【作者】 施毅；

【导师】 汪昕；

【作者基本信息】 东南大学 ， 土木工程， 2024， 硕士

【摘要】 在国家大力发展交通基础设施的背景下,隧道作为关键的交通组成部分,其安全运营尤为重要。隧道衬砌的健康状况直接关系到隧道的安全性能,因此针对隧道衬砌病害的加固技术研究具有重要意义。现有的加固技术如注浆加固法、套拱加固法、粘贴钢板加固法及FRP片材粘贴加固法等。但注浆加固法加固效果受地质条件显著影响,套拱加固新增截面存在应力滞后,粘粘钢板加固法需要大量额外锚固措施,FRP片材粘贴加固法易出现界面破坏,鉴于现有技术不足,有必要探索更为有效的隧道加固方法。而纤维增强聚合物(Fiber Reinforced Polymer,FRP)网格作为一种新兴的加固材料,其力学性能优异,轻质高强、节点强度高、耐疲劳以及耐久性好,其中玄武岩纤维FRP(BFRP)更是有绿色环保、可回收等独特优势,在土木工程领域逐渐受到关注。地聚物砂浆具有早强快硬、和骨料的界面结合能力好、耐高温隔热效果好、抗冻融循环能力强、碳排放量低等优点,但地聚物砂浆在早期阶段易产生干燥收缩,收缩应力会引起基体开裂,影响加固效果,可以通过在地聚物砂浆中掺入纤维抑制其收缩以满足隧道加固要求。因此,本文通过试验研究以及有限元模拟系统分析BFRP网格-玄武岩纤维(Basalt Fiber,BF)增强地聚物砂浆加固隧道衬砌管片的受弯性能,并为实际工程应用提供设计和应用参考。主要研究内容及成果如下:(1)BFRP网格加固隧道衬砌管片受弯性能试验研究。通过设置网格厚度、粘结材料、养护龄期以及原配筋率对9根缩尺隧道管片进行四点受弯试验,对比分析各管片在受力过程中的裂缝分布与扩展、开裂弯矩、极限弯矩,以及跨中弯矩-位移曲线和BFRP网格应变-位移曲线等试验现象,以评估这些参数对BFRP网格加固管片受弯性能的影响。试验结果显示,增加BFRP网格厚度、使用纤维增强地聚物砂浆作为粘结材料、保证充足养护龄期以及提高原配筋率,可有效提高加固管片包括开裂弯矩、极限弯矩、抗弯刚度等在内的受弯性能。BFRP网格加固管片破坏模式主要表现为适筋受弯破坏,而在原配筋率过高情形下,可能导致加固管片转向脆性超筋受弯破坏。(2)BFRP网格加固隧道衬砌管片受弯性能有限元参数分析。构建BFRP网格-纤维增强地聚物砂浆加固管片有限元分析模型,通过与试验结果的对比分析,验证有限元模型的准确性。在确保其可靠性和有效性的前提下,进一步探讨影响BFRP网格-纤维增强地聚物砂浆加固管片受弯性能的关键参数。这些参数包括混凝土强度、管片的初始配筋率以及BFRP网格的厚度。通过对这些变量进行系统参数分析,深入理解BFRP网格加固在提升管片受弯性能方面机理。有限元模型预测结果表明,随着混凝土强度提高、管片原配筋率增大以及BFRP网格厚度增加,管片的受弯性能显著提升。(3)BFRP网格加固隧道衬砌管片承载力计算理论方法研究。根据《混凝土结构设计规范》、《纤维增强复合材料工程应用技术规范》以及《公路隧道加固技术规范》等相关规定,本研究对BFRP网格-纤维增强地聚物砂浆加固的隧道衬砌管片进行受弯承载力理论计算公式进行推导。在理论分析基础上,结合有限元计算结果,对承载力公式进行修正,并通过试验数据验证其准确性。为实际工程应用提供设计参考。更多还原

【Abstract】 Under the backdrop of the nation’s vigorous development of transportation infrastructure,tunnels,as a key component of transportation,play a particularly important role in safe operation.The health condition of tunnel lining directly relates to the safety performance of the tunnel,thus research on reinforcement techniques for tunnel lining diseases is of great significance.Existing reinforcement techniques include grouting reinforcement,arch-shell reinforcement,steel plate bonding,and FRP(Fiber Reinforced Polymer)sheet bonding methods.However,the effectiveness of grouting reinforcement is significantly influenced by geological conditions;arch-shell reinforcement introduces stress lag in the added cross-section;steel plate bonding requires a large number of additional anchoring measures;and FRP sheet bonding is prone to interface failure.Given the shortcomings of current technologies,it is necessary to explore more effective tunnel reinforcement methods.Fiber Reinforced Polymer(FRP)grids,as an emerging reinforcement material,exhibit excellent mechanical properties:they are lightweight yet strong,have high nodal strength,fatigue resistance,and durability.Among them,Basalt Fiber Reinforced Polymer(BFRP)has unique advantages such as being environmentally friendly and recyclable,gradually gaining attention in the field of civil engineering.Geopolymer mortar has the advantages of early strength development,good interfacial bonding with aggregates,excellent high-temperature insulation,strong resistance to freeze-thaw cycles,and low carbon emissions.However,geopolymer mortar is prone to dry shrinkage at early stages,which can cause cracking in the matrix and affect the reinforcement effect.This shrinkage can be mitigated by incorporating fibers into the geopolymer mortar to meet the requirements for tunnel reinforcement.Therefore,this paper systematically analyzes the flexural performance of BFRP grid and Basalt Fiber(BF)enhanced geopolymer mortar in reinforcing tunnel lining segments through experimental research and finite element simulation,filling the research gap in the application of BFRP grids in tunnel lining reinforcement and providing references for design and application in practical engineering.The main research contents and findings are as follows:(1)Experimental research on the flexural performance of BFRP grid-reinforced tunnel lining segments.By setting up parameters such as grid thickness,bonding materials,curing age,and original reinforcement ratio,four-point bending tests were conducted on nine scaled tunnel segments.Comparative analysis was performed on the crack distribution and propagation,cracking moment,ultimate moment,mid-span moment-displacement curves,and BFRP grid strain-displacement curves during the loading process to evaluate the influence of these parameters on the flexural performance of BFRP grid-reinforced segments.The test results show that increasing the thickness of the BFRP grid,using fiber-enhanced geopolymer mortar as the bonding material,ensuring sufficient curing age,and increasing the original reinforcement ratio can effectively improve the flexural performance of the reinforced segments,including the cracking moment,ultimate moment,and flexural rigidity.The failure mode of BFRP grid-reinforced segments mainly manifests as appropriate flexural failure,but excessive original reinforcement ratio may lead to brittle over-reinforced flexural failure.(2)Finite element parametric analysis of the flexural performance of BFRP grid-reinforced tunnel lining segments.A finite element analysis model of BFRP grid and fiber-enhanced geopolymer mortar-reinforced segments was constructed and verified for accuracy by comparing with experimental results.Upon ensuring its reliability and effectiveness,further investigation was conducted on the key parameters affecting the flexural performance of BFRP grid and fiber-enhanced geopolymer mortar-reinforced segments.These parameters include concrete strength,initial reinforcement ratio of the segment,and the thickness of the BFRP grid.Through systematic parametric analysis of these variables,an in-depth understanding of the mechanism by which BFRP grid reinforcement enhances the flexural performance of segments was gained.The finite element model predictions indicate that with increased concrete strength,higher original reinforcement ratio of the segment,and greater thickness of the BFRP grid,the flexural performance of the segment significantly improves.(3)Research on theoretical calculation methods for the bending capacity of tunnel lining segments reinforced with BFRP grids.Based on relevant specifications,this study derived theoretical calculation formulas for the bending capacity of tunnel lining segments reinforced with BFRP grids and fiber-enhanced geopolymer mortar.On the basis of theoretical analysis,combined with finite element calculation results,the capacity formula was revised and verified for accuracy with experimental data,providing a design reference for practical engineering applications.更多还原