【作者】 杨洋；

【导师】 张东昱；

【作者基本信息】 哈尔滨工业大学 ， 建筑与土木工程（专业学位）， 2019， 硕士

【摘要】 钢筋混凝土结构已广泛应用于工程建设的各个领域,但在长期使用过程中,混凝土结构不可避免会产生裂缝,裂缝的不断扩展会严重影响结构的安全使用。现今已发展出很多混凝土裂缝监测方法,但其多基于点式传感器,存在对结构难以全面覆盖、监测效果不理想的缺点。同时,由于结构裂缝发生的随机性,导致传统的点式传感器无法有效捕捉裂缝信息,从而造成结构存在安全隐患,所以亟需研发一种能够实现全面感知混凝土结构裂缝信息的技术。本文提出一种基于分布式光纤布里渊增益谱的混凝土裂缝识别方法,运用高性能差分脉冲对-布里渊光时域分析(DPP-BOTDA)技术,对发生、扩展各阶段的混凝土裂缝监测方法进行了系统研究,并通过钢筋混凝土梁静载试验进行了验证,具体内容如下:(1)开展了分布式光纤混凝土梁裂缝监测的有限元数值模拟研究。首先通过有限元分析软件建立钢筋混凝土简支梁模型,采用四点弯的加载方式,研究梁中部纯弯段预设裂缝位置处应变场随荷载变化信息,分析粘结剂材料厚度、弹性模量等对分布式光纤应变传递效率的影响。(2)通过数值模拟分析,研究了基于DPP-BOTDA原理的泵浦光、连续光与光纤应变场的三波耦合作用。利用DPP-BOTDA工作原理,编制MATLAB程序,实现泵浦脉冲光、连续光与有限元模拟分析得出的裂缝位置处光纤应变场的三波耦合,分析得到了不同分辨率、不同荷载裂缝周围应变场下的布里渊增益谱变化特征。(3)建立了基于布里渊增益谱的混凝土裂缝识别方法。结合有限元模拟与数值模拟的分析结果,得出基于布里渊增益谱特征参数变化特性的混凝土裂缝识别方法,从而实现对裂缝发生、扩展各阶段的及时预警。(4)开展了分布式光纤混凝土梁裂缝监测试验。加工制作钢筋混凝土梁,通过在梁底布设分布式光纤,采用DPP-BOTDA技术对混凝土梁加载过程中裂缝开裂扩展进行监测,提取采集得到的布里渊增益谱数据,对已建立的识别方法进行验证。更多还原

【Abstract】 Reinforced concrete structures have been widely used in various fields of engineering construction,but in the long-term use process,concrete structures will inevitably produce cracks,and the continuous expansion of cracks will seriously affect the safe use of the structure.Many concrete crack monitoring methods have been developed today,but most of them are based on point sensors,which have the disadvantages that it is difficult to comprehensively cover the structure and the monitoring effect is not ideal.At the same time,due to the randomness of the occurrence of structural cracks,traditional point sensors cannot effectively capture crack information,resulting in hidden safety hazards in the structure.Therefore,it is urgent to develop a technology that can comprehensively sense the crack information of concrete structures.This paper presents a method for identifying concrete cracks based on the distributed fiber Brillouin gain spectrum,using high-performance differential pulse pair-Brillouin optical time domain analysis(DPP-BOTDA)technology to monitor the occurrence and expansion of concrete cracks at various stages.The method was systematically studied and verified by the static load test of reinforced concrete beams.The details are as follows:1.A finite element numerical simulation study of crack monitoring of distributed fiber-optic concrete beams was carried out.First,a finite element analysis software was used to establish a simple reinforced concrete beam model.The loading method of four-point bending was used to study the information on the change of the strain field at the preset crack position of the pure bend in the middle of the beam with the load.Influence of elastic modulus and other factors on strain transfer efficiency.2.Through numerical simulation analysis,the three-wave coupling effect of pump light,continuous light and fiber strain field based on DPP-BOTDA principle was studied.Based on the working principle of DPP-BOTDA,a MATLAB program was compiled to realize the three-wave coupling of the strain field of the fiber at the crack position obtained from the finite element simulation analysis of the pump pulse light,continuous light,and analysis.The strain field around the crack with different resolutions and different loads was obtained Brillouin Gain Spectrum Variation Characteristics.3.A concrete crack identification method based on Brillouin gain spectrum was established.Combining the analysis results of finite element simulation and numerical simulation,a concrete crack identification method based on the characteristics of Brillouin gain spectrum characteristic parameters is obtained,so as to realize timely early warning of crack occurrence and expansion at various stages.4.A crack monitoring test for distributed fiber-optic concrete beams was carried out.Reinforced concrete beams are processed and manufactured.By laying distributed optical fibers on the bottom of the beams,DPP-BOTDA technology is used to monitor crack growth during loading of the concrete beams.The Brillouin gain spectrum data collected is extracted and the established identification method is performed verification.更多还原