高应力与腐蚀介质协同作用下岩土预应力锚索耐久性及其损伤演化机理研究

Stress corrosion has become the principal factor that can affect the long-term durability of geotechnical prestressed anchorage cable. Through the indoor accelerated corrosion test, we can explore how the synergistic effect of high stress and corrosive medium influences the long-term durability of geotechnical prestressed anchorage cable, then respectively establish the quantitative relationship of cable unit length corrosion and the factors such as stress level, corrosion medium pH value and time, revealing the macro regularity of prestressed cable-body corrosion durability. Based on this, using the genetic algorithm, the prediction model of service life including the above-mentioned factors for prestressed anchorage cable will be established. In addtion, combined with the field test results, the life prediction model will be revised to be applied to practical projects. At the same time, the advanced three-dimensional figure microscopic observation system with large depth of field and SEM (scanning electron microscope) will be used to observe the cable-body corrosion damage morphology and micro structure under different corrosion time. From this, we can reveal the macro-micro mechanism of prestressed cable damage evolution under the synergistic effect of high stress and corrosive medium and establish the correspondence and correlation of macro-meso physical quantities. The research not only can provide a reliable evaluation method for major projects in geotechnical prestressed anchor cable corrosion durability prediction, but also can provide a new ideas for its corrosion mechanism study.

应力腐蚀已成为影响岩土预应力锚索长期耐久性的主要因素。本项目研究通过室内加速腐蚀试验，探寻高应力与腐蚀介质协同作用对岩土预应力锚索体长期耐久性的影响，分别建立应力水平、腐蚀介质pH值、时间等因素与索体单位长度腐蚀量的定量关系，揭示预应力索体腐蚀耐久性的宏观规律。在此基础上，利用遗传算法建立考虑以上影响因素的预应力索体服役寿命预测模型，并结合现场试验成果，对室内试验所得到的寿命预测模型进行修正，以使其能够应用于实际工程中预应力索体服役寿命的预测。同时，利用先进的超景深三维数字显微观测系统及SEM（扫描电子显微镜）等对不同腐蚀时间下索体试件的锈蚀损伤形貌及微观组织结构进行观测，揭示高应力与腐蚀介质协同作用下预应力索体损伤演化的宏细观机理，建立宏观-细观物理量之间的对应与关联。研究成果不仅能为重大工程中岩土预应力锚索腐蚀耐久性的预测提供可靠的评估方法，还能为其腐蚀机理的研究提供新思路。

岩土预应力锚固结构以其诸多优点广泛应用于高边坡、深基坑、大坝等岩土加固工程中，但应力腐蚀已成为影响其长期耐久性的关键因素。课题通过调研实际工程中岩土预应力锚固边坡水、岩土体腐蚀介质成分及预应力锚固结构腐蚀现状，确定了影响岩土预应力锚固结构腐蚀耐久性的因素。通过研制室内加速腐蚀试验装置，进行了2种杆体材料（索体及杆体）、6组酸碱pH值、5组应力水平及6个腐蚀时间下共计360根杆件的正交试验，分别建立了应力水平、腐蚀介质pH值、时间及杆体材料等因素与单位长度腐蚀量、断面损失率的定量关系。同时基于索（杆）体断裂破坏准则建立了包含以上各腐蚀影响因素的岩土预应力锚固结构腐蚀服役寿命预测模型，并对该基于室内加速腐蚀试验得出的预测模型进行了实际工况下杆件直径及腐蚀环境差异两方面的修正，最后将预测模型应用于某实际工程中，验证了该预测模型的可靠性。最后基于超景深三维数字显微系统及SEM（扫描电镜）等对不同腐蚀时间下的索体锈蚀损伤形貌进行观测，建立了平均腐蚀深度、腐蚀坑长轴长度、腐蚀坑面积等指标与时间的关系，并从索体断口的细观组构方面分析了高应力与腐蚀介质协同作用下的杆体损伤演化机制。项目研究成果不仅能为重大工程中岩土预应力锚固结构的使用寿命预测提供较为准确、可靠的评估方法，还能为其腐蚀机理的研究提供新思路。

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