Construction access roads, as temporary facilities, are essential in mountainous road construction. However, the drainage issues or structural failures of these roads can easily lead to changes in surface runoff. This study analyzes the relationship between the collapse of construction access roads due to poor drainage during heavy rain and the flooding of downstream industrial areas, based on actual cases, on-site inspections, data analysis, and theoretical calculations. The disaster-causing ratio resulting from the collapse of construction access roads is also obtained, providing reference for similar projects.

construction access road, flood peak flow, slope gradient, breach, superposition effect, disaster ratio

施工便道作为临时设施是山区道路施工过程中必不可少的环节，施工便道泄水功能缺陷或结构失效极易造成地表径流变化。通过工程实际案例，结合现场勘验、资料分析及理论计算，对暴雨条件下施工便道因排水不畅出现溃决与下游厂区被淹进行关联分析，并推导施工便道溃决的致灾比例，供参考。

施工便道, 洪峰流量, 坡降, 溃决, 叠加效应, 致灾比例