土壤地下空间耦合下天然气泄漏扩散数值模拟

随着燃气管道数量和规模的增加，由于燃气泄漏至相邻地下空间导致燃气爆炸的事故日益突出。为了研究天然气管道泄漏后气体在土壤和地下空间耦合下的扩散过程及规律，本文采用COMSOL软件中建立燃气管道泄漏在土壤和阀门井中扩散的数学模型，分别研究不同管道压力、土壤孔隙率、泄漏口到阀门井水平距离对燃气泄漏扩散的影响，结果表明：随着管道压力和土壤孔隙率的增加，阀门井内甲烷摩尔分数到达爆炸下限的时间相应减小；不同孔隙率条件下阀门井内甲烷摩尔分数差值逐渐稳定在一个定值；泄漏位置距离地下空间小于12.5 m时，阀门井内甲烷摩尔分数到达爆炸下限的时间小于7天，距离大于12.5 m时阀门井内甲烷摩尔分数到达爆炸下限需要一周以上的时间。

Numerical Simulation of Natural Gas Leakage and Diffusion in Soil and Underground Space Coupling

With the increase of the number and scale of gas pipelines, the accident of gas explosion caused by gas leakage to the adjacent underground space has become increasingly prominent. In order to study the process and law of gas diffusion under the coupling of soil and underground space after natural gas pipeline leakage, the mathematical model of gas pipeline leakage diffusing in soil and valve well is established by using COMSOL software. The effects of different pipeline pressure, soil porosity and horizontal distance from leakage mouth to valve well on gas leakage diffusion are studied by it respectively. The results show that: with the increase of pipeline pressure and soil porosity, the time for the mole fraction of methane in the valve well to reach the lower limit of explosion is correspondingly reduced; Under the condition of different porosity, the difference value of the methane mole fraction in the valve well gradually stabilizes at a fixed value; When the leakage position is less than 12.5 meters from the underground space, the time for the mole fraction of methane in the valve well to reach the lower limit of explosion is less than 7 days. While it takes more than a week for that when the distance is more than 12.5 meters.