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中南大学学报(自然科学版)

Journal of Central South University

第47卷    第2期    总第258期    2016年2月

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文章编号:1672-7207(2016)02-0548-10
现浇X形桩低应变瞬态动测响应三维有限元分析
范玉明1, 2,丁选明1,栾鲁宝1,周仕礼1

(1. 河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京,210098;
2. 上海申元岩土工程有限公司,上海,200041
)

摘 要: 建立现浇X形桩(XCC桩)低应变检测的三维有限元模型,对XCC桩的低应变瞬态动测响应进行模拟。得出桩顶不同位置的速度时域和频域响应结果,对比桩顶不同点的速度响应曲线,分析桩顶高频波传播特性,研究脉冲宽度、外包圆直径及桩身弹性模量对入射波波峰到达时间和入射波波峰值的影响。研究结果表明:XCC桩低应变瞬态动测时桩顶速度响应存在三维效应,沿尖角方向不同点的入射波峰到达时间差别明显。在接近桩心区域入射波峰值较大,且入射波之后存在反相波峰,这一现象在r>0.4R(其中,r为测点与桩心距离,R为外包圆半径)时不明显。桩顶各点的桩底反射波波形基本一致。XCC桩顶高频干扰异于实心圆桩,桩顶产生2种不同频率的高频干扰波。入射波峰到达时间和峰值受脉冲宽度和外包圆直径影响较大,受桩身弹性模量影响较小,且在XCC桩顶沿尖角方向r=0.4R处受各参数的影响最小。

 

关键词: 现浇X形混凝土桩;低应变检测;有限元法;三维效应;高频干扰

Three-dimensional finite element analysis on dynamicresponse of XCC pile in low strain integrity testing
FAN Yuming1, 2, DING Xuanming1, LUAN Lubao1, ZHOU Shili1

1. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,
Hohai University, Nanjing 210098, China;
2. Shanghai Shen Yuan Geotechnical Engineering Co., Ltd, Shanghai 200041, China

Abstract:A three dimensional finite element model was established to simulate the wave propagation in low strain integrity testing of X-section concrete pile (XCC pile). The velocity responses in time and frequency domains at different points on top of pile were obtained. By comparing the velocity responses at different points on top of pile, the high-frequency waves were analyzed, as well as the effects of pulse length, outside circle diameter and elastic modulus of pile on the arrival time and peak value of incident wave peaks. The results show that the velocity response on top of XCC pile in low strain integrity testing shows serious 3D effect, resulting in different arrival time of incident wave peaks at different points along bulge direction. The peak value of the incident waves close to pile center is the largest. The incident wave is negative after the first peak, while the negative response disappears when r>0.4R. The reflected waves from pile tip are almost the same. The high-frequency interference of XCC pile is different from solid circular piles. There are two kinds of interference frequencies on top of XCC pile. The arrival time of incident wave peaks and peak ratio of the incident and reflected waves are affected greatly by pulse length and outside circle diameter, but they are affectedlittle by elastic modulus of pile. The influence of parameters is not obvious at r=0.4R in bulge direction on top of XCC pile.

 

Key words: X-section cast-in-place concrete pile; low strain dynamic testing; finite element method; three-dimensional effect; high-frequency interference

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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