Study Of Soil Resistivity Response Law Under Leakage Intrusion Of Small Holes In Buried Gas Pipelines

Buried gas pipelines are subject to small-hole leakage due to electrochemical corrosion,which leads to various gas accidents.Therefore,the effective detection and timely disposal of buried gas pipelines become the key to maintain the safe operation of gas pipelines.In order to achieve the effective detection of small hole leakage location,the technical idea of using resistivity tomography to detect the change of soil in the leakage area to invert the leakage location is proposed,using a combination of theoretical analysis and laboratory experiments to study the change of soil morphology and resistivity response law of pipeline small hole leakage intrusion,analyze the influence of pipeline gas pressure and soil moisture content on resistivity distribution,and carry out preliminary field applications.(1)Improved the two-dimensional visualization of buried gas pipeline leakage monitoring system,which can carry out pipeline leakage experiments of 0.8m×0.04m×lm size and realize the monitoring and analysis of soil resistivity in the leakage area.(2)Carried out NMR experiments on gas-driven water in soil,analyzed the migration characteristics of water in soil using T2 spectra,and discovered the preferential airflow paths when gas is transported in soil.(3)conducted experiments on buried gas pipeline leakage under different conditions of pipeline gas pressure and soil moisture content,and found that the leakage of small holes of pipeline mainly showed two morphological characteristics of "tree" and "tree and gas bag co-existence" in the overlying soil;proposed a method to quantify the morphology of soil intrusion by using cavity area The method of using cavity area and canopy size to quantitatively characterize soil intrusion morphology was proposed,and it was found that pipeline gas pressure and soil moisture content have opposite influence on the intrusion soil morphology.(4)The resistivity changes of the soil before and after the leakage were analyzed by resistivity tomography,and it was found that the resistivity distribution in the leakage area also showed two characteristics:"tree" and "tree and gas bag co-existence",and the resistivity increase and decrease areas coexisted in the soil.The resistivity increase multiplier and increase area are positively correlated with the gas pressure and negatively correlated with the water content.(5)Preliminary research on the application of outdoor buried gas pipeline small-hole leakage was carried out,and it was found that with the growth of leakage time,the smallhole leakage intrusion area showed an obvious resistivity increase area,and the resistivity at the small-hole leakage was the maximum value,and gradually decreased along the vertical direction.Through the resistivity characteristics of buried gas pipeline leakage intrusion soil and the application of research,the preliminary formation of the use of resistivity laminar imaging method to detect the leak point,the results of the study is important guidance for the accurate detection of gas pipeline small hole leakage and the prevention of leakage accidents.Figure[54]Table[7]Reference[111]...