【作者】 赖碧涛；

【导师】 李彰明；

【作者基本信息】 广东工业大学 ， 岩土工程， 2006， 硕士

【摘要】 预应力管桩是预制混凝土桩体和岩土体共同作用的系统,影响其工作性能的因素很多,破坏模式复杂,进行桩基概率极限状态设计与模糊概率极限状态设计方法的研究是一项具有重要意义而较艰巨的任务和工作。 本文分析了预应力管桩的特点、适用的地质条件,并对现行规范在计算预应力管桩的竖向承载力所采用的安全系数法的特点与不足进行了讨论分析。在此基础上,采用数理统计的方法,结合桩的荷载传递机理,应用高应变法测桩的大量数据作为统计的基础,对现行预应力管桩桩规范中有关预制桩的竖向荷载的计算方法及公式进行分析和改进。 一方面,本文应用了可靠性理论分析的方法,确定了预应力管桩的可靠度指标β,并提出了预应力管桩竖向承载力的总抗力分项系数,侧摩阻力分项系数和桩端阻力分项系数。另一方面,本文将模糊可靠性分析方法引入及应用于该类问题,确定了预应力管桩的模糊可靠度指标(?),并在此基础上提出了预应力管桩竖向承载力的总抗力分项系数,侧摩阻力分项系数和桩端阻力分项系数。同时建立了预应力管桩的竖向承载力的计算表达式,为今后规范的修正和同类型桩的单桩竖向承载力的设计提供了参考。最后,本文利用具有代表性的数根混凝土预应力管桩的静荷载试验结果,与本文基于可靠性理论建立的预应力管桩竖向承载力理论公式、基于模糊可靠性理论建立的竖向承载力理论公式、规范公式的结果进行了比较、检验;结果表明,本文的理论结果与实测结果较为接近。更多还原

【Abstract】 Probabilistic models and fuzzy set models describe different aspects of uncertainty. Probabilistic models primarily describe random variability. In Geotechnical engineering system safety of pre-stressed concrete tube piles, ultimate bearing capacity of piles is variability with soil layers and parameters of soil layers, material properties, geometrical dimensions, and loads. In other hand, fuzzy set models of uncertainty primarily describe vagueness, such as vagueness in the definition of safety.Firstly, reviewing the codes we use nowadays to calculate the ultimate bearing capacity of pre-stressed tube pile, though relative simple and convenient, many flaws are included and the results calculated by the codes are so rough compared to the load test results. The major object of this paper is to analyze the influence impacting the ultimate bearing capacity by analyzing the data collected from experiments of high strain dynamic testing of piles. Another main object is to establish formulations, which discribe the ultimate bearing capacity of pre-stressed tube piles more accurate and accessible on practical conditions than the code used nowadays.Secondly, a typical practical project in which a large number of pre-stressed concrete tube piles were use as a main foundation is introduced in detail. Furthermore, specific data collected from the project is analyzed to deduce the reliability index and fuzzy reliability index which are used to calculate the partial index in an ultimate bearing capacity formulation. Furthermore, a set of partial index depended on the probability theory and a set of partial index depended on the fuzzy probability theory are successfully deduced. Therefore, two formulations based on the two new sets of partial index are established in this thesis.Finally, in order to evaluate the two new established formulations, three typical piles are chosen to justify them. The results is that the formulation established by the fuzzy probability is the most accessible to the result of the load test of the three, and the formulation established by the probability takes the second place, the three place isthe method recommended by the code.These two formulations referred above will enable the significance of calculating the ultimate bearing capacity of pre-stressed concrete tube piles, which will lead to economical merits and offer reference to the establishment of new codes.更多还原