Experimental Study On Electric Field Response Characteristics Of Gas Leakage In Composite Soil Pipeline

With the rapid progress of urbanization,the pipeline network layout of urban underground space is becoming more and more complex.As a part of underground pipeline network,natural gas pipeline plays an important role in the process of urban development and construction.However,it exist some characteristics after the natural gas pipeline leaks,such as large range of influence,strong hazard,flammability and easy explosion etc.Therefore,it is very important to detect and evaluate leakage of natural gas pipeline quickly and accurately.At present,technology for testing gas pipeline leaks is relatively lagging,and it is difficult to detect and locate leakage accurately.Therefore,on the basis of analyzing the current research status of the detection methods,combined with the burial characteristics of gas pipelines,the application of high-density resistivity method in leakage of pipeline gas is studied,these are as follows:1)By designing numerical models of different gas pipeline leakage types under composite soil conditions,the Earth Imager 2D electrical simulation software was used to select the working device for on-site measurement.After the gas leaked,an airbag cavity was formed around the pipe,and the cavity moved along the crack to the intermediate cavity of the soil layer and the leaking gas spread along the crack to the soil surface.The numerical simulation software simulate and calculate these three type of leak.The geoelectric field response characteristics of gas pipelines under different leakage conditions are revealed.The validity and reliability of this method in leakage detection of gas pipeline are illustrated.2)According to the situation that gas is easy to form air bag cavity after gas pipeline leakage,classified simulation is carried out.The numerical simulation is mainly based on the design model of different leakage pressure,different leakage location,different leakage directions and different leakage points.The simulation results show that the multi-electrode resistivity method has corresponding geoelectric field response characteristics in pipeline location identification and leakage location determination,which is basically consistent with the model design.3)In this paper,through building indoor physical model experiment,background field of pipeline leakage and the pipeline leakage situation under different pressure conditions such as 0.1 MPa,0.3 MPa and 0.5 MPa was tested by AM and ABM data acquisition methods.The results show that the apparent resistivity of gas pipeline increases with the increase of leakage pressure,and the results of the two data acquisition conditions are the same basically,which is highly consistent with the results of numerical simulation,It further proves the reliability and accuracy of multi-electrode resistivity method for detection of gas pipeline leakage.Figure[71] Table[3] Reference[83]...