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A fiber optic sensor for detecting and monitoring cracks in concrete structures

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Science China(Technological Sciences) 2010年第11期53卷 3045-3050页

作者： bao tengfei WANG JiaLin YAO Yuan State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210024China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai UniversityNanjing 210024China

The formation and propagation of cracks reflect the aging and pathologic changes of concrete structures and may cause problems such as seepage and long-term durability. Crack detection and monitoring is therefore an effective way to evaluate structural health conditions. An important challenge in such a task is that the locations and orientations of cracks in concrete structures are difficult to predict due to material inhomogeneity and complexity. The number of the required conventional electric and electromagnetic sensors to cover all possible cracks may be too large to be practical for a monitoring scheme. In this paper, a fiber optic sensor with distributed crack sensing capability based on optical time domain reflectometry is proposed and its sensing principle is introduced. Experiments are conducted to obtain the optical power loss versus crack opening at different fiber inclination angles, and then a model is developed to quantify it. Finally, an experiment is performed to demonstrate the practical application of the sensor. The test results show that detecting and monitoring cracks with the sensor do not require a-priori knowledge of crack locations and orientations.

关键词： fiber optic sensor crack concrete

BIM-based framework of automatic tunnel segment assembly and deviation control

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Underground Space 2024年第3期16卷 59-78页

作者： Jian Gong tengfei bao Zheng Zhu Hong Yu Yangtao Li The National Key Laboratory of Water Disaster Prevention Hohai UniversityNanjing 210098China College of Water Conservancy and Hydropower Engineering Hohai UniversityNanjing 210098China College of Hydraulic and Environmental Engineering China Three Gorges UniversityYichang 443002China Zhejiang Design Institute of Water Conservancy and Hydro-Electric Power Hangzhou 310002China

The design of universal segments and deviation control of segment assembly are essential for robust and low-risk tunnel construction.A building information modeling(BIM)-based framework was proposed for parametric modeling,automatic assembly,and deviation control of universal ***,segment models of different levels of detail(LoDs)were built based on BIM visual programming language(VPL)for different project life ***,the geometric constraints,requirements,and procedures for parametric segment assembly were distilled to develop a program that combines a novel typesetting algorithm with a 3D path replanning *** is implemented by introducing a point indication matrix,characterizing segments by sides,and manipulating geometries in a ***,3D path replanning,with non-uniform rational B-splines(NURBS)and arcs as basic shapes,was used to resolve unacceptable deviation situations after ***,the proposed framework was validated on a water diversion line and was found to be more effective and accurate than the previous method.

关键词： Parametric generative design BIM Deviation control Typesetting 3D path replanning

Abnormality monitoring model of cracks in concrete dams

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Science China(Technological Sciences) 2011年第7期54卷 1914-1922页

作者： bao tengfei QIN Dong ZHOU XiWu WU GuiFen State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing 210098 China Jiangsu Province Water Resources Engineering Consulted Co. Ltd Nanjing 210029 China China Huadian Engineering Co. Ltd. Beijing 100035 China

The abnormality monitoring model (AMM) of cracks in concrete dams is established through integrating safety monitoring theories with abnormality diagnosis methods of cracks. In addition, emphasis is placed on the influence of crack depth on crack mouth opening displacement (CMOD). A linear hypothesis is proposed for the propagation process of cracks in concrete based on the fictitious crack model (FCM). Abnormality points are detected through testing methods of dynamical structure mutation and statistical model mutation. The solution of AMM is transformed into a global optimization problem, which is solved by the particle swarm optimization (PSO) method. Therefore, the AMM of cracks in concrete dams is established and solved completely. In the end of the paper, the proposed model is validated by a typical crack at the 105 m elevation of a concrete gravity arch dam.

关键词： concrete dam cracks abnormality monitoring model a linear hypothesis abnormality diagnosis particle swarm optimization method

Parameter sensitivity and inversion analysis of a concrete faced rock-fill dam based on HS-BPNN algorithm

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Science China(Technological Sciences) 2016年第9期59卷 1442-1451页

作者： SUN PengMing[[ bao tengfei[[ GU ChongShi[[ JIANG Ming WANG Tian[[ SHI ZhongWen[[ College of Water-conservancy and Hydropower Hohai University Nanjing 210098 China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China Hydrochina Huadong Engineering Corporation Hangzhou 310014 China

Considering the complex nonlinear relationship between the material parameters of a concrete faced rock-fill dam(CFRD) and its displacements, the harmony search(HS) algorithm is used to optimize the back propagation neural network(BPNN), and the HS-BPNN algorithm is formed and applied for the inversion analysis of the parameters of rock-fill materials. The sensitivity of the parameters in the Duncan and Chang's E-B model is analyzed using the orthogonal test design. The case study shows that the parameters φ0, K, Rf, and Kb are sensitive to the deformation of the rock-fill dam and the inversion analysis for these parameters is performed by the HS-BPNN algorithm. Compared with the traditional BPNN, the HS-BPNN algorithm exhibits the advantages of high convergence precision, fast convergence rate, and strong stability.

关键词： parameter sensitivity analysis harmony search algorithm back propagation neural network parameter inversion concrete faced rock-fill dam

Influence of fractality of fracture surfaces on stress and displacement fields at crack tips

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Science China(Technological Sciences) 2008年第S2期51卷 95-100页

作者： bao tengfei,WU ZhongRu,GU ChongShi & GU YanLing College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210098,China College of Water Conservancy and Hydropower Engineering Hohai University Nanjing China

In the classic theory of fracture mechanics,expressions for calculating the stresses and displacements in the vicinity of the crack tip are deduced on the basis of the assumption that a fracture surface is a smooth surface or that a crack is a smooth *** fact,the surface of a crack formed during the fracture is usually very *** the real asymptotic form of the stress and displacement fields at the crack tip is different from the classic *** the irregularity of a real fracture surface or a real crack profile,the crack is taken as a fractal one,and then the real asymptotic form at the crack tip is developed by applying Griffith's energy balance principle and fractal *** the developed asymptotic form,it is discovered that the fractality of the crack reduces the stress singularity at the crack tip.

关键词： fracture surface crack fractal stress and displacement fields

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大坝群自动监测报警系统

水力发电学报 2005年第5期24卷 119-122,118页

作者：李婷婷包腾飞河海大学水利水电工程学院南京210098

为及时掌握大坝运行性态,采用现代网络、通信技术,开发大坝群自动监控报警系统,实现对大坝群安全远程实时监控。利用大坝安全综合评价专家系统的评判结果,开发web程序进行远程安全自动报警。系统采用模块化设计,结构灵活,适用性强。

关键词：大坝群报警系统远程监控专家系统

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混凝土裂缝分布式光纤光栅监测能力研究

压电与声光 2011年第4期33卷 540-543页

作者：包腾飞钱飞河海大学水文水资源与水利工程科学国家重点实验室江苏南京210024 河海大学水资源高效利用与工程安全国家工程研究中心江苏南京210024

深入分析了光纤布喇格光栅(FBG)裂缝传感原理,研究了基于FBG传感的分布式裂缝监测技术。为验证FBG裂缝传感的可行性,进行了混凝土模型试验发现,FBG能准确监测到裂缝发生和扩展及其过程中的定量规律;串联在一根光纤上的多只FBG传感器能... 详细信息

深入分析了光纤布喇格光栅(FBG)裂缝传感原理,研究了基于FBG传感的分布式裂缝监测技术。为验证FBG裂缝传感的可行性,进行了混凝土模型试验发现,FBG能准确监测到裂缝发生和扩展及其过程中的定量规律;串联在一根光纤上的多只FBG传感器能进行分布式监测,在不知裂缝的具体位置和走向的情况下,能监测混凝土结构裂缝的发生和发展。

关键词：光纤传感器混凝土裂缝光纤布喇格光栅监测

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降雨滞后效应的数值模拟

水力发电学报 2010年第4期29卷 200-206页

作者：虞鸿包腾飞薜凌峰河海大学水文水资源与水利工程科学国家重点实验室南京210098 河海大学水资源高效利用与工程安全国家工程研究中心南京210098

降雨对绕坝渗流、土石坝的浸润线都有显著的影响。由于降雨影响具有非线性的滞后效应,缺少完善的求解理论,这在很大程度上影响了水工建筑物原型观测资料分析的准确性,限制了分析模型的预报功能。通过对降雨入渗坝体过程和坝体响应降雨... 详细信息

降雨对绕坝渗流、土石坝的浸润线都有显著的影响。由于降雨影响具有非线性的滞后效应,缺少完善的求解理论,这在很大程度上影响了水工建筑物原型观测资料分析的准确性,限制了分析模型的预报功能。通过对降雨入渗坝体过程和坝体响应降雨的效应进行分析,利用ADALINE网络对降雨的滞后效应进行数值模拟,并将模拟结果用于统计模型的建模分析,提高分析模型的准确性和预报能力。经过实际工程检验,数值模拟结果稳定,模型预报准确,可以广泛运用于大坝的资料分析。

关键词：水工结构降雨滞后效应数值模拟资料分析统计模型

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裂缝影响下碾压混凝土拱坝整体安全度评价

中南大学学报（自然科学版） 2013年第4期44卷 1479-1486页

作者：王少伟包腾飞徐波河海大学水文水资源与水利工程科学国家重点实验室江苏南京210098 河海大学水资源高效利用与工程安全国家工程研究中心江苏南京210098 河海大学水利水电学院江苏南京210098

以某碾压混凝土双曲拱坝为例,采用薄层单元模拟该坝拱冠梁处径向贯穿性裂缝,建立三维有限元仿真模型并进行非线性分析,研究有无裂缝2种情况下坝体的变位和应力状态,以及超载情况下拱坝地基系统各部位的屈服情况,综合评价裂缝对该拱坝整... 详细信息

以某碾压混凝土双曲拱坝为例,采用薄层单元模拟该坝拱冠梁处径向贯穿性裂缝,建立三维有限元仿真模型并进行非线性分析,研究有无裂缝2种情况下坝体的变位和应力状态,以及超载情况下拱坝地基系统各部位的屈服情况,综合评价裂缝对该拱坝整体安全度的影响。研究结果表明:各计算工况下,裂缝对坝体应力和位移的整体分布规律影响较小,2种模型下坝体的应力场和位移场基本相同,但有缝时裂缝端部附近会出现较为明显的应力集中现象,应采取加固措施以防止裂缝进一步扩展;超载时,2种模型下拱坝地基系统各部位的屈服情况基本相同,坝体材料按照线弹性分析时,2种模型超载整体安全度均为6.0左右,按照弹塑性分析时,整体安全度均为4.0左右。该拱坝径向贯穿性裂缝对拱坝-地基系统整体安全度无显著影响。

关键词：碾压混凝土拱坝贯穿性裂缝超载法整体安全度评价