基于微细观特性的道路透水混凝土裂缝演变规律和破坏机理研究

To date, the researches about failure mechanism of road pervious concrete are mainly based on the framework of phenomenological theory, which cannot reflect the essence of failure mechanism. Therefore, the micro- and meso-test and numerical simulation are applied to explore the essence of crack initiation, propagation, penetration, and failure of pervious concrete: The meso-damage process of pervious concrete under uniaxial compression is scanned by X-ray CT. Based on the meso-test data, the meso-crack was identified, and the evolution process is described quantitatively. In addition, the damage constitutive model of pervious concrete is also developed. PFC3D is used to achieve 3D reconstruction and simulate the uniaxial compression of pervious concrete. The meso-mechanical properties of the failure process in pervious concrete are studied. In terms of the principle of energy dissipation, the energy evolution of pervious concrete under uniaxial compression is revealed. After that, the influence of micro- and meso-characteristics of aggregate, interfacial transition zone, void and cement mortar on fracture propagation, meso-mechanical reaction and energy evolution is in-depth studied. Based on the results, the evolution law and failure mechanism of cracks in pervious concrete are discovered. The research results are expected to provide theoretical reference and technical support for the design, development and application of high strength pervious concrete.

目前关于道路透水混凝土破坏机理的研究主要建立在宏观唯象分析基础上，缺乏对破坏机理内在本质的深刻描述。本项目基于微细观测试技术和数值模拟手段，对透水混凝土裂缝的萌生、扩展、贯通、以及最后失稳破坏实质进行探索：采用X射线CT技术，实现对细观裂缝的识别和演化过程的定量分析和描述，建立透水混凝土损伤本构模型；通过PFC3D平台的透水混凝土三维重构和单轴压缩试验仿真，研究破坏过程中的细观力学特性；利用能量耗散原理，揭示透水混凝土破坏过程中能量演化规律；基于此，深入研究集料、界面过渡区、空隙和水泥胶浆的微细观特性对透水混凝土破坏过程中裂缝扩展、细观力学反应和能量演化的影响。综合上述成果，揭示透水混凝土裂缝演变规律和破坏机理，研究成果将有望为高强透水混凝土的设计、开发和应用提供理论参考和技术支持。

目前关于道路透水混凝土破坏机理的研究主要建立在宏观唯象分析基础上，缺乏对破坏机理内在本质的深刻描述。因此，通过室内试验、数字图像处理和离散元数值模拟多手段研究方法，多角度研究透水混凝土的细观结构特性和力学破坏机理：基于数字图像处理技术，重点分析了透水混凝土内部空隙和集料分布特性。通过室内透水混凝土单轴抗压强度试验，得到其应力-应变全曲线。结合室内透水混凝土开裂过程观测和应力-应变全曲线，分析透水混凝土破坏形态，并建立透水混凝土单轴抗压本构模型。采用离散元软件生成透水混凝土三维虚拟试件，采用椭球体描述粗集料颗粒的三维不规则形状进行单轴抗压强度数值模拟。以室内单轴抗压强度应力-应变曲线为依据，进行参数校验，结果表明离散元数值模拟结果与室内试验具有较好的一致性。基于数值模拟试验，从透水混凝土强度、内部颗粒分布、力链分布、接触点数量和接触力分布出发，研究集料组成、集料形状和水泥胶浆粘结强度对透水混凝土抗压性能影响。综合上述成果，揭示透水混凝土裂缝演变规律和破坏机理，研究成果将有望为高强透水混凝土的设计、开发和应用提供理论参考和技术支持。