大型混凝土输水管涵浇筑质量GPR检测研究

南水北调东线山东段穿黄河及小清河工程分别采用大型输水混凝土管道和箱涵形式。结构物浇筑质量采用具有无损检测能力的探地雷达方法（GPR）和超声波法进行检测。根据探地雷达（GPR）检测结果,分析了浇筑混凝土结构物中混凝土骨料集中、密实度不均;隐伏裂缝等缺陷及钢筋网分布状态的GPR图像典型异常特征。并基于GPR检测电磁波速和超声波速的对比,讨论了低含水率条件下GPR方法对混凝土强度的检测能力。     

探地雷达数值模拟技术在堤防工程安全检测中的应用

探地雷达检测具有简便、效率高和应用范围广的特点。在堤防工程病害检测中,以往雷达图像解释通常需要大量的试验和野外工作经验来相互验证,受各种条件的制约,使得检测工作效率下降。而利用数值模拟方法,对工程病害进行数值模拟计算,参照模拟结果进行对比解释,有助于病害判断,提高解释的准确性。本文通过对典型堤防工程病害的探地雷达数值模拟,为探地雷达图像识别提供了依据和经验。     

管道系统漏损控制技术进展

为了提高供水效率和运行管理水平,针对国内外关于供水管道系统漏损控制方面的现状,从管网故障监测技术及设备、泄漏定位模型方法、信号辨识与算法寻优、健康维护和智能管理等视角梳理了管道系统泄漏监测与漏损控制技术的进展及存在的主要问题,分析了各检测方法用于管网泄漏问题的适用性。在此基础上,从实用角度提出了管网漏损控制值得解决的关键问题和方向如下:(1)针对漏损的监测和预警,应研究面向漏损监控的管网网络组建优化布置及快速预警技术;(2)针对小泄漏的定位模型,应研究管网漏损区域辨识与基于水力反问题分析的主动检测理论和方法;(3)针对检测设备研制,应重点研发基于探地雷达、光纤传感和内窥机器人等新技术的关键设备;(4)针对管网健康维护和智能管理,应研究复杂管网独立计量区域划分方法及管网健康评价和优化维护技术。     

探地雷达检测的原理方法及在水利工程中的应用

本文介绍了探地雷达检测的基本原理、方法及检测过程中相关参数的选择,并结合实际工程,对所测探地雷达图像进行分析解释,结果表明,探地雷达检测技术不仅操作方便、检测效率高,而且其分辨率高,相对误差较小,值得在实际工程中大力推广应用。     

探地雷达在混凝土衬砌质量检测中的应用研究

文章通过分析探地雷达的原理,总结应用探地雷达进行现场质量检测的一些经验,指出了现场检测过程需要注意的事项,并利用南水北调试验段进行了探地雷达检测混凝土衬砌质量的现场试验。     

爆管抢修材料的应用技术

提高供水保证率是供水企业管理的服务宗旨,但在实际生产过程中,由于各方面的因素造成管道破损漏水不可避免;因此以最快速度修复漏损的输水管道,来保证安全输水尤其重要。文章就石棉水泥接口、膨胀水泥接口的优缺点及施工要点与管道快速抢修剂在爆管抢修及阀井漏水修补中的应用作一些经验总结。     

探地雷达应用于混凝土缺陷探测的试验研究

探地雷达具有高精度、快速、无损、经济的特点,在水利、建筑等工程的混凝土质量检测中得到一定的应用,但都只是辅助手段,无法推广。通过制作存在干碎石层、漏振等质量缺陷及埋设钢筋、PVC管的混凝土模型,应用探地雷达对这些模型进行了探测试验。结果表明:采用探地雷达可以较为明显地判断出混凝土中存在的漏振、干碎石层缺陷,漏振区在雷达图像上表现为错层,干碎石层在雷达图像上呈现出高亮反应;单层钢筋的探测效果比较明显,在雷达图像上呈现出三层高亮反应,但其直径分辨比较困难;双层平行钢筋和十字交叉钢筋在雷达图像上可以分辨,但较为困难;双层十字交叉钢筋在雷达图像上分辨不出来;探地雷达检测上层钢筋、下层PVC管的图像效果比较明显。     

供水管道泄漏点定位研究

针对目前供水管道探漏主要通过耳机进行人工听漏的缺陷,采用互相关分析法对输水管道进行探漏研究,试验表明泄漏量大小除了影响功率谱的幅度值外,对泄漏信号频率分布影响较小;对信号滤波处理时应根据所检测的管道类型设置合理的频带范围;在检测过程中,检测距离应控制在合理的范围内,不宜过长;传感器安装应避开阀门或接口,直接安装于管道的正上方。     

基于瞬变流频率响应分析的输水管道泄漏检测

采用传递矩阵法和频率扫描法,分析了管道泄漏对系统频率响应图的影响,以及频响图变化形态与泄漏点位置和泄漏面积参数之间的关系。在此基础上,介绍了基于管道瞬变流频响分析进行泄漏检测的步骤,并进行了数值试验验证。结果表明:1与完整管道相比,泄漏点的存在使系统频响图中各奇次谐波和偶次谐波的幅值均不再保持定值,而是随着谐波次数的不同呈现周期性的变化;2奇次谐波幅值随谐波次数周期性变化的主频率及相位反映了泄漏点位置,而该主频率所对应的幅值则反映了泄漏面积参数,据此可进行管道泄漏的检测;3数值试验结果表明基于瞬变流频率响应分析进行输水管道泄漏检测是可行的,且在泄漏孔面积占主管道面积比例较小的条件下,水锤波传播速度变化对检测结果的影响很小。     

地质雷达在古墙体无损检测中的应用研究

为了保护古城墙等重要遗产,尝试利用探地雷达技术检测古墙体.详细讨论了探地雷达检测古墙体的地球物理前提条件,就地质雷达在墙体无损检测领域开展了较深入的探讨,以正常墙体与存在隐患的墙体为对比,系统分析了墙体密实不均匀、局部脱空、裂隙的原因,总结了墙体常见缺陷的雷达波相特征,最后针对不同的异常做了详细的解释,为墙体检测及治理提供一定的科学依据.     

基于神经网络的管网漏失定位实例研究

为了在复杂且不直观的供水管网中快速实时定位漏点,以某城市区域管网为对象,在其上游、中游和下游各选取3条没有经过训练的管道,进行不同损坏程度的漏损模拟,利用BP神经网络可以逼近任意的非线性映射特点,将模拟数据作为训练样本训练神经网络,建立漏损点位置与测压点压力之间的非线性关系,构建基于BP神经网络的实时漏点定位模型。结果表明,模型预测的漏点位置横纵坐标的平均相对误差分别为4.16%和1.40%,预测的漏点偏移距离最小为6 m。当漏损面积比为0.01时,泄漏流量只有1 L/s,完全可以达到快速定位。此研究成果对实际管网的应用提供了理论基础和技术支持。     

ANALYSIS OF FIRST TRANSIENT PRESSURE OSCILLATION FOR LEAK DETECTION IN A SINGLE PIPELINE

The leak detection is of great importance in the reliable operation and management of a pipeline system. Recently,attention is shifted to the use of the time domain or frequency domain methods based on the transient analysis. These methodssometimes require accurate pressure signals obtained during the transient period or by creating ideal conditions in testing. This paperproposes a method that does not require transient simulations over the whole or an extended period of time, but uses the first transientpressure oscillation to detect leaks. The method considers the propagation of the pressure oscillation wave created from a fast valveclosure and the reflected damp wave from the leak. A leak in the pipe gives rise to reflected waves which in turn creatediscontinuities in the observed signal at the measurement section. The timing of the reflected damp wave and the magnituderepresent the location and the size of the leak, respectively. An analytical expression is derived based on the Method OfCharacteristic (MOC) for the relationship between the leakage and the reflected magnitude. The leak detection procedure based onthe method is also given. Then the reliability of the method is tested on numerically simulated pressure signals and experimentalpressure signals with calibrated leak parameters, and the results indicate a successful application and the promising features of themethod.     

Local and Global Leak Laws

The relationship between the functioning conditions of pipe systems and the leakage, or leak law, can be used at two different scales. At a local scale, i.e. for a single leak, it is derived from the classical orifice equation and, basing on experimental data, is modified to take into account all the relevant parameters it depends on (e.g., leak shape, pipe material and thickness, …). At a global scale, for a whole district or a part of a pressurized pipe system with several leaks, the same relationship is often used, basing on the assumption that the combination of local leak laws produces a similar global leak law. In this paper the effects of the spatial variation of the leak law parameters at the local scale on the leak law at a global scale are analyzed. Two leak laws derived from the orifice equation, the power law and the linear law, are considered. Results suggest that the global leak law exponent is larger than the corresponding mean local leak law exponent since it takes into account the spatial variability of the quantities affecting leakage.     

Experimental Evidence of Leaks in Elastic Pipes

Several studies have been carried out in recent decades to establish a relationship between total head and leaks. In literature, the leakage governing equations have been analysed in light of pipe materials, water head, leak dimension or shape. Most of these contributions questioned the classical Torricelli equation, demonstrating through experimental evidence that the classical orifice law can give unsatisfactory results. Nevertheless, starting from the Torricelli equation, other exponential or linear governing equations have been proposed as mathematical models able to reproduce the leakages in water distribution systems (WDSs). To investigate the validity of the proposed governing equations, an experimental campaign was carried out by means of a water distribution network composed of approximately 500 m of polyethylene pipes. The experiments were designed to investigate the effects of leak area and pipe rigidity on discharge. Furthermore, the effect of leak size enlargement with water head was analysed. Finally, the proposed research contributes to the population of a database for estimating the coefficients of head-discharge relationships.     

供水管网泄漏检测定位方法及仪器

本文研究了城市供水管道泄漏形成多相湍射流引发应力波在管壁中传播机理，分析了泄漏引发的管道横振、纵振和园环振动，提出了一系列和波特征提取指标及其离散数据算法、研究了以泄漏信号应力波时和频域特征指标构造神经网络输入和矩阵，建立了能对管道运行状况进行分类的神经网络模型，以检测管道泄漏故障的发生。研究了抗干扰管网泄漏定位方法，分析了根据管网不同特征对定位公式进行修正以提高泄漏定位精度的方法，实验研究了这一     

基于多尺度卷积神经网络的管道泄漏检测模型研究

如何有效检测管道泄漏是节水型社会建设迫切需要解决的关键和热点问题之一。近年来基于深度学习的管道泄漏检测方法发展迅速,本文针对传统单尺度卷积神经网络对泄漏特征提取不充分的问题,提出一种基于多尺度一维卷积神经网络(MS1DCNN)的管道系统泄漏检测模型。该方法利用多个不同卷积尺度的卷积通路并行提取管道泄漏的特征并进行泄漏信息的分类预测。基于经典的管道系统布置,利用瞬变流模型生成管道泄漏工况下的三个水压数据集对模型进行验证,三个数据集分别用于预测管道的泄漏位置、泄漏量和非恒定摩阻系数,对应样本数为39601、3980、4900,并将预测结果与其他深度学习方法和传统的机器学习方法进行对比分析。结果表明：MS1DCNN模型对数据集样本下泄漏位置、泄漏量、非恒定摩阻系数的分类准确率达到99.96%、98.48%、100%,三者平均预测精度比传统一维卷积神经网络(1DCNN)、BP神经网络、支持向量机(SVM)和k近邻算法(KNN)提高0.31%、2%、1.27%、22.8%;MS1DCNN在信噪比为-4～12 dB的噪声环境下各数据集的平均F₁分数分别为99.2%、97.02...     

An Accurate Leakage Localization Method for Water Supply Network Based on Deep Learning Network

In the water supply network, leakage of pipes will cause water loss and increase the risk of environmental pollution. For water supply systems, identifying the leak point can improve the efficiency of pipeline leak repair. Most existing leak location methods can only locate the leak point approximately at the node or pipe section of the pipe network but cannot locate the specific location of the pipe section. This paper presents a framework for accurate water supply network leakage location based on Residual Network (ResNet). This study proposes a leak localization idea with a parallel classification and regression process that enables the framework to pinpoint the exact position of leak points in the pipeline. Furthermore, a multi-supervision mechanism is designed in the regression process to speed up the model’s convergence. For a pipe network containing 40 pipes, the positioning accuracy of the pipe section is 0.94, and the MSE of the specific location of the leakage point is 0.000435. For the pipe network containing 117 pipes, the positioning accuracy of the pipe section is 0.91. The MSE of the specific location of the leakage point is 0.0009177. Experiments confirm the robustness and applicability of the framework.

     

Leakage Detection Using Smart Water System: Combination of Water Balance and Automated Minimum Night Flow

This paper presents a methodology for the application of the Smart Water technology to detect water leakage. This methodology consists in the use of the traditional water balance method together with the minimum night flow approach. This procedure has been applied to a large-scale pilot project conducted at the Scientific Campus of the University of Lille, which is the size of a small town. The water network of the campus is monitored by a set of sensors that record and transmit, in real-time, the hydraulic parameters of the water system. Analysis of real-time data has allowed the verification of water balance and the estimation of water losses level in the network. The paper presents an improvement of the application of the minimum night flow method, which is based on the determination of flow thresholds. A leak alarm is generated if the night flow exceeds the thresholds. This data analysis methodology provides the capability to detect the pipe bursts quickly, thereby reducing the runtime of leakage. The application of the improved method allowed the detection of 25 unreported leaks and decreased the Non-Revenue Water (NRW) level by 36%.     

旧有隧道隐伏病害GPR探测异常特征分析及病害程度评价

旧有隧道隐伏病害复杂多样,持续演变会对隧道结构与行车安全造成危害。虽然探地雷达技术(GPR)在隐伏病害调查中已应用广泛,但对GPR异常特征的认识并未统一,相应病害程度评价体系亦未建立。为进一步推动技术发展,归纳总结不同成因旧有隧道病害,建立相应介电模型,正演得到GPR理论图像并与工程实测图像对比,进行异常特征甄别;引入模糊数学的隶属度理论将多个因素进行综合评判,建立旧有隧道病害程度评判体系。研究表明:隧道衬砌裂缝和空洞会因填充介质不同,介电常数差异显著,多表现为同相轴错断或者局部性绕射增强的异常特征;衬砌非密实区和防渗层破坏区会持续发展成水-混凝土-残积物混合群块结构,具有多个反射界面,相应GPR图像波形杂乱,并伴有局部强反射。应用实例显示利用GPR诊测确定潜在病害区域后,在核定与旧有隧道隐伏病害相适宜的评价权重基础上,以建立的评价模型将多因素制约对象进行隶属度综合评判,能够较好地开展旧有隧道安全等级划分。     

供水管道渗漏状态下流量变化规律研究

通过管段渗漏模拟试验,分析了渗漏状态下供水管道流量变化规律。首先着重考察了压力和渗漏面积比对上游管段的转输流量的影响,试验数据表明上游管段的转输流量随着渗漏面积比的增大而增大,其增长趋势明显呈现S型曲线特征;不同压力作用下,转输流量的增幅存在显著差异。其次建立了渗漏量和转输流量之间的关系,渗漏量与转输流量的比值即渗漏强度呈线性关系增长,且随着压力增大而增大。最后分析了不同压力下渗漏强度与渗漏面积比的关系,结果表明渗漏强度随着渗漏面积比的增大而增大,且呈线性关系,实现了由渗漏面积比向渗漏强度的转化,以及用渗漏强度从流量的角度对供水管道渗漏程度进行描述。