【作者】 周圣斌；

【导师】 侯建国；

【作者基本信息】 武汉大学 ， 结构工程， 2004， 硕士

【摘要】 我国现行电力行业标准SD 145-85《混凝土拱坝设计规范》采用容许应力法进行设计，这种设计方法忽视了作用和抗力的随机性，以单一的安全系数衡量拱坝的安全，同时安全系数的概念也不够明确，带有人为的因素。采用以可靠度理论为基础的极限状态设计法可以克服以上缺点，更全面的考虑影响结构可靠性各因素的变异性，用结构的失效概率来衡量结构的可靠度水平，根据工程结构的不同特点来适当的划分和选择安全级别，合理的选择各个分项系数，以便更好的处理结构安全和经济之间的矛盾，为实现优化设计，在安全与经济之间选择最佳平衡创造了条件。 目前，在水利水电规划设计总院的主持下，SD 145-85正在按GB 50199-94《水利水电工程结构可靠度设计统一标准》关于概率极限状态设计法的有关规定进行修编。国家电力公司成都勘测设计研究院为SD 145-85修编的主编单位，并于2002年1月提出了《拱坝规范修编专题报告》。然而《拱坝规范修编专题报告》在拱坝混凝土强度标准值、分项系数设计表达式中各分项系数的取值和坝体可靠指标计算方法上存在一些不足之处或不够完善的地方。基于此，笔者广泛的搜集国内外相关资料和研究成果，在这些方面开展了一系列研究工作，其主要研究成果如下： (1) 在规范的修编过程中，首先要确定的是拱坝混凝土强度等级的定义。现行水工方面的有关规范对拱坝混凝土强度等级的确定原则是不一致的。针对这一情况，本文从混凝土试件标准尺寸，混凝土强度等级保证率提高到95％对材料用量、抽样检验错判概率和拱坝混凝土耐久性的影响，龄期的确定这三个方面的讨论了拱坝混凝土强度等级与DL／T 5057-1996相协调的可行性。认为这种做法是值得推荐的。 (2) 根据已搜集到的国内外拱坝规范、混凝土强度试验和相关文献，通过分析比较，提出了能反映拱坝混凝土强度特性的强度标准值取值方案；按照GB 50199-94原则，给出了极限状态设计表达式中各分项系数的取值方案，通过计算表明，该极限状态设计表达式所包含的安全度水平与SD 145-85的容许应力设计法的设计表达式所包含的安全度水平具有较好的一致性。 (3) 通过对现有拱坝坝体可靠指标计算方法的比较研究，发现这些计算方法在不同程度上都存在一些缺陷或不足之处。并提出了基于人工神经网络和蒙特卡罗法的拱坝坝体可靠指标计算方法，在计算过程中，探讨了在设计验算点未知时人工神经网络输入参数的选择，通过计算实例表明，本文提出的输入参数选择方法能使神经网络有效的模拟设计验算点附近的功能函数，计算结果精度较高。更多还原

【Abstract】 The power system standard in China SD 145-85 Design Code for Concrete Arch Dams adopt the allowable stress method, this method ignored the randomicity of action and resistance, adopt single safety factor to measure the safety of arch dams, at the same time conception of safety factor is not specific enough, and have human element factor, adopting limit state design method based on the theory of reliability can conquer the aforesaid disadvantage, comprehensively considered each factor’s variability that may effect the reliability of structure, use structural failure probability to measure structural level of reliability, based on different trait of structure to sort and choose safety grade, choose each partial factors reasonably, deal well with the contradiction between structural safety and economy, to realize optimize design, create the condition to choose the best balance between safety and economy.Nowadays, under the support of hydraulic and hydroelectric planning design institute, SD145-85 is being revised according to the related provision of probability ultimate limit state design method, stated in GB 50199-94 United criterion of reliability design in hydraulic and hydroelectric engineering structure. National electric power corporation Chengdu reconnaissance design institute is editor in chief of SD 145-85, moreover Special reports on arch dams was put forward in January 2002. However there are some shortages about standard value of concrete strength, value of partial factors in partial factor design expression and reliability index of arch dams in Special reports on arch dams. According to these reasons, the author collected relative data of home and abroad and carried a series of work on these assets. The results as following:(1) During the revising course of the code, the definition of arch dams concrete strength class must be determined firstly. The determining principle of arch dams concrete strength class disaccord with each other in the related codes of current hydraulic engineering. Aim at this situation, the author discussed the feasibility of arch dams concrete strength class assort with DL/T 5057-1996 code, which focused on standard size of concrete specimen, the infection on dosage of material, the miss judged probability spot check and arch dams concrete wear of elevating concrete strength class assuring rate to 95%, determination curing duration three aspects in this paper. And insisted that it’s worth to recommending to take this scheme.(2) Based on the collected arch dams code home and abroad, concrete strength test and other related references, the author put forward a strength standard value scheme that can reflect arch dams concrete strength characteristics. According to principle of GB 50199-94 code, the author gave scheme of all partial factors of ultimate state design expression. The author’s calculation indicated that safety level contained by this ultimate state design expression is in good accord with that of allowable stress design expressions in SD 145-85 code.(3) Through comparatively study the current arch dams calculation method of the reliability index found that these methods exist disfigurement and insufficiency in different degree. And given arch dams calculation method of the reliability index based on artificial nerve network and Monte Carlo method, during the course of calculation, discussed how to choose the artificial nerve network ’s input parameter under the design checking point is not given, the practical calculation indicated, the choose input parameter method that is given in this paper can simulate the function neighborhood the design checking point, so can advance calculation precision.更多还原