具有自学习功能的多参数原位表层混凝土传输性能测试平台“一体化”集成研究

Accurate evaluation of gas/water transport process within the near surface concrete is unavoidable in order to examine the durability of concrete structures. To achieve this, intrinsic material characteristics, including air permeability coefficient, sorptivity, water permeability coefficient, are needed. However, most conventional test techniques are unable to provide these parameters and hence, their results cannot be used in the service life prediction model directly. iMTS focuses on the development and application of a multi-parameter test system that could be used to solve this problem. Two new functional blocks, initial condition measurement block (to determine temperature, relative humidity and saturation degree) and field vacuum saturation block, will be integrated into the system to overcome key technical barriers for most in situ permeability assessments, the influence of the initial conditions of the concrete. Use of the self-learning algorithm will allow the assessment and elimination of environmental impacts on test responses. The whole project is built on a hierarchy of assessing moisture and air transports within the near surface concrete, starting from establishing a temporal-variant kinetic transport model and high throughput instrumentation, ending at proposing an integrated approach to achieve real-time and accurate assessment of moisture/air transport process. By its nature, iMTS is multidisciplinary and works across material engineering, electronic engineering, mechanic engineering, numerical modelling and instrumentation. As such, it addresses a number of work programmes which will improve our theoretical understanding of deterioration kinetics of concrete structures in aggressive environments, capabilities of analysing durability problems, establishing repair and maintenance methodology, and reduction of overall cost of structures.

正确认识液气在表层混凝土的传输过程、准确测定液气在表层混凝土传输速率是准确评估混凝土结构耐久性的基础。针对现有原位测试方法测试参数单一、测试结果无法直接应用在液气传输模型的瓶颈，本项目提出基于介质稳态传输的原位测试方法集成研究（iMTS），直接测评实体表层混凝土的透气系数、吸水系数、透水系数，通过建立混凝土初始条件（温度、湿度与含水量）与原位测试结果间关系，提出了消除混凝土初始条件对原位测试准确性影响的措施，采用补偿测试条件波动对原位测试系统影响的自学习算法，集成了一套新型的多参数原位混凝土传输性能测试方法，在此基础上，利用原位混凝土实测数据修正液气传输模型，提出了实时、准确表征液气在表层混凝土分布规律的“一体化”评价方法。本项目利用材料学、渗流力学、机电工程、软件工程、高精仪器、数值模拟、统计学等多学科交叉综合研究，为全面提升我国混凝土结构耐久性检测技术提供科学的理论依据与技术支持。

为突破现有混凝土结构耐久性评估所面临缺乏准确实体结构数据的技术瓶颈，有效发挥原位无损测试方法优势，本项目建立了表层混凝土原位渗透性测试方法原理、确立了表层混凝土渗透系数的求解方法、完成了原位表层混凝土渗透性测试方法的设计与加工、开展了原位渗透性测试方法精度研究、完成了原位渗透性测试方法可靠性研究、确定混凝土真空保水对原位渗透性测试结果影响；再次基础上，利用原位测试技术研究了极端服役条件下表层混凝土性能劣化规律、利用多参数测试系统评价、预测表层混凝土性能变化，并结合实际工程测试表层混凝土传输性能。本研究结合时变边界条件下液气传输模型，实时、准确分析液气在表层混凝土运动的过程，建立了原位测试系统与传输模型“一体化”测评方案，解决了现有原位方法测试参数单一、可重复性差、测试过程不稳定等问题。

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