为研究浅埋隧道中烟气逆流长度的影响因素，以武汉东湖隧道为工程背景，采用量纲分析法，构建竖井排烟隧道内火源上游烟气逆流长度无因次表达式，并通过数值模拟，量化研究火源热释放速率、纵向送风风速、竖井与火源距离、竖井宽和高对火源上游烟气逆流的影响。结果表明： 上游烟气逆流长度随火源热释放速率、竖井与火源距离增长而增大，但当超过一定值时，烟气逆流长度均趋于稳定； 随着隧道纵向风速和竖井宽度的增加而减小，且不受竖井高度变化的影响； 同时，火源热释放速率与纵向风速的影响明显强于其他因素。创新性推导出了考虑火源热释放速率、纵向送风风速、竖井与火源间距、竖井宽度情况下火源上游无量纲烟气逆流长度的预测公式，且与数值模拟结果良好吻合。

In order to explore the influence of vertical smoke exhaustion shaft of urban shallow tunnel on smoke backlayering flow at upstream of the fire source, dimensional analysis method is used to establish the dimensionless expression of smoke backlayering flow at upstream of the fire source in Donghu Tunnel with vertical smoke exhaustion shaft; and numerical simulation method is used to study the influences of the heat release rate (HRR), longitudinal ventilation velocity, distance between shaft and fire source and the width and height of the shaft on upstream smoke backlayering flow. The results show that: (1) The upstream smoke backlayering flow length increases with the increase of HRR and the distance between the shaft and the fire source, and it becomes stable when reaches a certain value. (2) The upstream smoke backlayering flow length decreases with the increase of tunnel longitudinal ventilation velocity and shaft width; (3) The shaft height does not affect the upstream smoke backlayering flow length . (4) The HRR and the horizontal ventilation velocity affect the upstream smoke backlayering flow length more obviously than other factors. Moreover, a formula is innovatively deduced to predict the dimensionless smoke backlayering flow, which comprehensively considers the effects of the HRR, longitudinal ventilation velocity, distance between shaft and fire source and shaft width, and whose results are coincide with the numerical simulation results well.