跨原子-连续介质水泥基材料应变率效应形成机制研究

项目名称： 跨原子-连续介质水泥基材料应变率效应形成机制研究

项目编号： No.51479048

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 水利工程

项目作者： 周继凯

作者单位： 河海大学

项目金额： 82万元

中文摘要： 水泥基材料力学性能应变率效应属性的物理机制，无法从宏-细-微观唯像研究中获得，需要从纳米尺度（原子态）开展研究。本项目拟基于量子力学的分子动力学模拟条件下从头算，构建适用于描述材料力学性能的无定形C-S-H 凝胶结构模型；阐明原子态热活化、声子阻尼对应变率效应的控制机制；厘清水分子（毛细吸力、Stefan 效应）、温度、孔隙率、界面和尺寸效应对应变率效应的影响机制；探明惯性效应对应变率效应的作用规律；开发纳米尺度材料动态力学性能测试技术，结合宏观试验开展材料跨尺度动态性能测试，并与数值模拟相验证；开发水泥基材料动态力学性能多尺度（宏观、细观、微观、亚微观、纳观）计算方法；基于上述研究，揭示水泥基材料率效应形成的物理机制，建立水泥基材料动态力学性能跨原子-连续介质多尺度计算模型。本课题是一项跨学科基础性研究，为正确评价水泥基材料动态力学性能以及防止重大工程动力灾变探索一种崭新的研究手段。

中文关键词： 水泥基材料；应变率效应；多尺度；分子动力学模拟；机制

英文摘要： The physical mechanisms for rate effect of the mechanical properties of cement-based materials can not obtained from phenomenological research at macro, meso and micro scale. The relevant research should been carried out on nano-scale (atom state). Based on the quantum mechanics for ab initio, the non-fixed C-S-H gel model is established for describing the mechanical properties of cement-based materials by the molecular dynamics simulations. The controlling mechanisms of thermal activation and phonon damping on atom state for strain rate effects are illustrated. The influencing characteristics of water molecule (Capillary suction and Stefan effect), temperature, porosity, interfacial zone and size effect on strain rate effect are clarified, and the acting rules of inertial effect are investigated in this project. The measuring techniques for dynamic mechanical properties of cement-based materials at nano-scale are developed, and multi-scale dynamic mechanical tests combined with macro test are carried out. The test results are verified with results from numerical simulations. The calculating methods for the dynamic mechanical properties of cement-based materials from multi-scales (macro, meso, micro, submicro, and nano) will be proposed in this project. Based on the above researches, the physical mechanisms for the strain rate effects of cement-based materials is revealed, and multi-scale predicted models for dynamic mechanical properties from atom to continuous medium are presented. This project is an interdisciplinary and fundamental investigation, and can provide a new research method for assessing the dynamic mechanical properties of cement-based materials and damage evolution of civil infrastructure under strong earthquake and wind.

英文关键词： Cement-based materials;Strain rate effect;Multiscale;Molecular dynamics simulation;Mechanism