静钻根植桩低应变动力响应的现场试验和数值模拟

doi:10.16183/j.cnki.jsjtu.2020.04.009

摘要/Abstract

摘要： 针对静钻根植竹节桩的成桩特性，通过现场试验和有限元数值模拟，研究桩周水泥土随着龄期变化对竹节桩低应变测试曲线的影响.首先通过现场试验，得到现场试桩在水泥土不同龄期的低应变曲线，发现桩端反射信号的幅值和到达速度均受到水泥土硬化的影响；同时通过室内弯曲元试验，测得不同龄期下相同配合比水泥土的切变模量；然后通过多次反演拟合，建立三维有限元数值模型，结合室内试验结果，对竹节桩低应变测试特性进行研究；接着将模型曲线与实测曲线进行对比，重点研究了桩端低应变反射信号的幅值和综合波速，两者曲线特性符合良好；最后对三维有限元数值模型进行参数分析，分析桩周普通土和桩底土切变模量对桩身低应变曲线的影响.结果表明：桩周水泥土在随着龄期硬化期间，会导致桩端反射信号幅值逐渐变小，在5 d以后已较难分辨；同时，低应变测试的综合波速也会随之增大，但是均明显小于竹节桩在地表时的波速，该数值模型能较好的模拟静钻根植竹节桩的低应变动力特性；参数分析说明，桩身低应变测试的综合波速变化与桩周普通土和桩底土的切变模量变化无关，仅由桩周水泥土引起.

关键词: 静钻根植竹节桩, 水泥土, 低应变测试, 波速, 现场试验, 数值模拟

Abstract: In order to investigate the effect of cemented soil on dynamic response of static drill rooted pile, field tests and numerical simulation methods were employed. At first, field tests were performed to acquire the time domain curves of pile by low-strain testing, indicating that the amplitude and the arrival time of the reflected signal from pile tip were both affected by the cemented soil. Then, the shear moduli of cemented soil in different ages were obtained by bending element test. Afterwards, a three-dimensional finite element numerical model was established based on the tests on cemented soil, focusing on the amplitude of the reflected signal and wave velocity. After that, a comparison between the results of field tests and numerical simulation was presented, demonstrating good agreement. Finally, a parameter study for the effect of soil’s modulus was presented. The above research indicated that the modulus of cemented soil influenced both the amplitude of the reflected signal and the wave velocity of the pile. The numerical model could well simulate the dynamic response of the pile in low-strain test, and could be used for further research. The modulus of surrounding and base soil had no influence on the wave velocity of the pile.

Key words: static drill rooted nodular pile, cemented soil, low-strain test, wave velocity, field test, numerical simulation

中图分类号:

TU 473

肖偲, 王奎华, 张日红, 王孟波. 静钻根植桩低应变动力响应的现场试验和数值模拟[J]. 上海交通大学学报, 2020, 54(4): 406-412.

XIAO Si, WANG Kuihua, ZHANG Rihong, WANG Mengbo. Field Test and Numerical Simulation for the Dynamic Response of Low-Strain Testing on Static Drill Rooted Pile[J]. Journal of Shanghai Jiao Tong University, 2020, 54(4): 406-412.

参考文献

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