基于LS-DYNA的桩顶约束混凝土基桩的低应变动测数值研究

以一维应力波理论为基础,运用有限元显式分析方法,对混凝土桩在桩顶自由和桩顶受约束时的低应变动测进行数值模拟;并对比两种情况下的动测曲线,发现桩顶受约束时桩的动测曲线不仅受桩周土体的影响,还受到上部结构的干扰,并且桩身反射的三维效应更明显。然后,通过信号处理得到桩顶受约束的混凝土桩的滤波信号,使这种情况下的混凝土桩的缺陷识别更加简便和准确。最后,通过对模拟曲线与实测曲线的较好拟合,表明基于有限元显式分析方法的桩基检测模拟是可靠的,所得结论对于提高混凝土桩低应变动测的准确性具有一定的指导意义。

NUMERICAL STUDY OF THE LOW STRAIN DYNAMIC TEST OF RESTRICTED PILE TOP OF CONCRETE PILE

Based on the one-dimension stress wave theory,the low strain dynamic test of concrete pile whose top is restricted or not is studied by finite element explicit analysis method.The dynamic tests of top-restricted concrete pile are affected not only by the soil around pile,but also by the upper structure,and the signal of 3D effect reflected by the pile is stronger.Then,the interference of the upper structure is filtered through signal progress.Finally,the simulated curves are in good agreement with those obtained from field measurements.So the simulation of concrete pile dynamic test is reliable and the conclusion may be a guidance of increasing the accuracy of the low strain dynamic test of concrete pile.