Sewer Condition and Blockage Detection Classification Using Novel Acoustic Instrumentation

在英国，下水道系统正在老化，监控不力，长约30万公里。由于城市化进程加快、环境法规更加严格以及气候变化带来的降雨更加频繁和强烈，该系统的容量需求不断增加。OFWAT是水务行业的经济监管机构，它规定水务公司有法律的义务维护其下水道系统的结构和运行条件，并逐步减少下水道的洪水事故。2004年，OFWAT确定了5700起下水道洪水事件，另有11600处房产每年有10%的洪水风险。在这些个案中，约有90%是由于污水管阻塞而引致水浸。因此，监测管道是否有阻塞物，然后迅速将其清除，可以成为减少下水道泛滥的有效方案的重要组成部分。该项目的目的是开发新的声学技术（传感器和软件），以生产一个接近市场的原型，可用于活下水道，以快速，客观地测量管道状况，并确定堵塞和损坏。下水道监测目前仅限于解读闭路电视图片或使用LightLine调查。这些方法需要插入带有摄像机的移动的小车，并沿管道段向上行进，获取图像，然后根据标准下水道修复手册文件手动检查图像并对缺陷/障碍物进行分类。与英国下水道运营商的讨论表明，他们每5年对大约2%的网络进行CCTV调查。该项目将开发一种替代的快速方法，用于客观分析下水道的状况和定位堵塞。布拉德福德大学最近的研究（EPSRC授权EP/D 058589/1）已经证明，可以使用声学检查方法在实验室管道中测量管道堵塞面积、裂缝范围、水位和横向连接位置。通过这种方式，可以确定下水道的管道状况在空中区域的人孔之间。该声学设备的关键要素是一个小型的多传感器阵列和先进的实时信号处理算法，它克服了环境噪声和混响的影响，在沙井环境。向商业部门转让这一技术的主要障碍是：（一）建造一种本质安全、坚固的仪器;（ii）取得足够的实地数据，向准使用者清楚显示声波传感器能可靠地识别污水渠的毛病和梗阻证明声学技术可以提供与传统CCTV方法兼容的数据，并可以映射到现有的下水道状况英国水务公司使用的分类和下水道数据库。现场收集的数据对于确定工业资金的性质和范围以及潜在利益相关者的商业利益至关重要。调查人员正在与支持这项工作的四个商业组织接触：理查德·朗协会、穆切尔·帕克曼、约克郡水务公司和泰晤士水务公司。一般认为，闭路电视测量每100米长度需要2至4小时进行测量，图像分析时间相似。这取决于出入的限制，费用在每延米2至40美元之间。声学测量潜在地将测量和分析时间减少到每100米几十分钟。可以实现显著的效率。这将使运营商能够更频繁地对其网络进行更多的调查，从而可以制定更好的监测策略，更早地发现缺陷，特别是堵塞，从而减少洪水事件并更好地计划维护。

In the UK, the sewer system is ageing, poorly monitored and around 300,000 km long. The system is subject to increasing capacity demands because of increased urbanisation, more stringent environmental regulation and the consequences of climate change in the form of more frequent and intense rainfall events. OFWAT, the economic regulator for the water industry, imposes a legal duty on water companies to maintain the structural and operational conditions of their sewer systems and also to progressively reduce flooding incidents from sewers. In 2004 OFWAT identified 5700 sewer flooding incidents and an additional 11600 properties with a 10% annual risk of flooding. In approximately 90% of these cases, flooding was caused by an obstruction in a section of sewer pipe. Consequently, monitoring pipes for obstructions and then rapidly removing them could form an important part of an effective programme to reduce sewer flooding. The aim of this project is to develop novel acoustic technology (sensor and software) to produce a near market prototype that can be used in a live sewer to measure rapidly and objectively in-pipe condition and identify blockages and damage. Sewer monitoring is currently limited to the interpretation of CCTV pictures or the use of LightLine surveys. These methods require a mobile trolley with camera to be inserted and travel up a pipe section acquiring images which are then manually examined and defects/obstructions classified according to the standard Sewer Rehabilitation Manual document. Discussions with sewer operators in the UK indicate that they CCTV survey around 2% of their networks every 5 years. This project will develop an alternative fast method for analysing objectively the condition of a sewer and locating blockages. Recent research at the University of Bradford (EPSRC grant EP/D058589/1) has proved that the area of pipe blockage, extent of cracks, water level and positions of lateral connections can be measured in the laboratory pipes using an acoustic method of inspection. In this way the pipe condition of a sewer could be determined between manholes in the airborne regime. The key element of this acoustic device is a small multi-sensor array and advanced, real-time signal processing algorithm which overcome the effects of ambient noise and reverberation in the manhole environment. The key barriers to transferring this technology to the commercial sector are: (i) construction of an intrinsically safe, robust instrument; (ii) acquisition of sufficient field data to demonstrate clearly to potential users that acoustic sensors can reliably identify defects and obstructions in sewers (iii) demonstration that the acoustic technology can provide data that is compatible with the conventional CCTV methods and can be mapped onto the existing sewer condition classifications and sewer databases used by UK water companies. The data collected in the field will be critical in determining the nature and extent of the industrial funding and commercial interest from potential stakeholders. The investigators are in contact with four commercial organisations who support this work: Richard Long Associates, Mouchel Parkman, Yorkshire Water Services and Thames Water. It is generally agreed that CCTV surveys take between 2 and 4 hours per 100m length for measurement with a similar time for image analysis. This costs between 2 and 40 per linear metre depending on the access constraints. Acoustic measurement potentially reduces the measurement and analysis time to tens of minutes per 100m. Significant efficiencies can be achieved. This would enable operators to survey more of their network more frequently so would allow for better monitoring strategies to be developed, the earlier identification of defects and especially blockages leading to fewer flooding incidents and better planned maintenance.