管桩在低应变瞬态集中荷载作用下的速度响应研究

【作者】 罗文章；

【导师】 陈凡；

【作者基本信息】 中国建筑科学研究院 ， 岩土工程， 2002， 硕士

【摘要】 近十年来，预应力管桩在我国尤其是广东上海等沿海地带得到了广泛的应用。目前为检测其桩身完整性应用最多的方法是低应变反射波法。本文通过有限元这种数值方法对应力波在管桩中的传播现象进行了较为全面的研究，以对实际的检测有所帮助。 本文首先研究了应力波在管桩顶面的传播及其影响，并提出了计算不同点激励速度峰值时间差的关系式。本文最重要的工作是通过数值计算与实验的对比确定点击脉冲荷载作用下传感器的最佳接收位置，即距离加载点相对于管桩截面中心夹角为90°的点。在此点处，高频干扰随加载脉冲的变宽迅速衰减，本文从振型的角度给予了解释。这个结论对实际检测具有很重要的意义。本文还对影响高频干扰的其它因素，影响深度，缺陷桩情况等问题做了一定的研究。 当然，运用有限元法求解诸如本课题的动力学的问题，必须做一些简化。如何更好地简化以接近实际情况，或者通过数学简化得到一个理论解，需要更进一步的工作。更多还原

【Abstract】 In recent years,prestressed pipe piles become more and more popular day by day in China,especially in Guangdong Province and Shanghai City etc.. Now the most available method of pile integrity testing is low strain pile integrity test(LSPIT). With the help of finite element method (FEM),stress wave propagation in pipe piles was studied in this paper for the benefit of engineering tests.At first,the propagation and influence of stress wave on the top of the pipe pile were discussed in the paper and a formula was obtained about the time difference between two initial signals which were received from two different points. The main achievement of the paper is to recommend the 90 point as the best place for sensor by the contrast of numerical calculation results and test signals. On the point the high frequency disturbing signal was weakened very much when the load impulse was changed,which could be explained when vibration shape was considered. Other factors that would influence the high frequency disturbing signal,the influential depth and defect piles were also discussed in the paper.Certainly,the dynamic problems such as what discussed in this paper was simplified. More work need to do for a better case which approaches to an engineering pile or a good theory result.更多还原