考虑桩土相互作用的变阻抗桩纵向振动特性  

Longitudinal Vibration Characteristics of Variable Impedance Pile with the Consideration of Soil-Pile Interaction

作　　者：胡昌斌[1] 王国业[2] 

机构地区：[1]福州大学土木工程学院,福建福州350002 [2]沈阳建筑大学科技产业处,辽宁沈阳110168

出　　处：《沈阳建筑大学学报（自然科学版）》2009年第3期456-461,共6页Journal of Shenyang Jianzhu University：Natural Science

基　　金：国家自然科学基金项目(50279047);福建省高等学校新世纪优秀人才计划项目(TW2006-27)

摘　　要：目的揭示竖向动力荷载下变阻抗桩与土相互作用时的振动特性.方法从三维轴对称模型出发建立了定解问题,利用拉氏变换手段和阻抗函数的传递性,推导求解了任意段变阻抗桩纵向振动时桩顶频域响应理论解,并进行了参数影响分析.结果分析表明存在临界桩长,此桩长以内缩颈桩动刚度及阻尼相比正常桩较小,扩颈桩则较大,变截面桩动刚度及阻尼在频域有大峰夹小峰现象.桩缺陷段长度、大小对桩顶影响与位置密切相关,变模量桩有类似规律,但与正常桩相比,桩底反射时间不同.结论笔者提出的考虑桩土相互作用的变阻抗桩纵向振动理论解,与桩土众多常规参数建立了明确关系,相比W inkler和平面应变解可以考虑桩土三维波动效应,具有更高的精度和适用性,为桩基抗震、防震分析与设计提供了参考依据.The paper aims to reveal vibration characteristics of variable impedance pile to a vertical dynamic load at the pile head by considering the interaction between soil and pile. Through a 3D axisymmetric model, the definite problem was established, and by Laplace transforms and the transmit property of impedance function, the analytical expression for frequency domain response of an arbitrary segment of variable impedance pile during longitudinal vibration was derived. The parameter analysis was also carded out. The analysis shows that within the critical length of pile, both the dynamic stiffness and the damping of the necking pile are smaller than a normal pile, but the expanding one is opposite, and it also finds that the phenomenon of the small peak clip in big peak exists in the phase-frequency curve for the variable section pile. And the influence on the pile head response due to the length and degree of a defective pile segment is closely related to its location. In addition, the variable modulus pile has the similar rule, but the reflex time at its pile bottom is different from a normal pile. The theoretical solution proposed by authors for the longitudinal vibration of variable section impedance pile with considering the interaction between soil and pile establishes a clear connection between its parameters and conventional soil-pile parameters. Meanwhile, compared with the Winkler solution and the plane strain solution ,it can not only consider the 3D wave effect,but also has higher precision and applicability. Hence, it can provide a reference basis to the analysis and design of seismic and earthquake prevention in pile foundation.

关 键 词：桩土相互作用 变阻抗 纵向振动 时域 频域 

分 类 号：TU473[建筑科学—结构工程]