应变法计算得出饱和土体位移解,进一步利用饱和土-桩-饱和虚土桩完全耦合条件及阻抗函数传递性,求解得出桩顶纵向振动动力阻抗解析解,并与已有相关解析解进行退化验证及对比分析。在此基础上,探讨了桩底饱和土层厚度、桩周纵向软(硬)夹层、桩底纵向软(硬)下卧夹层、桩周及桩底饱和土体孔隙率对桩顶动力阻抗的影响规律,计算结果表明:由于单相土与饱和土压缩波波速差别较大,桩底土单相虚土桩模型会过低估计阻抗曲线共振频率,即当桩底土饱和性显著且排水性较差时,宜采用饱和虚土桩模型和所得相关解析解分析浮承桩纵向振动特性;桩周饱和软(硬)夹层对动力阻抗曲线振幅水平影响显著,而桩底软(硬)下卧夹层则对桩顶动力阻抗曲线影响很小;桩周饱和表层土体孔隙率仅对桩顶动力阻抗曲线共振幅值产生明显影响,而桩底饱和土层孔隙率对桩顶动力阻抗曲线共振幅值和共振频率均有显著影响。
Based on the Biot’s theory of wave propagation in saturated two-phase media,a saturated virtual soil pile model is proposed considering the effect of saturated soil layers beneath the pile toe.The analytical solution for displacement of saturated soil is also derived by Novak plane strain method.Then,the vertical dynamic impedance at the pile head is obtained by adopting the pile-soil compatibility conditions and the transfer method of impedance function,which is proposed to verify its validity with existing solutions.Furthermore,extensive parametric analyses are performed to investigate the effects of the thickness of the saturated soil beneath the pile toe,the longitudinal interlayer of surrounding soil,the longitudinal interlayer of soil beneath the pile toe and the porosity of saturated soil at the ground surface or beneath the pile toe on the dynamic response at the pile head.The computational results show that the resonance frequency of dynamic impedance at the pile head derived from the onephase virtual soil pile model could be underestimated due to the great difference of compression wave velocity between onephase soil and saturated soil.When the saturation of soil layers beneath the pile toe is remarkable and the drainage is poor,the saturated virtual soil pile model and the relevant analytical solution are more suitable to analyze the longitudinal vibration characteristics of floating pile.The longitudinal interlayer of surrounding soil has obvious effects on the amplitude of the dynamic impedance at the pile head.However,the effect of longitudinal interlayer of soil beneath the pile toe on the dynamic impedance at the pile head can be ignored.The effect of porosity of saturated surface surrounding soil on the resonance amplitude of the dynamic impedance at the pile head is obvious,while the porosity of saturated soil beneath the pile toe has significant effects both on the resonance amplitude and resonance frequency of the dynamic impedance at the pile head.
作者
孟坤
崔春义
许成顺
梁志孟
杨刚
MENG Kun;CUI Chun-yi;XU Cheng-shun;LIANG Zhi-meng;YANG Gang(Department of Civil Engineering,Dalian Maritime University,Dalian 116026,China;Key Laboratory of Urban Security and Disaster Engineering,Beijing University of Technology,Beijing 100124,China)
出处
《振动工程学报》
EI
CSCD
北大核心
2020年第2期372-382,共11页
Journal of Vibration Engineering
基金
国家自然科学基金面上项目(51878109,51722801,51578100)
中央高校基本科研业务费专项资金资助项目(3132014326,3132018110)
城市与工程安全减灾教育部重点实验室开放基金资助项目(201501)。
关键词
饱和虚土桩
纵向成层性
桩底土
纵向振动
动力阻抗
saturated virtual soil pile
vertical stratification
soil beneath the pile toe
longitudinal vibration
dynamic impedance
