桩体异常反射波响应特征及其模拟应用研究

发布时间：2018-05-18 14:18

本文选题：桩基 + 低应变反射波法　；参考：《安徽理工大学》2017年硕士论文

【摘要】：随着建筑规模的不断扩大,地基处理深度的不断加大,桩基在工程中的使用越来越广泛。桩的完整性对工程安全有着必然的联系,若桩出现缺陷很容易影响桩基的承载力从而造成工程人力、物力和财力的损失,所以如何检测桩的完整性在工程中是一项必不可缺的关键环节。由于工程环境复杂、桩的缺陷类型繁多,给桩的完整性检测带来一定的难度。若不研究缺陷桩的响应特征,很容易造成混淆以至于无法进行专门的预防治理。结合工程实际问题,文章采用数值模拟和现场检测等手段对低应变反射波法检测技术开展研究。文章结合低应变反射波法技术研究现状进行讨论,阐述了一维波动理论并给出了达朗贝尔解,表明了纵波在桩基中传播的基本特性。同时根据应力波与位移波的反射系数,为基桩的反射曲线分析奠定了深厚的理论基础。利用ABAQUS数值软件对不同规格的完整性桩,含有单一缺陷的桩,含有组合缺陷的桩进行数值模拟,从时域的角度研究了混凝土强度、冲击荷载、长细比和土层因素对完整性桩的影响,同时研究了断桩、离析桩、缩径桩、扩径桩以及组合缺陷桩的相位、波幅等基本特征,对比和分析了各类桩的低应变反射波的响应曲线特征。为验证桩的异常响应特征以及低应变反射波检测方法的准确性,采用桩基应变仪对现场5根测试桩和5根工程桩进行了检测,从时域与频域两个角度分析了桩体反射波特征,对其完整性进行了评价,为工程现场检测应用提供参考。研究表明低应变反射波法在基桩完整性检测方面有很明显的优势,适宜对不同类型桩体进行测试,但在检测技术方面仍存在一些问题需要进一步研究。
[Abstract]:With the continuous expansion of construction scale and the increasing depth of foundation treatment, pile foundation is more and more widely used in engineering. The integrity of the pile has a certain connection to the safety of the project. If the pile is defective, it will easily affect the bearing capacity of the pile foundation, resulting in the loss of human, material and financial resources. So how to detect the integrity of pile is an indispensable key link in engineering. Because of the complex engineering environment and various types of pile defects, it is difficult to check the pile integrity. If the response characteristics of defective piles are not studied, it is easy to cause confusion, so that special preventive measures cannot be carried out. Combined with practical engineering problems, this paper studies the detection technology of low strain reflection wave method by means of numerical simulation and field detection. In this paper, the present research situation of low strain reflection wave method is discussed, the one-dimensional wave theory is expounded and the Darumbelian solution is given, which shows the basic characteristics of the longitudinal wave propagating in the pile foundation. At the same time, according to the reflection coefficient of stress wave and displacement wave, it lays a deep theoretical foundation for the analysis of the reflection curve of foundation pile. Using ABAQUS software to simulate the integrity pile with different specifications, the pile with a single defect and the pile with a composite defect, the strength and impact load of concrete are studied from the point of view of time domain. The influence of aspect ratio and soil layer factors on the integrity pile is also studied. At the same time, the phase and amplitude of the broken pile, the separated pile, the shrunk pile, the expanded diameter pile and the composite defective pile are studied. The characteristics of response curves of low strain reflected waves of various piles are compared and analyzed. In order to verify the abnormal response characteristics of pile and the accuracy of low strain reflection wave detection method, five test piles and five engineering piles were tested by pile foundation strain meter. The characteristics of reflected wave of pile body were analyzed from the point of view of time domain and frequency domain. The integrity of the system is evaluated, which provides a reference for the application of engineering field testing. The research shows that the low strain reflection wave method has obvious advantages in pile integrity detection and is suitable for testing different types of piles. However, there are still some problems in the detection technology that need to be further studied.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.16

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