Research Of Leakage Positioning Method Of Landfill Based On Optical Fiber Microbend Loss

Landfills,as an important final disposal means of domestic waste and hazardous solid waste,are widely used in various kinds of landfill sites.After the landfill,the high concentration organic wastewater is formed due to the degradation,acidification and fermentation of the waste.High density polyethylene(HDPE)can prevent landfill leachate from crossing and then protect the underground environment from pollution.But in practical application,it is found that HDPE film will cause damage due to human or natural factors.At present,almost all landfill seepage prevention layers have leakage problems.If leakage is not detected and repaired in a timely manner,landfill leachate will enter the soil through the pores or leak into the surrounding environment,causing potential environmental health and safety risks.Therefore,it is of great significance to discover and locate leakage in a timely and accurate way for environmental protection and restoration.At present many new landfill with bentonite waterproof blanket(GCL)instead of clay layer,detecting and locating method of high voltage direct current mainstream traditional method is no longer applicable,because the need to have the thick clay layer is then laying power and detection electrodes,and the thickness of GCL in millimeters.In view of the above landfill leakage problem,this paper proposes a new positioning method based on optical fiber micro bend loss principle and optical time domain reflectometry technology.The landfill leakage of active and real-time monitoring and can in a short time monitoring of seepage occurs,which can timely and accurately detect and repair the leakage location and reduce leachate on Soil and water environmental pollution and harm to maximize.The main work of this article is as follows:Firstly,this paper introduces the existing landfill leakage detection situation and on the basis of a brief analysis of the advantages of optical fiber sensing technology,on the basis of using OTDR design leakage detection and location system,and analyzes the working principle and the performance of the detection system parameters.Based on the in-depth analysis of the principle of optical time domain reflectometry technology,the related factors that affect the dynamic range and spatial resolution of the system are discussed,and a simple coding scheme for signal detection is proposed,combined withmatrix operation and signal processing.Then,a new pulse detection method based on monopulse and adding a simple encoding pulse as a new detection signal is proposed,which is used to improve the dynamic range of the detection system.The basic principle of simple coded optical time domain reflection detection is analyzed,and the generation and demodulation of simple coding are calculated by matrix operation.In view of landfill detection system,MATLAB simulation software is used as a simulation model based on the simple coded optical time domain reflectometry technology,and compared with the traditional single pulse optical time domain reflectometry technology.Finally,a detection platform is built on the basis of simple coded optical time domain reflectometry(TDR).In the detection of optical fiber micro bend loss,the influence of different pulse width and different coding order on the dynamic range and positioning accuracy is compared.The parameter setting of the landfill leakage detection system based on the optical fiber micro bending loss and the contrast detection scheme for improving the positioning accuracy and reliability are determined.