基于土-管-水耦合作用的供水管道主动式声学泄漏检测方法研究

City water supply pipe networks are of most paramount importance for maintaining a substantive modern life and economic development. Underground pipes are susceptible to leakage resulting in severe accidents, due to excavation damage, sabotage, deterioration and aging. Cross-correlation methods based on the low-frequency characteristics of the leak noise have been widely used for the detection of water leaks. Pervious work on the correlation measurements has shown that water leaks can be successfully detected at ranges up to 1 km in metal pipes and 100 m in plastic pipes. In practice other considerations that affect the efficacy of the established methods are due to the nature of small leakage and presence of the pipe connections. An investigation into acoustic leak detection method based on the soil-pipe-water coupling effect under excitation will be carried out in order to develop a new technique for the detection and location of water leaks. Theoretical model of wave propagation due to water leakage is first established, and an approach for predicting the ground surface response resulting from the radiated elastic waves in the soil medium is subsequently developed. Combined with numerical simulations, the influence of pipe discontinuities on wave propagation in the coupled pipe system is studied. Experimental measurements will be conducted along with numerical validation in order to corroborate the theory. Two pipe systems will be developed, including the PE water pipe in the laboratory and cast iron water pipe on site. The excitation method will be tested, from which the wave propagation behaviour along the pipe will be addressed explicitly; and the water leak detection technique based on the pipe vibration and ground surface vibration will finally be proposed and tested. Theoretical modelling is also applicable to gas and oil pipes. The findings of the proposed work will provide the basis for the detection and location of small leakage and multi-leaks in water distribution pipes.

城市供水管网是保障人民生活和经济建设的必要基础设施。由于管道的劣化、老化、自然灾害和建筑施工破坏等原因，管道泄漏以及引发事故频频发生。基于低频段泄漏声信号的相关检漏法在埋地供水管道泄漏检测中使用最为普遍。然而该方法在金属管道中测距为千米，塑料管道的测距仅为百米。本研究基于土-管-水耦合作用的主动式声学检测方法是一项崭新的研究课题，基于波动法建立泄漏声在埋地供水管道中传播的理论模型，提出声波向周围介质辐射引起的地面振动响应的分析方法，结合数值方法、仿真模拟揭示管道突变点对声波的影响变化规律。通过实验室PE充水管道和现场铸铁供水管道实验对提出的理论模型和研究方法进行验证和完善，揭示主动式激励所激发声波沿管道传播的变化规律，建立基于管道振动与地面振动的主动式声学泄漏检测及定位方法。研究成果为实现小泄漏量、多泄漏源的管道检测与定位提供关键技术支撑，为声学法在油气管道的推广应用奠定基础。

本项目通过理论分析、数值仿真、实验室PE充水管道实验、现场塑料管及铸铁供水管道实验相结合，开展了基于土-管-水耦合作用机理的管道泄漏检测和定位的理论、方法、装置研究。主要成果归纳如下：（1）建立了土-管-水耦合系统中管道泄漏声波的低频传播理论，提出了轴对称s=1波的频散关系的求解方法，给出了其复波数的解析解表达式；（2）进一步根据地表自由边界条件，推导出由于管道泄漏所引起的地表振动响应的表达式，阐明了典型砂土中辐射弹性波的干涉现象。通过埋地供水管道实验和数值仿真验证了理论模型。（3）基于充液管道泄漏声信号的低频传播特性及辐射机理，提出了四种新的管道泄漏检测与定位方法：基于导数广义互相关（DIF-GCC）的时延估计算法; 自适应相位谱（ADPHAT）时延估计算法；基于PVDF线圈传感器的管道泄漏检测方法；基于传感器阵列成像的泄漏平面定位方法。完成了一系列实验室和现场埋地供水管道的泄漏检测实验验证工作。本项目丰富和发展了土-管-水耦合系统中声振特性的理论，为管道泄漏检测和定位提供新的思路与研究方法。

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