钢纤维混凝土管片的力学性能及纤维分布规律研究

This project attempts to study the mechanical properties of steel fibre reinforced concrete segment (SFRCS) and the fibre distribution within it by means of combining the physical test and numerical simulation methods. Firstly, the reinforcing and toughening properties of steel fibres would be studied by testing specimens with different fibre dosages; and the mechanical properties of SFRCS will be tested through the full-scale bending test. Secondly, the fibre distribution would be studied in 2 steps: first, performing Inductive Test and Barcelona Test on cores which are drilled from the tested segment; second, establishing a fibre distribution model within the segment by using mathematical statistics analysis results. Based on the model, this study also attempts to establish a PFC/FLAC3D coupled numerical model of SFRCS and to make simulation. By comparative analyzing the numerical simulation and experimental results, the parameters of the model would be debugged until the error of the macro-properties (such as load and mid-span deflection) and experimental results are controlled within 3%. Finally, using this model to simulate the bending and impacting resistance of SFRCS with different volume fraction under varied loads, and then determine the quantitative relationship of design parameters of segment according to the simulation results, thus to provide evidence for the designing and application of SFRCS...Through this project, the economic losses caused by the conservative design of SFRCS, which was adopted due to the uncertainty of fiber orientation factor, might be reduced. Therefore, this study will be of great significance in the promotion of the utilization of SFRCS in the construction of urban underground railway.

本项目拟采用物理试验与数值模拟结合的方法，对钢纤维混凝土管片（SFRCS）的力学性能及纤维分布规律展开研究。首先，通过测试不同钢纤维含量的混凝土试件，研究纤维的增强、增韧性能，并通过抗弯试验研究SFRCS的力学性能；其次，结合管片取芯试件电感试验和巴塞罗那试验结果，利用数理统计分析方法，合理建立纤维在管片内的分布模型；再依据该模型建立SFRCS的PFC/FLAC3D耦合模型并模拟，直至其宏观性能（荷载，跨中挠度等）与试验结果相比误差在3%以内；最后，用该模型模拟不同纤维体积率时SFRCS在外荷载作用下的抗弯抗冲击等性能，结合模拟结果确定管片设计参数之间的定量关系，为SFRCS的设计应用提供依据。..通过该项目的研究，可以减少在SFRCS设计中因不能确定“纤维分布因子”的影响而采用保守设计方案带来的经济损失，对推广SFRCS在我国城市地下铁道建设中的应用将会有重要推进作用。

截止2019年底，我国在建轨道交通城市有44个，通车里程已超过5500km，预计至“十三五”末，全国城市轨道交通运营线路长度将达6500km以上，这其中，超过65%的区间隧道采用盾构法施工。盾构隧道的衬砌一般采用具有一定强度且加工制作比较容易的钢筋混凝土管片。但因混凝土为脆性材料，其抗折、抗拉和抗冲击性能较差，对早期开裂也十分敏感，故在实际应用中存在诸多问题。本项目通过物理试验与数值模拟结合的方法，对钢纤维混凝土管片（SFRCS）的力学性能及纤维分布规律展开研究。首先，测试了不同钢纤维含量的混凝土试件，对钢纤维提高混凝土强度和韧性方面有了定性认知；然后通过管片足尺抗弯试验研究SFRCS的力学性能，并在试验后对管片进行坐标标定取芯，并对取芯试块进行了电感试验和巴塞罗那试验。结合试验结果，利用数理统计分析方法，合理建立纤维在管片内的分布规律模型；基于钢纤维在立方体试块内的试验结论，利用ABAQUS有限元软件进行纤维定向投放并模拟，结果验证了钢纤维分布规律的准确性。..项目研究结果以数据为支撑，具有很强的理论指导意义，纤维分布系数的引入可直接用以指导SFRCS的结构设计，这将对钢纤维混凝土管片的推广应用起到促进作用。