Search

Different from the above ground pipeline, the soil characteristics and ground conditions have a great impact on the risk of leakage accident for buried natural gas pipeline. In this paper, the effects of ground conditions and soil characteristics on methane leakage and diffusion were studied by using numerical simulation. The two processes of methane leakage and diffusion, the methane leakage rate and the methane diffusion Early Warning Boundary (EWB) were investigated. Finally, based on the least square method and multiple regression theory, the calculation models of methane leakage rate and EWB were established. The results showed that: Compared with Unhardened Surface Ground (UHSG) condition, Hardened Surface Ground (HSG) increased the distribution of pressure, velocity and methane concentration in soil. The viscous resistance coefficient and inertial resistance coefficient of soil had a great influence on the methane leakage rate, while the ground conditions did not. Both ground conditions and soil characteristics had a certain impact on the EWB of methane diffusion. The average error of methane leakage rate direct calculation model was 4.48%, and the average error of EWB calculation model under HSG and UHSG condition was 3.59% and 7.77% respectively. The methane leakage rate and the EWB calculation models suggest the soil characteristics as independent variables and can provide the rapid calculation of leakage rate and EWB under any soil characteristics without the help of computer iterative solution. The methane leakage rate direct calculation model makes up for the vacancy of calculation method of leakage rate of buried pipeline under different soil characteristics.