考虑颗粒变形的岩土松散体宏/细观强度关联性及其跨尺度模型

The geo-granular materials are typical granular matter in soft matter theory. The mechanical properties of geo-granular materials are multi-scale problem, e.g. physical levels and structural scales. The Meso-scale studying is the bridge to combine the Macro and Micro scales information. In this project, Macro and Meso trans-scale correlation of geo-granular material based on the photoelasticity experiment and soft mater mechanics would be studied. Moreover, the traditional discrete element method would be modified to get rid of the affection of the overlap contract treatment among particles. The imaging process technical would be used to get the meso-scale parameters quantificationally during the granular shearing. The Macro and Meso trans-scale correlation would be proposed based on the soft mater mechanics and the experimental results. The point and face contact treatment would be applied into the discrete element method instead of the overlap treatment. The comparison and analysis between experimental and numerical simulation would be conducted to verify the correction of the numerical simulation results. Overall, this project achievements would reveal the mechanism of geo-granular material deformation to realize the cross fusion of granular mechanics and soil mechanics. It would provide a strong promotion to the experimental and simulated study on the geo-granular materials in Marco/Meso scale. Therefore, this project possesses enormous academic value and broad prospect in engineering applications induced geological hazards prevention.

岩土松散体属于典型的颗粒物质范畴，其力学行为涉及多物理层次和多结构尺度等多尺度问题。细观尺度研究则是联系微观和宏观的桥梁。本项目拟针对岩土松散体宏/细观跨尺度问题，以光弹测试技术为基础，开展不同围压、剪切速率的颗粒材料剪切试验，结合软物质力学理论进行岩土松散体剪切破坏的宏/细观跨尺度关联研究，建立岩土松散体剪切破坏新理论以及数值模拟新方法。采用数字图像处理技术，定量提取颗粒材料剪切过程中的细观参量演化信息；基于软物质力学理论综合对比，分析不同剪应变下颗粒材料的宏观力学表现与细观参量之间的跨尺度关联，建立岩土松散体剪切宏观破坏的细观数学模型；通过采用“点”、“面”接触方式对传统的数值模拟进行修正，并将数值模拟结果与试验结果进行对比分析。预期成果对于揭示岩土松散体的土性弱化机制，推动岩土松散体的宏/细观多尺度试验与数值模拟研究，以及相关地质灾害的防治等均具有重要的理论和工程实践意义。

由碎散物质组成的地质体失稳流滑大变形所致的地质灾害严重影响国民经济发展和人民生命财产安全，绝大多数造成此类地质灾害的对象属于颗粒物质。颗粒物质是由大量离散颗粒组成的复杂无序体系，其力学特性极为复杂。地质工程领域中，典型的地质灾害现象如滑坡、泥石流等都与颗粒物质力学密切有关。本项目以岩土松散体的剪切破坏为研究对象，结合颗粒物质力学，通过颗粒物质光弹试验，并结合高精度、高速采集频率的图像采集系统，针对颗粒材料剪切相变过程中宏/细观跨尺度关联开展了大量的研究工作，取得了系列创新性成果，主要体现在：自主研制了光弹颗粒材料双轴剪切试验装置，可实现对颗粒材料进行体积分数控制的双轴剪切；揭示了岩土颗粒材料剪切带演化过程中，细观力链网络分布、颗粒转动量与剪切带位置的关联特性；揭示了结构物在颗粒材料内部发生剪切移动时颗粒系统内部宏/细观跨尺度关联特性；开展了颗粒变形对颗粒系统剪切特性的影响研究，考虑颗粒与水作用膨胀后，颗粒由弹性体变为粘弹性颗粒，揭示了典型颗粒系统发生非连续剪切增稠的物理机制，并自主研制了具有非连续剪切增稠性质的颗粒材料。上述成果对进一步阐明岩土松散体剪切破坏机理，为我国高速城市化建设，尤其是山区城市化建设过程中避免由岩土松散体变形破坏所致地质灾害研究提供可靠且有力的科学参考，指导山区城市建设的工程实践和防灾减灾具有重要意义。