顺层岩坡预应力锚固结构服役寿命评价与灾变机理研究

Research of service life of prestressed anchorage structure in slope is in the initial stage in China, and the study on service life and disaster mechanism of prestressed anchorage structure is one of the most urgent topics in the development of geotechnical anchoring technology. on the background of research on service life and disaster mechanism of prestressed anchorage structure in rock bedded slope which is very common in the Three Gorges Reservoir Area, the disaster causes model and spatial distribution model will be established, based on field geological survey and analysis of stress corrosion and chemical corrosion. Simultaneously, the multi-factor anchoring physical model test considering corrosion, rheology and environmental change, stress corrosion acceleration test of single anchor and compressive creep test of model material will be carried out in labs, and then the prestress losses model of anchor system would be established, which can consider the coupling effect of slope creep and corrosion damage of anchorage structure. Based on the research results above, numerical simulation will be employed to find the main failure mode and catastrophic evolution process of supporting project. Finally the evaluation theory of service life of prestressed anchorage structure will be established. This study has both theoretical significance and innovation, and also shows practical significance and application value.

边坡预应力锚固结构的服役寿命研究在我国尚处于起步阶段，开展其服役寿命及灾变机理研究是岩土锚固技术发展中最为紧迫的研究方向之一。本课题拟以我国三峡库区较为常见的顺层岩坡预应力锚固结构工程为依托，开展服役寿命评价及灾变机理研究，在典型锚固边坡工程现场地质调查及化学腐蚀、应力腐蚀分析测试基础上，构建其灾变成因模型及空间分布模型；在室内开展拟环境多因素物理模型锚固腐蚀流变试验，典型工况下单锚应力腐蚀加速试验以及模型材料压缩蠕变等试验，考虑坡体蠕变及锚固体腐蚀损伤相互耦合的特点，建立锚固工作体系预应力变化模型。基于上述研究成果，开展数值模拟研究，研究依托工程的主要失效模式及灾变过程，建立边坡预应力锚固结构服役寿命评价理论及锚固体系健康状况辨识指标。本项研究既具有理论意义和创新性，同时也具有现实意义和应用价值。

为探索预应力锚固结构在岩土环境下腐蚀发展规律及其损伤对锚固边坡稳定性影响，综合运用室内模型试验、电化学测试分析及智能分析预测等手段，开展了典型边坡地质化学环境调研与测试、腐蚀环境下预应力锚杆损伤机制、预应力锚杆腐蚀损伤分析及寿命预测、腐蚀环境下锚固顺层边坡时效演化行为等方面的研究，取得了如下主要研究成果：. （1）对三峡库区典型锚固边坡的地质条件、岩锚现状等进行调查分析，并在室内对岩土体的矿物化学特性长期演化规律进行测试，确定了预应力锚固结构赋存的岩土环境，为预应力锚固结构耐久性研究及预应力锚固结构防腐设计奠定了基础。. （2）通过有、无预应力条件腐蚀环境下锚筋的电化学测试，揭示了锚筋腐蚀速率的变化规律及预应力对其影响；在锚筋浸泡腐蚀试验中开展局部应变测试，发现局部腐蚀是影响预应力锚固结构的控制性因素，为研究预应力锚筋局部腐蚀行为研究奠定了基础。. （3）通过预应力锚杆腐蚀损伤分析，研究了预应力锚固结构损伤机制；基于预应力锚杆腐蚀损伤与岩体的松弛耦合分析，建立了顺层岩坡的锚固工作体系预应力变化统一模型；结合筋材腐蚀强度损伤，以杆体材料变化的极限承载能力为判据，建立岩土预应力锚固结构服役寿命预测方法。. （4）开展了腐蚀环境下锚固顺层边坡时效演化行为模型试验，研究表明预应力锚固结构自由段的腐蚀未明显加速锚筋预应力损失，锚固结构腐蚀对边坡变形稳定的影响机制主要体现在腐蚀引起锚筋失效或锚固段腐蚀引起预应力大幅度降低，加深了对腐蚀环境下锚固边坡稳定性退化机理的认识。