基于数字散斑法对混凝土单轴受压裂缝发展过程的研究

Study on the Development Process of Uniaxial Compression Cracks in Concrete Based on Digital Speckle Method

摘要: 本文将三维数字散斑相关方法(Digital Image correlation, DIC)引入纳米混凝土变形测量当中，基于数字散斑技术对纳米混凝土在单轴受压过程中的全场位移和应变进行采集，分析混凝土在不同纳米材料掺量、不同受力阶段下应变云图的变化特征和变形参数的变化规律，并对比不同纳米掺量混凝土力与位移曲线。结果表明：纳米含量为1.5%的混凝土于纳米含量为1%的混凝土相比，其强度降低了15.7%。其降低原因可能是由于随着纳米含量的增加，纳米二氧化硅在分散时出现团聚的可能性增加，从而导致混凝土强度降低。数字散斑相关方法可有效观测纳米混凝土试件在变形前后应变演化趋势，从而对试件裂纹的扩展进行计算。混凝土受压过程中，发生的应变突变现象是因为混凝土局部破坏导致。混凝土破坏是由横向裂缝和纵向裂缝共同作用。

Abstract: In this paper, a three-dimensional digital speckle correlation (DIC) method is introduced into the measurement of nano-concrete deformation. Based on digital speckle technology, the full-field displacement and strain of nano-concrete during uniaxial compression are collected and analyzed. Analyze the changing characteristics of the strain cloud diagram and the changing rules of the deformation parameters of the concrete in different nano-material dosages and different stress stages, and compare the force and displacement curves of different nano-concrete concretes. The results show that the strength of concrete with a nano-content of 1.5% is reduced by 15.7% compared to concrete with a nano-content of 1%. The reason for this decrease may be that as the nano-content increases, the possibility of agglomeration of nano-silica during dispersion increases, resulting in a decrease in the strength of concrete. The digital speckle correlation method can effectively observe the strain evolution trend of nano-concrete specimens before and after deformation, thereby calculating the crack propagation of the specimen. During the compression of concrete, the sudden change of strain is caused by the local failure of concrete. Concrete failure is caused by a combination of lateral and longitudinal cracks.