带承台（梁）桩缺陷检测若干关键问题研究

发布时间：2018-01-06 00:28

本文关键词：带承台（梁）桩缺陷检测若干关键问题研究　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：低应变反射波法因其方便快捷且费用低廉的优势而在桩的完整性检测中得到广泛应用,但目前对桩身缺陷动态测试的研究还不完善,缺乏桩身缺陷各要素对低应变反射波法测试结果的影响的系统分析;另一方面,由于地震和滑坡等自然灾害、车船撞击等人为事故以及环境腐蚀等原因,使得带承台(梁)桩的检测评估成为一项重要课题,但现有检测方法存在很大不足。鉴于此,本文基于桩基振动理论研究桩身缺陷各要素对桩的动力响应的影响,并在此基础上提出一种带承台(梁)桩完整性检测的新方法。主要工作及成果如下:1.系统地分析了桩身缺陷尺寸效应,即缺陷长度和径向尺寸(对变模量缺陷而言即模量减小程度)对桩的低应变反射波曲线的影响,以及与缺陷位置、桩-土参数之间的关系,在此基础上,讨论了中间位置较长缺陷造成的信号叠加干涉现象及较短缺陷的可识别性与一系列桩-土参数及激振脉冲宽度之间的关系。2.采用径向圈层间的剪切复刚度传递法考虑施工扰动造成的桩周土的径向非均质性,通过考虑桩的横向惯性效应近似模拟大直径桩的三维波动效应,建立了大直径桩桩顶频域响应解析解和时域响应半解析解,据此研究了非均质土中大直径桩纵向振动特性,分析了桩身缺陷各要素对大直径桩低应变反射波曲线的影响,以及与桩的横向惯性效应、桩身参数及施工扰动效应的关系,最后,通过与实测低应变反射波曲线的对比验证了计算模型的合理性。3.针对带承台桩完整性检测存在的问题,提出了一种新的无损检测方法,即基于行波分解的泛频响函数法,将承台对桩顶的作用简化为粘弹性支承边界,将桩身某一截面作为检测截面,采用自行编制的波动分析程序求解检测截面位置处的泛频响函数,并通过虚拟输入半正弦脉冲的方式将泛频响函数所包含的信息转换到时域内,从理论上论证了检测方法的合理性,继而分析了桩-土参数及桩身缺陷各要素对泛频响函数及由此转换而来的时域响应曲线的影响。4.采用考虑土体竖向波动效应的三维轴对称模型建立桩周土的纵向振动控制方程并考虑施工扰动效应造成的土体的径向非均质性,采用一维杆件理论建立桩的纵向振动控制方程、Timoshenko梁理论建立桩顶连梁的振动控制方程,通过桩-梁之间的耦合条件求解得到单排高桩检测截面处的速度波和力波曲线,进而通过变换得到检测截面处的速度导纳和时域响应,论证了泛频响函数法的可行性,分析了桩-土参数及桩身缺陷的影响,以及与施工扰动效应的关系,最后论证了检测方法对既有结构物下大直径桩的适用性。5.基于三维轴对称模型建立了同时考虑桩周土和桩芯土成层性及径向非均质性的大直径管桩纵向振动频域响应解析解和时域响应半解析解,分析了桩芯土对大直径管桩纵向振动特性的影响、桩身缺陷的影响与桩芯土及土体径向非均质性的关系,在此基础上,研究了既有结构物下大直径管桩动力响应及桩身缺陷的检测问题。本文所做工作对处于打桩结束阶段的单桩及带承台(梁)桩的完整性检测具有重要意义。
[Abstract]:Low strain reflection Bofayinqi convenient and low cost advantages and is widely used in the integrity testing of piles, but the research on the dynamic testing of pile defects is not perfect, the lack of influence of each factor analysis system of pile defects on the test results of low strain reflection wave method; on the other hand, due to natural disasters the earthquake and landslide, travel impact such as the reason accidents and environmental corrosion, so the pile cap (beam) detection and evaluation has become an important issue, but the existing detection methods have some disadvantages. In view of this, the influence factors of pile vibration response defect theory research based on dynamic pile on the pile, and then based on a new cap (beam) method of pile integrity detection. The main work and results are as follows: 1.. Systematic analysis of the pile defect size effect, defect length and diameter to the size (the variable That is the degree of reduction of the modulus modulus defect) influence on pile low strain reflection wave curve, and the defect position, the relationship between pile and soil parameters. On this basis, the signal superposition caused by the middle position longer defects interference phenomenon and shorter defects can be identified with a series of parameters of soil and pile the excitation pulse width.2. relationship between the complex stiffness of radial transfer method considering the pile construction disturbance caused by the heterogeneity of the radial shear between the spheres, by considering transverse inertial effect of pile approximate 3D wave effect simulation of large diameter piles should be established, large diameter pile top frequency response analytical solution and semi analytical solution time response, based on the longitudinal vibration characteristics of large diameter pile in the heterogeneous soil, analyzed the influence factors of pile defects of large diameter pile low strain reflection wave curve, and the pile lateral inertia effect, Relationship between pile parameters and construction disturbance effect. Finally, through the comparison with the measured low strain reflection wave curves to verify the rationality of the calculation model of.3. with pile integrity detection problem, proposed a new nondestructive testing method, called generalized frequency response function method based on the decomposition of the traveling wave, the cap on the simplified effect of pile top for visco elastic support boundary, will pile a section as a detection section, using self-made pan wave analysis of frequency response function program to solve the position detection section, and through the virtual input half sine pulse of the information contained in the extensive frequency response function in time domain, theoretically the rationality of detection method, then analyzes the pile and time-domain parameters of soil and pile defects of each factor in the frequency response function and the conversion of the universal response effect of.4. curve by considering vertical wave The longitudinal vibration control equation of pile 3D axisymmetric model and consider the effect of radial soil caused by construction disturbance effect heterogeneity, using the one-dimensional longitudinal vibration theory of pile vibration control equation and control equation of Timoshenko beam is established based on the theory of beam on the top of the pile, by solving the coupling conditions between single pile beam rows of high pile detection section of velocity and stress wave curve, and then the response detection section and velocity admittance obtained by time-domain transform, proves the feasibility of generalized frequency response function method, analyzes the influence of pile body defect parameters of soil and pile, and the relationship with the construction disturbance effect, finally proves the detection method for the the existing structure of large diameter piles under the applicability of.5. 3D axisymmetric model was established based on considering the soil around the pile and soil layer of core and radial non vertical heterogeneity of large diameter pile In response to a semi analytical solution of analytical solution and time domain response analysis of the impact of vibration frequency, pile core soil on the longitudinal vibration characteristics of large diameter pile, effect of pile defect and pile soil and soil radial heterogeneity, on the basis of this research, the existing defect detection problem of large diameter pile and pile dynamic response structure. The work done in the end stage of single pile and pile with cap (beam) plays an important role in integrity testing of piles.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU473.16

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