受拉侧锈蚀钢纤维-钢筋混凝土管片承载力退化模型研究

近年来，国内外新建盾构隧道与管道工程中采用钢纤维-钢筋混凝土管片愈来愈多，在侵蚀环境下管片钢筋锈蚀的问题突出，提出适用于锈蚀后钢纤维-钢筋混凝土管片的残余承载力计算的方法十分重要。鉴于此，文章根据服役期盾构隧道管片所处环境及受力特征，结合钢筋混凝土结构正截面承载力计算理论，提出受拉侧锈蚀钢纤维 钢筋混凝土管片承载力退化模型，并给出相应的求解流程。同时，分析不同锈蚀率与不同钢纤维掺量下受拉侧锈蚀钢纤维-钢筋混凝土管片承载力曲线，并将该模型理论解与压弯荷载作用下钢纤维-钢筋混凝土管片的同步加速锈蚀室内试验结果进行比较，验证了该模型的适用性和可靠性。主要结论有：①随着钢纤维的掺量增加，混凝土的立方体抗压强度会先增大后减小；②偏心受压管片构件极限弯矩最大值随主筋锈蚀率的增大而不断减小，随钢纤维掺量的增大而不断增大，但增大幅度逐渐减小；极限轴力最大值受主筋锈蚀率的影响不大，但随钢纤维掺量先增大后减小。③主筋锈蚀率与钢纤维掺量对大偏心受压构件的影响均大于小偏心受压构件；界限偏心距随主筋锈蚀率的增大而减小，随钢纤维掺量的增大而增大。

Study on bearing capacity degradation model for corroded steel fiber reinforced concrete segments on tension side

In recent years, more and more steel fiber reinforced concrete(SFRC) segments are used in new shield tunnel and pipeline engineering. Meanwhile, in the corrosive environment, many segments face the problems of reinforcement corrosion. Under such circumstance, it is necessary to propose a calculation methods for residual bearing capacity of corroded SFRC segments. In this paper, a degradation model of corroded SFRC segments on tensile side is proposed according to the environment and stress characteristics of shield tunnel segments in service period. The calculation theory of bearing capacity of reinforced concrete structures is deduced and the corresponding solution steps are given. The bearing capacity curves of corroded tensile side SFRC segments with different corrosion level and different steel fiber content are analyzed. The analysis results by the proposed model are compared with the results of the synchronous accelerated corrosion of SFRC segments under compressive and bending loads to verify the applicability and reliability of the model. The main conclusions are as follows:① With the increase of steel fiber content, the cube compressive strength of concrete first increases and then decreases;② The maximum ultimate bending moment of eccentrically compressed segment decreases with the corrosion level of main reinforcement, but increases with the steel fiber content, but the increase amplitude decreases gradually; The maximum ultimate axial force is not affected by the corrosion level ofmain reinforcement, but increases first and then decreases with the steel fiber content. ③ The influence of corrosion ratio of main bars and steel fiber content on large eccentric compression members is greater than that on small eccentric compression members. The balanced eccentricity decreases with the corrosion level of main reinforcement and increases with the steel fiber content.