【作者】 王振波；

【导师】 徐道远；

【作者基本信息】 河海大学 ， 水工结构工程， 2001， 博士

【摘要】 混凝土结构、尤其是大体积混凝土结构在浇筑成形的过程中，由于受到内外温度变化的影响从而使混凝土体内或表面形成细微裂隙等缺陷，研究细微裂缝（微裂纹）的形成与发展在混凝土材料学中是一项十分重要的课题。本文在总结前人研究成果的基础上，从混凝土材料组成的微细观角度出发，应用混凝土断裂力学和损伤力学理论对混凝土材料在温度荷载作用下的损伤问题进行了理论与试验研究，提出了混凝土温度损伤模型，并导出了混凝土温度损伤演变方程，最后用损伤有限元对拱型结构进行了数值计算，论文的具体内容如下： 1．运用仿真技术对大体积混凝土结构进行了不考虑损伤状态下的温度场及应力场的仿真计算。计算过程中综合考虑了混凝土结构内部温度的变化，环境温度的变化，施工顺序，浇筑时间以及材料弹性模量的变化，徐变特征，自身体积等因素，同时指出了仿真计算中存在的问题与不足之处。 2．提出了底板类大体积混凝土结构温度场及温度应力场的分层计算方法，建立了分层计算物理与数字模型，推导了数学计算式，并给出了底板类大体积混凝土温度场计算的解析解，从而为初步估算底板类大体积混凝土结构的温度场及温度应力提供了方便适用的手段。 3．对机械荷载作用下研究损伤问题的思路与研究方法进行了探讨，总结了机械荷载作用下混凝土损伤发展的特性，提出了机械荷载作用下所建立的损伤模型用于研究温度损伤时存在的不足之处。 4．进行了水泥砂浆，夹石及混凝土试件温度损伤试验研究，分析了混凝土在升温与降温过程中损伤随温差的变化规律。研究结果表明：混凝土内界面是最薄弱的环节，损伤首先在界面上发生，然后向水泥砂浆中发展；且降温时产生的损伤累积要比升温时产生的损伤累积大，但升、降温对于混凝土材料都是不利的，均会引起混凝土材料的力学性能劣化，同时指出影响主要因素是温差。 5．在试验的基础上对混凝土损伤机理进行了分析，由此提出了混凝土温度损伤模型。该模型是从混凝土组成的微细观角度出发，简化为水泥砂浆包围骨料的平面问题，微裂纹首先在界面上产生然后向水泥砂浆中延伸。微裂缝的形成与发展仍然是由温度应力造成的，但此温度应力应是考虑损伤行为的应力，据此，文中导出了反映初始损伤、材料强度、弹性模量以及断裂能的温度损伤演变方程。 6采用损伤有限元对拱型结构进行了损伤场及考虑损伤行为应力场的计算。损伤有限元计算是在已有的断裂一损伤有限元的程序中加入本文给出的温度损伤演变方程，以实现了温度损伤及考虑损伤后应力场的计算。更多还原

【Abstract】 When mass concrete forms, defects will produce such as some micro crack resulting from the different temperature between the surface and the inside. How this micro crack forms and develops is a very important subject hi Materials. Focusing on the micro construction of concrete materials, some research has been done. Based on the former accomplishment and two theories: Fraction Mechanics and Damage Mechanics, the thermal damage model is established. The temperature damage developing equation is presented, as well as the calculation of arch construction. The main contents are as follows:1. Influence of the temperature field and stress field is ignored but some other factors are considered such as temperature difference between the surface and inside of the concrete, circumstance temperature, work sequence, shaping period, elasticity modulus, the volume etc. And the emulation technology is applied to calculating the construction of the concrete. The deficiency in emulation calculation is also mentioned.2. How to estimate roughly in lamination temperature field and temperature stress field of mass concrete of base-plate are presented. Physical and mathematical model of calculation in lamination is established. Calculation formula is given and so is the result.3. The ways to study damage under mechanical strain are systematically discussed. The character of damage development under mechanical strain is explained. The deficiency of the damage model is pointed out too.4. The temperature damage experiment about mixture of cements, stones and concrete is carried out for the first time. Principle that the damage changed with the temperature is analyzed. The results indicate the inner interface is the weakest one. First, the damage accumulates at the boundary, then it spreads toward the cements. The damage occurred at temperature increasing. However, both of them are not beneficial, for they will reduce the material’s mechanics ability. So the temperature difference is the main factor.5.The damage principle of the concrete is analyzed according to the experiments, and the damage temperature model is put forward. In the view of the concrete’s micro construction, it can conclude that the boundary is the weakest. Minute crack occurs firstly at the boundary, and then it spread toward the cements, which are produced by thermal stress. But thermal stress can’t be calculated without damage. And then it provided in this article the equation of the elementary damage, material intensity, elasticity modulus and temperature evolvement of rupture energy.6. Damage finite element, which can be calculated by rupture-damage finite element program, is applied to arch construction to calculate damage field and stress field with damage character considered, hi the program temperature damage developing equation is presented.更多还原