【作者】 张晓飞；

【导师】 陈尧隆； 李守义；

【作者基本信息】 西安理工大学 ， 水工结构工程， 2009， 博士

【摘要】 大体积混凝土结构温度场和温度应力的分析、温度控制和防止裂缝的措施是设计和施工中的重要课题,进行大体积混凝土结构温度场和应力场仿真计算研究具有重要的实际意义。而温度应力的仿真计算与大体积混凝土结构的结构形式、气候条件、施工过程、材料特性以及运行条件等多种因素有密切的关系。“内降外保”是大体积混凝土结构施工中普遍采用的一种温控措施,对于高温季节施工的部位,或者坝体需要满足接缝灌浆的温度要求时,往往采取通水冷却措施,以降低坝体内部的最高温度；对于低温季节施工的部位,或坝体遭遇寒潮时,往往需要采取表面保温措施,以减小坝体表面的最大温差,从而减小坝体表面的拉应力。因此,对于冷却水管和表面保温计算方法的研究,具有重要的实际应用价值。本文根据热传导理论及有限元方法,建立模拟施工过程仿真计算的数学模型,提出了在混凝土坝冷却水管布置区采用冷却水管子结构有限元法,在冷却水管布置区以外采用三维有限元浮动网格法,并着重对三维有限元网格浮动法与冷却水管子结构的耦合方法进行了研究；同时从热量平衡原理出发,推导了直接以导热系数、表面散热系数和热量为热传导方程基本参数的温度场有限元方程,使之能够更合理地反映由多种热学性能差异较大的材料组成的复合结构的温度场,也系统地研究了大体积混凝土结构表面保温所采用的导热系数法、导温系数法和等效厚度法。其次,针对大体积混凝土结构分层分块跳仓浇筑以增大散热面积和减小浇筑块尺寸这一实际情况,提出了采用Ansys软件创建有限元模型,并采用自行开发研制的基于Fortran语言的温控仿真程序进行温度场和温度应力仿真计算,Sufer软件进行后处理的方法,实现了对任意复杂结构的温控仿真计算；最后针对大体积混凝土结构温控计算过程中,因室内试验参数很难反应施工现场混凝土的真实性能这一实际问题,提出了采用三维有限元浮动网格法和可变容差法对混凝土热学参数进行反分析,以得到反映混凝土真实热学性能参数的方法,可用于预测、指导工程的施工。本论文的研究成果,可以方便、快速、准确地计算埋设冷却水管、采取表面保温和跳仓浇筑条件下大体积混凝土结构的温度场和温度应力。同时结合施工现场得到的实测温度数据,通过反分析以确定混凝土的热力学参数。为大体积混凝土结构温度场和温度应力计算提供了科学依据,也为大体积混凝土温度控制的进一步研究提供理论基础。更多还原

【Abstract】 The temperature and thermal stress fields analysis, the temperature control and crack control measures of the mass concrete structure are all important study subject in the design and construction, and the study on simulation calculations of the mass concrete structure temperature field and thermal stress field is of great practical significance. The thermal stress simulation computation is related with many factors, such as structural shape, the climate condition, construction process, material property and operation condition."Internal cooling and external heat insulation" is a common temperature control measure in the mass concrete construction. For the parts cast in high temperature season, or there being temperature requirement for the dam joint grouting, the water cooling measure is always adopted to reduce the peak temperature inside the dam, while for the parts cast in low temperature season or the dam encountering the cold wave, the superficial heat insulation measure is made to weaken the maximum temperature difference of dam surface, thus reducing the surface tensile stress. Therefore, the research on cooling pipe and superficial heat insulation are of great practical value. According to the heat conduction theory, mathematic model which can simulate the construction process is established, and it is posed that in the cooling areas, the cooling pipe substructure finite element method is used, while in other areas, the 3-D finite element relocating mesh method is utilized in the paper, and the study of coupling of substructure method and the 3-D finite element relocating mesh method is emphasized. Based on the heat budget theory, the temperature field finite element equation is deduced with thermal coefficient of conduction, surface thermal diffusivity and heat quality as basic parameters, so that it can reasonablely reflect the temperature field of composite structure composed of many materials of great different thermal properties. At the same time, the thermal coefficient of conduction method, the thermal diffusivity method and equivalent thickness method are all studyed.Regarding the actual situation that mass concrete is cast in layers and block to expand the dissipation areas and lessen the cast block size, the finite element model is established by Ansys software and it is posed to use the Fortran temperature control simulation programme to calculation the temperature field and thermal stress, then use the Surfer software to carry the postprocessing, thus making simulation calculation of any complex structure true. In the end, considering the problem that the indoor concrete test parameters can hardly reflect the ture property of the concrete in construction site, it is proposed that the 3-D finite element relocating mesh method and the flexible tolerance method are combined to inverse analyze the concrete thermal parameters, so as to get the ture concrete thermal property parameter for predicting and instructing the following construction.Through the research above, we can calculate the temperature field and thermal stress of the mass concrete structure with water cooling measure or surface heat insulation or by sequence placement, at the same time, the ture concrete thermal parameters can be defined by the observed temperature data in inverse analysis method, which provide the scientific references for the temperature field and thermal stress calculation of the mass concrete structure, and provide theory for the father study on the mass concrete temperature control.更多还原