水泥基材料内部非均匀应力/应变的表征与模拟及其对裂缝形成与扩展的影响

The internal strain/stress caused by the external loading and self volume deformation is the primary reason for the cracking in cement based materials. However, due to the non-uniform and timeliness characteristics of cement based materials, the distribution of internal strain/stress is also non-uniform and changes with time; further, the internal strain/stress is influenced by the pre-embedded sensors. The previous studies mainly illustrated the influence of internal strain/stress on the cracking in cement based materials from a macro level, and the non-uniform and local strain/stress was seldom investigated. On the basis of the previous investigations about the internal non-uniform volume deformation by applying digital image correlation (DIC) method, the applicant proposed to use the numerical modeling combined with DIC method to analyze the non-uniform strain/stress and illustrate its influence on the formation and development of cracks in cement based materials. Lattice model will be used to simulate the multi-scale structure and internal strain/stress in cement based materials under different external conditions; meanwhile, based on the analysis on the physical properties of cement paste at early age, the propagation principle of cracks in cement based materials will be established. By combined with the non-uniform deformation data derived from DIC method, the relationship among the external conditions, material compositions, internal stress/strain and cracks in cement based materials will be established in order to provide the theoretical guidance for reducing the cracking in cement based materials.

外界荷载和自身体积变形在水泥基材料内部所引起的应力/应变是造成其开裂的根本原因，然而由于水泥基材料具有非均质性、时效性等特点，其内部应力/应变呈现非均匀性分布、随时间变化且易受外加传感器影响。现有研究多从宏观层次阐述水泥基材料内部应力/应变对开裂的影响，缺乏对其非均匀性、局部性的研究。在采用数字图像相关法（DIC）研究水泥基材料内部非均匀变形等前期工作基础上，申请人提出通过数值建模结合DIC技术，研究水泥基材料内部的非均匀应力/应变，探讨其对裂缝形成和扩展的影响。拟采用Lattice模型对水泥基材料的多尺度结构及外界条件下其内部的应力/应变进行模拟；同时通过对早期浆体的物理性质进行分析，建立水泥基材料中裂缝的扩展准则。结合DIC非均匀变形的数据，建立外界条件、材料组成、水泥基材料内部应力/应变和裂缝之间的关系，为减少水泥基材料的开裂提供理论指导。