基于细观结构特征的混凝土材料动态力学性能、破损机制及数值试验研究

The dynamic damage of concrete-sort geotechnical materials mainly display in energy accumulation of internal defects and micro-crack propagation, coalescence and failure till the global instability process, while X-ray CT technique is an effective observation method for detecting non-destructively the internal meso-damage process of concrete.By using integrally the sensitivity feature of acoustic emission location technology and the vivacity computerized tomography technology ,the fine test on damage process of concrete under dynamic loading is realized. Based on CT experiment data of concrete, a set of analysis method of meso-crack indentification and evolution process is established based on CT image analysis. So the crack morphology and evolution process of quantitative analysis and description is implemented.The influence of the dynamic mechanical properties of concrete and strain rate effect under dynamic loading condition on the damage mechanism are researched by using energy evolution, According to the results of fine test, the 3-D reconstruction model of concrete specimen is numerically simulated with the developed dynamic damage constitutive relationship.Then, the dynamic CT experiment results of concrete and the results of numerical simulation are compared and analyzed , which check the numerical experiment model. So the study will provide mechanical basis for the improvement of experiment design. therefore a new way is developed for the solution of concrete meso dynamic damage mechanism research and provides the basis for major engineering dynamic catastrophe prediction research.

混凝土类岩土材料的动态破损主要表现在材料内部初始缺陷能量积聚，微裂纹不断萌生，扩展、贯通直至整体失稳的过程，而X射线CT技术是无损探测混凝土内部细观破损过程的有效手段。本项目运用CT技术的直观性以及声发射技术的灵敏性实现对动态荷载条件下混凝土材料破损过程的精细测试，并以混凝土CT试验数据为基础，建立一套基于CT图像分析的混凝土细观裂纹识别、裂纹演化过程的分析方法，实现对裂纹形态和演化过程定量分析和描述。利用能量演化规律研究混凝土动态力学性能以及动态荷载条件下应变率效应对破损机制的影响。并在精细测试结果上，利用建立的混凝土动损伤本构关系对三维重建模型进行细观数值试验研究，并将数值试验结果与动态CT试验结果进行比较从而校正数值试验模型，为改进试验设计提供力学依据，开辟凝土细观动态破损机理研究的新途径，为重大工程动力灾变预测研究提供依据。

混凝土类岩土材料的动态破损主要表现在材料内部初始缺陷能量积聚，微裂纹不断萌生，扩展、贯通直至整体失稳的过程，而X射线CT技术是无损探测混凝土内部细观破损过程的有效手段。本项目运用CT技术的直观性以及声发射技术的灵敏性实现对动态荷载条件下混凝土材料破损过程的精细测试，并以混凝土CT试验数据为基础，建立一套基于CT图像分析的混凝土细观裂纹识别、裂纹演化过程的分析方法，实现对裂纹形态和演化过程定量分析和描述。利用能量演化规律研究混凝土动态力学性能。并在精细测试结果上，利用建立的混凝土动损伤本构关系对三维数值模型进行细观数值试验研究，为改进试验设计提供力学依据，开辟凝土细观动态破损机理研究的新途径，为重大工程动力灾变预测研究提供依据。