漏水聲波的特徵頻率

Abstract

供水管網系統是城市居民賴以生存與發展的基礎建設，自來水事業單位除積極的健全管網系統提高用戶用水品質外，更擔任維護保持安全及高效率供水重任，自來水管線一旦有漏水情形發生，將會造成水質、水壓、水量、供水連續性及安全性的影響且將亦遭受經濟、社會效益的損失。 國內目前對於自來水管的維護管理工作已朝向分區化、自動化的監測，但現行漏水點位的檢測定位仍仰賴經驗豐富及專業的檢測人員進行地毯式現地管線聽音為主，這樣的聽音辨位法會因主、客觀環境的干擾影響其判斷性及準確度。本研究以現地測錄疑似漏水點與另一比較點之聲音，先以兩聲波波形、平均均方根振幅進行初步分析，再以快速傅利葉轉換（Fast Fourier Transform, FFT)獲得頻譜圖後，利用高、低頻變化求得拐角頻率作為漏水聲波之特徵頻率內涵，並依據現地開挖後管線的實際狀態，來驗證聲波比較分析法對漏水點位判斷的準確性；最後本研究建立一分析判定流程作為爾後自來水管線進行檢測漏水時採用，以確定管線漏水存在與否，使未來漏水檢測工作邁向量化、合理化及科學化的範疇。

Water supplying pipe system is the basal infrastructure which all citizens rely on for living and developing. Tap water enterprise units do constructively integrate the completion of the system for improving the water quality, also assert and maintain the safety and the ability with effective water supplying. As long as leakages occuring in the water network, it will cause bad effects to the water quality, the pressure, the capacity, the continuity of water supplying, and the safety, on the other hand, it might cause the damage on economic and social benefit. The maintainence of water supplying pipes has been improved with the district area and auto monitoring. However locating leakage still need to depend on the experience of inspection engineers , who determine the leakage from listening the leakage noise using a leakage instrument. The accuracy of the listening method might be affected by subjective and site conditions. This research aims to present an approach to identify the leakage points by the spectra analysis of leakage noise recoreded from a leakage instrument. The approacch presented is as follows：First, the waveform and the root mean square of amplide recorded at a potential leakage point were compared with that at the point far away from the potential point. Then , the waveform in frequency domain for both waves was obtained by Fast Fourier Transform (FFT). The results of Fast Fourier Transform show that the corner frequency of leakage noise is about 500-600 hertz. Based on the results of spectra analysis and the results of imspecting the pipe in the dig hole, it can be find the the proposed approach is accurate enough for leakagedetecting.Finally,this research set up judge procedure for engineer to confirm the pipeline leaks or not. Hence, the leakage detecting using proposed approach will be toward to the quantificable, resonable and scientific category.