The methane into the soil from buried natural gas pipelines due to small leakages, changes the soil properties, posing potential risks to humans and the environment. It is essential to estimate the leakage rate and monitor the methane diffusion range outside the pipeline, which is challengeable due to the presence of soil. The main contribution of this work is to bridge the gap between estimating the leakage rate of underground pipelines and predicting the diffusion behaviors through calculating the gas concentration in the soil. The quantified leakage rate estimation model for air was firstly established by experimental results and validated by the numerical results, which was further modified by the methane with the numerical simulations. The methane diffusion model in the soil was then performed, through which, the influencing factors were explained and validated. In addition, the methane release and dispersion results in the soil could be used as the boundary conditions of gas diffusion model in the air. The results show that the quantifying estimation correlations can predict the leakage rate and dispersion range in the soil accurately, with errors less than 7.2 % and 15 %, respectively. Moreover, the quantified relations have been validated by the full-field experiments. And, the dispersion behaviors in the air could be portrayed instead of being regarded as a jet flow.

由于泄漏量很小，甲烷从地下天然气管道进入土壤，改变了土壤特性，对人类和环境构成了潜在风险。估算泄漏率并监测甲烷在管道外部的扩散范围至关重要，由于土壤的存在，这具有挑战性。这项工作的主要作用是通过计算土壤中的气体浓度来弥合估计地下管道泄漏率与预测扩散行为之间的差距。首先通过实验结果建立了量化的空气泄漏率估计模型，并通过数值结果进行了验证，然后对甲烷进行了数值模拟修改。然后进行了甲烷在土壤中的扩散模型，通过该模型，对影响因素进行了解释和验证。另外，甲烷在土壤中的释放和扩散结果可以作为气体在空气中扩散模型的边界条件。结果表明，定量估计相关性可以准确预测土壤中的渗漏率和分散范围，误差分别小于7.2％和15％。此外，量化关系已通过全场实验得到验证。并且，可以描绘空气中的分散行为，而不是将其视为喷射流。结果表明，定量估计相关性可以准确预测土壤中的渗漏率和分散范围，误差分别小于7.2％和15％。此外，量化关系已通过全场实验得到验证。并且，可以描绘空气中的分散行为，而不是将其视为喷射流。结果表明，定量估计相关性可以准确预测土壤中的渗漏率和分散范围，误差分别小于7.2％和15％。此外，量化关系已通过全场实验得到验证。并且，可以描绘空气中的分散行为，而不是将其视为喷射流。