埋地燃气管道泄漏扩散分析研究

Research on Leakage and Diffusion Analysis of Buried Gas Pipeline

摘要: 针对实际埋地燃气管道泄漏时天然气在不同类型土壤(沙土、黏土颗粒)及复杂地下空间(存在其他市政管道)中的迁移扩散规律不明确，给实际天然气工程管理及维护造成很大困扰。利用室内实验，系统分析研究了泄漏流量、泄漏口方向、泄漏点与扩散管水平/垂直距离、土壤表面覆盖等因素对扩散行为的影响及特征。分析发现：泄漏流量是主要驱动因素，流量增大会显著提升扩散速度、浓度累积范围和最终浓度(远距离测点反应同步明显)。土壤孔隙率是扩散模式的主要驱动因素，沙土(小孔隙率)中天然气横向扩散范围更大，但浓度累积较慢；黏土颗粒(大孔隙率)中扩散速度快但影响范围小，浓度梯度大。土壤不同类型对泄漏口方向的影响差异很大，沙土中开口向下可加速扩散并扩大影响范围，而黏土中开口向下则抑制扩散能力。与此同时，管道水平距离增加会大幅降低天然气向其它市政管道扩散的速度和浓度累积量；地表覆盖会阻碍天然气向上扩散，迫使横向迁移范围扩大，增加进入邻近密闭空间的风险。研究结果为燃气泄漏事故的预防、监测及应急处置等提供了有效的科学依据。

Abstract: The uncertain migration and diffusion patterns of natural gas in various soil types (sand, clay particles) and complex underground environments (including the presence of other municipal pipelines) during actual buried gas pipeline leaks pose considerable challenges to the management, maintenance, and emergency response of natural gas engineering projects. Through indoor experiments, we systematically analyzed and studied the impact and characteristics of various factors on diffusion behavior, including leakage flow rate, leakage port orientation, horizontal/vertical distance between the leakage point and the diffusion tube, and soil surface coverage. Our analysis revealed that leakage flow rate is the primary driving factor, with increased flow rates significantly enhancing diffusion speed, concentration accumulation range, and ultimate concentration (with notable synchronization at remote measurement points). Soil porosity emerged as the key determinant of diffusion patterns, with natural gas in sandy soil (characterized by low porosity) exhibiting a broader lateral diffusion range but slower concentration accumulation, whereas in clay particles (with high porosity), the diffusion rate is swift but the impact range is limited, resulting in a steep concentration gradient. The influence of soil type on leakage port orientation varies significantly. In sandy soil, a downward-facing leakage port accelerates diffusion and expands the scope of influence, whereas in clay, a downward-facing port inhibits diffusion. Furthermore, an increase in the horizontal distance from the pipeline significantly reduces the speed and concentration accumulation of natural gas diffusion towards other municipal pipelines. Surface cover hinders upward diffusion of natural gas, forcing it to migrate laterally over a broader range and increasing the risk of entering adjacent enclosed spaces. The findings of this research provide a solid scientific basis for the prevention, monitoring, and emergency response to gas leakage accidents.