海底隧道锈蚀型钢钢架与喷射混凝土粘结滑移退化本构关系研究

In the process of drilling and blasting construction in the submarine weak surrounding rock, it is the combined effects of profiled steelwork and sprayed concrete in the preliminary support of composite lining that endure the major surrounding rock pressure. Field measurements find that due to the chloride ion erosion the degradation of combined effects of profiled steelwork and sprayed concrete and the deterioration of bond-slip mechanical properties lead to the supporting capacity reduction of the primary support. As a result, the surrounding rock pressure is transferred to the secondary lining which has a great negative effect on the safety of supporting structure system. However, research on this effect both at home and abroad has not yet been conducted so far. Based on a large number of laboratory tests on the relations of corrosion rate and electrifying time, relations of corrosion rate and corrosion-induced expansion force and relations of corrosion rate, cohesive force and slip displacement, this project aims to reveal the minutiae features of pressure transmission of the combined effects of Profiled Steelwork and sprayed concrete by conducting elaborate three-dimensional simulations. Based on the availability of constitutive relations of bond–slip of non-corroded profiled Steelwork and sprayed concrete, an degenerated function containing unknown quantities is introduced to induce a theoretical formula of the constitutive relations of the bond-slip deterioration which contains this function. By comparing and contrasting this formula with the data of lab tests, the degenerated function is calculated with the mathematical analysis method to establish the constitutive relations under research. This research achievement is not only of practical value, but also enriches and develops the theories of bond-slip constitutive relationship models between corroded profiled steelwork and sprayed concrete.

钻爆法施工的海底隧道软弱围岩段，复合式衬砌中初期支护内型钢钢架与喷射混凝土联合作用，承受主要围岩压力。现场实测表明：型钢钢架受氯离子侵蚀，其与喷射混凝土联合作用被破坏，粘结滑移力学性能退化，初期支护承载能力减弱，围岩压力转移至二次衬砌，长期影响支护结构体系安全，但目前还未见有这方面的研究报道。本项目在进行型钢钢架喷射混凝土的锈蚀率-通电时间、锈蚀率-锈胀力、锈蚀率-粘结力-滑移位移等关系的大量室内试验基础上，对两者联合作用进行了三维精细化模拟，掌握其传力细节特征。在获得未锈蚀型钢钢架喷射混凝土粘结滑移本构关系基础上，通过引入含未知量的退化函数，推演出含该函数的粘结滑移退化关系理论式，将该理论式与大量室内试验结果进行对比，通过数学分析方法，求出退化函数，由此建立锈蚀型钢钢架喷射混凝土粘结滑移退化本构关系。本项研究成果不但具有实用价值，而且也丰富和发展了锈蚀型钢喷射混凝土粘结滑移退化理论。

海底隧道所处环境中氯离子、硫酸根离子等含量丰富，加之高水压对离子扩散的促进作用，支护结构体系中型钢钢架容易受离子侵蚀作用脱钝而锈蚀，其与喷射混凝土联合作用被破坏，粘结滑移力学性能退化，导致初期支护承载能力减弱，围岩压力转移至二次衬砌，长期影响支护结构体系安全。为此，本项目采用文献调研，开展电加速锈蚀及型钢钢架混凝土推出试验，建立型钢钢架混凝土推出非线性数值模型，基于随机损伤理论分析等，围绕海底隧道型钢钢架锈蚀率与通电时间关系、锈蚀率与锈胀力关系、型钢钢架与混凝土界面力学传力特征与本构模型开展研究。首先，开展了未锈蚀型钢钢架与混凝土间的推出试验，得到了未锈蚀型钢钢架-混凝土界面粘结滑移本构关系，基于此粘结滑移本构采用数值模拟手段得到了二者细节传力特征；其次，开展了型钢钢架混凝土电加速锈蚀试验，得到了型钢钢架锈蚀率分别与通电时间、锈胀力的关系式；最后，将不同保护层厚度和锈蚀率的型钢钢架混凝土构件进行推出试验，得到了粘结应力τ-滑移S曲线，揭示了型钢钢架锈蚀致混凝土界面粘结退化机制及力学特性，构建了基于随机损伤理论的锈蚀型钢钢架与混凝土界面粘结滑移退化本构模型，同时基于粘结滑移退化本构关系采用数值模拟手段得到了锈蚀型钢钢架与混凝土间的细节传力特征。本项研究揭示了型钢钢架与混凝土界面的力学传递机制，提出了型钢钢架与喷射混凝土的粘结滑移退化本构关系，为解决型钢钢架锈蚀致初期支护承载力衰减提供了基础，不但具有指导海底隧道支护体系设计、施工、维护、维修的实际应用价值，而且丰富和发展了锈蚀型钢喷射混凝土粘结滑移退化理论。