基于模糊综合评判法超声波测桩评价研究

发布时间：2018-07-21 12:41

【摘要】：桩基础历史悠久,现如今其广泛应用于各种建筑行业,属隐蔽工程,同时桩基础的质量直接决定了建筑优劣,从而其影响着人民的生命和财产安全,因此桩基础的试验和检验是必不可少。对于超长混凝土灌注桩来说,需要检测桩身承载力和完整性。桩身完整性检测有多种方法,其中声波透射法具有检测全面优点,并且其在桩检方法中具有重要的代表性,其在业内应用较多,但其评判标准还不够全面,并且其无法评判桩基承载力。因此需要进一步研究并提高。本文系统的研究了声波透射法的原理,对其原理和历史尽心剖析,详细评述了混凝土的各个声学参数与混凝土质量的关系,从而确立声学参数和桩身缺陷之间的存在的关系。综合探讨基桩检测数据和对应的评判结果之间存在的关系,确定不同的检测数据对应的是那种缺陷,重点研究了桩身缺陷的评判方法,不同的桩基缺陷所对应的桩基承载性能,以及声测管管斜修正等问题。研究结果表明,现有的桩基评判方法较为单一,通常只以其中一个或两个声学参数对桩基进行评判,无法考虑多种声学参数的相互共同的结果对桩基质量进行评判,对于桩基承载性能也只能通过另一种试验方法来确定。为了丰富、完善现有的评判方法,本文会提出新桩基质量评判方法,同时对存在缺陷的桩基承载性能进行研究。首先,本文基于有限元法理论,通过有限元软件Midas GTS来模拟不同桩身缺陷的桩基,并且模拟相同缺陷下,从而计算其在不同缺陷位置桩基的竖向承载能力。如此找出厚砂层这一地质下,超长灌注桩的承载力和各种缺陷之间关系；其次,本文运用模糊数学理论,基于原有判据提出模糊综合评判法这一科学方法,将声速、波幅、频率和PSD值这四个相互影响的声学参数综合考虑,从而对桩基质量进行评判。利用模糊综合评判法评判基桩质量时,通过统计学中的“F分布法”确立各评价指标相对于桩基评价的梯形和半梯形隶属度函数,然后采用模糊层次分析法计算各评价指标的客观、合理的权重值,最后通过各测点模糊运算,得出一个综合评判的结果。为了验证本文所提出的模糊综合评判法的科学、实用性,并且优越于原有的判据,本文已通过分析大量的工程实例对其进行验证。从本文结果来看,本文的模糊综合评判法合理、科学、可行。模糊综合评判法与模糊层次分析法的相结合,其综合考虑了多个重要的声学参数判据,相比于其他评判方法,该方法多评判的结果具有客观性,更加真实、更加完善,并且可以取得了良好效果。
[Abstract]:Pile foundation has a long history, now it is widely used in various construction industries, it is a hidden project, and the quality of pile foundation directly determines the quality of the building, thus affecting the lives and property safety of the people. Therefore, it is necessary to test and test the pile foundation. For super long concrete cast-in-place pile, the bearing capacity and integrity of pile body should be tested. There are many methods for pile integrity detection, among which the acoustic transmission method has the advantages of comprehensive detection, and it has important representativeness in the pile inspection method, and it is widely used in the industry, but its evaluation standard is not comprehensive enough. And it can not judge the bearing capacity of pile foundation. Therefore, further research and improvement are needed. In this paper, the principle of acoustic transmission method is systematically studied, and its principle and history are analyzed. The relationship between each acoustic parameter of concrete and the quality of concrete is discussed in detail, so as to establish the relationship between acoustic parameter and defect of pile body. This paper comprehensively discusses the relationship between the testing data of foundation pile and the corresponding evaluation result, and determines that the defect corresponding to different test data is the kind of defect. The evaluation method of pile body defect and the bearing capacity of pile foundation corresponding to different pile foundation defect are studied emphatically. And sound measurement tube oblique correction and other issues. The results show that the existing methods of pile foundation evaluation are relatively simple, and usually only one or two acoustic parameters are used to judge the pile foundation, and the quality of pile foundation can not be judged by considering the common results of various acoustic parameters. The bearing capacity of pile foundation can only be determined by another test method. In order to enrich and improve the existing evaluation methods, a new method for evaluating the quality of pile foundation is put forward in this paper, and the bearing capacity of the pile foundation with defects is also studied. Firstly, based on the theory of finite element method, the finite element software Midas GTS is used to simulate the pile foundation with different defects, and the vertical bearing capacity of the pile foundation is calculated under the same defect. In this way, the relationship between bearing capacity and various defects of super-long cast-in-place pile is found under the geological condition of thick sand bed. Secondly, this paper puts forward the scientific method of fuzzy comprehensive evaluation method based on the original criterion by using the theory of fuzzy mathematics to make the sound velocity and wave amplitude. The four acoustical parameters of frequency and PSD are considered synthetically to judge the quality of pile foundation. When the quality of foundation pile is evaluated by fuzzy comprehensive evaluation method, the membership functions of trapezoid and semi-trapezoidal membership degree of each evaluation index relative to pile foundation evaluation are established by "F distribution method" in statistics. Then the objective and reasonable weight value of each evaluation index is calculated by using fuzzy analytic hierarchy process. Finally, a comprehensive evaluation result is obtained by fuzzy operation of each measuring point. In order to verify the science and practicability of the fuzzy comprehensive evaluation method proposed in this paper, and it is superior to the original criterion, this paper has verified it by analyzing a large number of engineering examples. From the results of this paper, the fuzzy comprehensive evaluation method is reasonable, scientific and feasible. The combination of fuzzy comprehensive evaluation method and fuzzy analytic hierarchy process (FAHP) takes into account several important criteria of acoustic parameters. Compared with other evaluation methods, the results of this method are more objective, more real and more perfect. And can achieve good results.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU473.16

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