地下结构混凝土裂缝矿物自溶自修复机制及其多尺度时效性

The service performance of the underground structure is degraded by the concrete crack seriously. The mineral autolysis self-healing method is a promising crack healing approach for the concrete material. It can realize the crack self-healing for the concrete in the groundwater environment. With the concrete material of the underground structures as the objective, the project focus on the following studies by considering the service conditions (with the coupled effects of the load and the environment): The optimum design method is proposed for the mineral autolysis self-healing system based on the thermodynamics, the mathematical programming and the stochastic micromechanics, etc. The microstructure evolutions of the underground concrete during the mineral autolysis self-healing process are characterized using the electron microscope, energy dispersive spectrum (EDS) and computed tomography (CT) technologies, etc. The coupled effects of the load and environment are analyzed on the self-healing mechanism for the underground concrete. The multiscale evaluation framework is set up for the underground structures repaired by the mineral autolysis self-healing method. The constituents, the morphology and the properties of the mineral deposition products and the healing interface are analyzed by X-Ray Diffraction (XRD), the electron microscope and nanoindentation technologies, etc. The coupled effects of the load and the environment are studied on the healing effectiveness of the underground structures. The formation and evolution of the self-healing interface are analyzed based on the molecular dynamics simulation. The multiscale model for the performance evolution of the healed concrete is proposed considering the effects of the healing interface, mineral deposition products and the cracks, etc. The research achievements will disclose the crack self-healing mechanism and healing effectiveness evolution for the underground concrete repaired using the mineral autolysis self-healing method with the coupled effects of the load and the environment. The achievements will improve the long-term service performance of the underground structures.

混凝土裂缝严重影响地下结构健康服役性能。作为颇具前景的裂缝自修复新手段，矿物自溶自修复法可实现地下水环境下混凝土裂缝自修复。结合服役条件，本项目以荷载/环境耦合作用下的地下结构混凝土为对象: 基于热力学、数学规划和随机细观力学等建立矿物自溶自修复体系优化设计方法；采用电镜、EDS和CT技术等表征裂缝矿物自溶自修复过程地下结构混凝土微结构演化特征，揭示荷载/环境耦合作用对矿物自溶自修复机制影响规律；建立地下结构裂缝矿物自溶自修复效果多尺度评价方法，运用XRD、电镜和纳米压痕技术等分析矿物沉积产物和修复界面成分、形貌和性能；阐明荷载/环境耦合作用对裂缝自修复效果劣化机制；基于分子动力学模拟再现自修复界面形成和演化过程；建立含修复界面、沉积产物和裂缝等的地下结构混凝土性能演化多尺度模型。研究成果探清荷载/环境耦合作用下地下结构混凝土裂缝矿物自溶自修复机制和时效演变规律，提升地下结构长期服役性能。

混凝土裂缝对地下结构的健康服役性能有严重影响。矿物自溶自修复法可实现地下水环境中混凝土裂缝的自修复，针对矿物自溶自修复法实验研究和理论模型上的不足，本项目展开以下研究：基于热力学、数学规划和随机细观力学等，建立了自修复水泥基材料性能设计的最紧密堆积模型和随机细观力学模型等，形成了地下结构混凝土裂缝矿物自溶自修复体系优化设计方法；结合地下水环境下裂缝处的物质交换，构造出以PVP为保护膜、以水泥熟料为修复材料的矿物自溶自修复体系，实现了PVP保护膜在水泥熟料表面的装载；在已设计和制备的自修复体系基础上，通过裂缝预制并联合多种先进测试手段，揭示了地下结构混凝土裂缝矿物自溶自修复机制，探究了不同PVP掺量对自溶膜溶蚀功能的影响，发现PVP自溶膜的包覆能大幅提升自溶时间；评价了矿物自溶自修复愈合裂缝的效果，发现随着自溶微球掺量的增加，裂缝宽度愈合率增加，强度恢复率提高；同时，针对地下结构混凝土裂缝矿物自溶自修复进行了多尺度模拟，以矿物自溶自修复化学过程为基础提出了各因素修正中心粒子模型，为矿物自溶自修复进程提供理论基础，以细观力学方法为基础建立了矿物自溶自修复混凝土模量预测理论模型，探究了修复效率和自修复环境的影响规律，以自修复矿化的水化进程为主要修复机制，建立了基于连续损伤修复力学框架下的矿物水化自修复理论模型，分析了水胶比和修复时间等损伤自修复的影响。研究成果发表论文18篇以上；参加学术会议3次以上；培养研究生4名；形成了地下结构混凝土裂缝矿物自溶自修复体系的设计方法，探明其自修复机制及其影响因素，建立了自溶自修复体系的性能预测多尺度模型，为矿物自溶自修复提供理论基础，促进地下结构长期服役性能。