Abstract: This study intends to provide a more reliable theoretical basis for the laying of gas pipeline, parallel pipeline with gas pipeline and emergency-management decisions following accidental gas leaks. The porosity and the resistance coefficient of soil which are the key parameters of governing equations in soil were obtained by using the cutting ring method and a self-made experimental platform respectively. A physical model was built for leakage of gas from a buried gas pipeline. Effects of buried depth and leakage aperture on diffusion process of leakage gas in soil-atmosphere were investigated using a three-dimensional CFD model. The results show that the area of the dangerous zone in soil decreases first and increases afterwards with the increase of the buried depth, that the area of the dangerous zone increases obviously with the increase of cross-section of leakage aperture, that gas is easy to form accumulation in the ground of the street valley, appropriate buried depth is an important factor to reduce the area of the dangerous zone, that the parallel pipeline having a coupling danger with the existing gas pipeline should be laid along both sides of the street separately and that the cavity of the street is the most crucial area for emergency-management following accidental gas leaks.

Key words: buried gas pipeline, diffusion law, computational fluid dynamics(CFD) simulation, buried depth, leakage aperture