Mountain railroad tunnels often need to cross deep and large active fracture zones during construction and tunnel site areas can be crisscrossed with underground water systems that carry huge volumes of water. The risk of sudden water inrush during the construction of mountain railroad tunnels is high, and uncontrolled inrush water runoff can negatively impact the tunnel site area. Therefore, risk assessments and prevention of inrush related surface runoff damage is key to reducing the ecological impact of tunnel construction. In this paper, the inrush water runoff of a typical mountainous railroad tunnel in the southwest of China was taken as the research object and the hydrological model and hierarchical analysis (AHP) were used to build a comprehensive risk assessment algorithm for surface runoff. Then the risk level of each section of the runoff channel was assessed under different flow scenarios and different inrush water runoff environmental risk prevention measures were proposed.

山区铁路隧道在施工过程中经常需要穿越深大的活动断裂带，隧道场地区域可能与承载大量水的地下水系统纵横交错。山区铁路隧道施工过程中突然突水的风险很高，不受控制的突水径流会对隧道场地面积产生负面影响。因此，风险评估和预防与突水相关的地表径流损害是减少隧道施工生态影响的关键。本文以西南地区典型山区铁路隧道突水径流为研究对象，采用水文模型和层次分析法（AHP）构建地表径流综合风险评估算法。然后评估不同流量情景下径流渠道各断面的风险水平，提出不同的突水径流环境风险防范措施。