///In Secondary disasters of “5·12” Wenchuan earthquake, two types of mountain hazards still have a great impact on road safety operation, one is unstably large rock body which heap on top of the slope; the second is low-frequency debris flow which have the high Outlet of low-frequency debris flow gullies that approximately intersect Minjiang River into the right angle. Their common feature is the dangerous source distributing in the high position, having large body, being ferocious, devastating impact. And coupling with their occuring time or space is uncertainty, resulting in inability of conventional control measures, and easily damaged. Open tunnel project is specifically made for the road hazard protection engineering. After pre-running, the open tunnel project have clearly demonstrated the superiority, but also exposed some areas needing further improvement.
