水泥基材料受冻破坏下的损伤行为研究

发布时间：2018-09-09 19:25

【摘要】：在中国西部地区,由于高寒严酷的气候条件,受冻破坏成为水泥基材料损伤的重要原因之一。本文通过理论方法对受冻破坏过程中物理变化进行阐述,对材料在冻融循环过程中的损伤程度进行定量化分析,从而提高其抵抗冻融破坏的能力。饱水度和体积模量是影响水泥基材料变形的两个重要参数。本文通过表征材料孔隙内的水分的“毛细管凝结”,“吸附和脱附”以及“墨水瓶效应”等现象,建立起材料的水分分布模型。此外,基于多层夹杂模型对一定骨料粒径分布的水泥基材料的力学性质进行表征。结果表明多层夹杂模型对材料的体积模量的表征有很好的适用性。本文对材料在完全饱和的状态下的冻融循环过程进行了模拟。发现当材料完全饱水时,由于水转化为冰时,孔隙内物质的密度会发生变化,使材料产生十分明显的变形。这一变形会使材料自身发生损伤开裂。材料处于不饱水时,饱水度的大小会直接影响冻融过程中的变形。在材料含有气泡时,气泡作为低温泵对水泥基材料的内部变化产生显著的影响。同时结晶压和静水压也被应用于含有气泡的水泥基材料的分析中。本文对水泥基材料中不含盐的条件下发生表面剥落的情况进行了阐述。一般认为,盐的作用会使水泥基材料在冻融过程中产生表面剥落。而通过多孔介质力学的理论模拟发现,即使不含盐,在温度降低时,材料的表面会迅速结冰,阻碍了孔溶液流动,降低了材料的渗透性,材料表面因此也会形成较大的拉伸力,促使材料表面剥落。最后,通过应变能和开裂能相等计算材料的开裂面积。基于此对材料的损伤程度进行定量化表征。
[Abstract]:In western China, freezing damage has become one of the important reasons of cement material damage due to the severe climate conditions of alpine and cold. In this paper, the physical changes in the process of freeze-thaw damage are described by theoretical method, and the damage degree of materials during freeze-thaw cycle is analyzed quantitatively, so as to improve the ability of resisting freeze-thaw damage. Saturation degree and bulk modulus are two important parameters that affect the deformation of cement based materials. In this paper, the water distribution model of the material is established through the phenomena of "capillary condensation", "adsorption and desorption" and "ink bottle effect" which characterize the moisture in the pores of the materials. In addition, the mechanical properties of cement-based materials with certain aggregate size distribution were characterized based on multi-layer inclusion model. The results show that the multilayer inclusion model is suitable for the characterization of bulk modulus of materials. In this paper, the freezing and thawing process of materials at full saturation is simulated. It is found that when the material is fully saturated, the density of the material in the pore will change when the water is converted to ice, and the material will be deformed obviously. This deformation will cause damage and cracking of the material itself. When the material is under water, the degree of saturation will directly affect the deformation of freeze-thaw process. When the material contains bubbles, the bubble as a cryogenic pump has a significant effect on the internal changes of cement-based materials. At the same time, crystallization pressure and hydrostatic pressure are also used in the analysis of cement-based materials containing bubbles. In this paper, the surface spalling of cement-based materials without salt is described. It is generally believed that the effect of salt causes the surface spalling of cement-based materials during freezing and thawing. Through the theoretical simulation of the mechanics of porous media, it is found that even without salt, the surface of the material will freeze rapidly when the temperature is lowered, which hinders the flow of the pore solution, reduces the permeability of the material, and thus forms a large tensile force on the surface of the material. Causes the material surface to flake off. Finally, the crack area of the material is calculated by strain energy and crack energy. Based on this, the damage degree of the material was quantitatively characterized.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

【相似文献】