In Korea, damage from the collapse of artificial slopes along national highways has significantly decreased due to the continuous survey and preparation of measures for the last 17 years, while casualties and property damage from the occurrence of debris flow at the valley parts of natural mountain area have rapidly increased. Accordingly, the necessity of the debris flow management for natural mountain area that is similar to the artificial slope management has been suggested at a national level.
In this study, specific sections vulnerable to debris flow damage were selected, and a complete enumeration survey was performed for the sections with debris flow hazards. Based on this, the characteristics of the sections with debris flow hazards and the current status of actions against debris flow were examined, and an efficient installation plan for a debris flow damage prevention method that is required in the future was suggested.
The results indicated that in the Route 56 section where the residential density is relatively higher between the two model survey sections, facilities for debris flow damage reduction were insufficient compared to those in the Route 6 section which is a mountain area. It is thought that several sites require urgent preparation of a facility for debris flow damage reduction. In addition, a numerical analysis showed that for a check dam installed as a debris flow damage prevention method, distributed installation of a number of small-scale check dam facilities within a valley part was more effective than single installation of a large-scale check dam at the lower part of a valley.
In Korea, more than 70% of the territory consists of mountain area. Thus, formation of slopes depending on road construction was inevitable, and there were many unstable slopes along the roads that had been constructed during the rapid economic growth in the past. Accordingly, in case of concentrated rainfall in the summer season where more than about 60% of the annual precipitation occurs, small and large rock falls and landslides have continuously occurred. However, for artificial slopes along national highways, nationwide surveys and proactive measures have been prepared at a national level for the last 17 years, and thus, casualties and property damage from the collapse of artificial slopes have significantly decreased compared to the past.