Research results

For a New Method of Designing Road Disaster Prevention Structures
- Safe and secure road network -

Road disaster prevention structures

Experiment on a model rock-shed on a scale of two-fifths actual size

Weight impact test with a steel weight
(W = 10 t) simulating a rockfall

Japan has precipitous terrain with about 70 percent of its territory covered with mountains and hills, complicated geology and soil properties with earthquakes occurring frequently and other harsh environmental conditions including typhoons, rainfall and snowfall. Under the circumstances, protecting the lives and property of people from natural disasters is a most fundamental issue. These disasters include debris flows, landslides and slope failures and they have occurred on average at least 1,000 times a year for the past ten years (1999 to 2008), causing tremendous damage (source: White Paper on Ministry of Land, Infrastructure, Transport and Tourism in Japan 2009). Of the victims of natural disasters, those of slope disasters account for a large proportion.
Not a few roads in Japan are built through areas with precipitous terrain and coastlines and there have been frequent large-scale rock mass failures and slope failures including rockfalls. This situation has created an urgent need for research and development to improve road disaster prevention standards. CERI has been conducting studies especially on road disaster prevention structures (such as rock-sheds and rockfall retaining walls) to propose a new rational method of design.
Based on the experiments and analyses conducted up to now, it has been confirmed that road disaster prevention structures built using the conventional design methods have sufficient levels of safety against assumed rockfall loads. On the other hand, locations with disaster factors exceeding the assumed rockfall loads because of factors such as secular change of slopes, are sometimes found by inspection. Given this situation, it has become necessary to gain an understanding of how much rockfall impact energy can be withstood if the assumed rockfall loads are exceeded.
To address this issue, the Structures Research Team has been conducting joint research with the Muroran Institute of Technology. In this research, we have made a large model in our test field and carried out weight impact tests with a steel weight simulating a rockfall. The aim is to find out the extent of damage to road disaster prevention structures caused by rockfall impact and to establish an analysis method that allows rockfall impacts to be accurately reproduced.

(Contact: Structures Research Team, CERI)