Japan Atomic Energy Agency has been constructed the Underground Research Laboratory in Hokkaido. In the shaft excavation, length, direction and aperture of geological observation are measured and analyzed in order to estimate rock permeability around lining. In this report, correlation between frequency of cracks and rock permeability based on crack tensor and stereology was discussed. Prediction equation of rock permeability from the frequency of cracks on the shaft wall was also proposed.

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 The present paper indicates that effects of smoke extraction by ventilation system in road tunnel fires, which model tunnels adopted urban U-shaped tunnels shorter than 500 m length. The investigation used smoke CFD simulation and evacuation simulation. In the case with natural ventilation velocity 1.2 m/s, the situation where it difficult for over 10 users to evacuate due to exposure by smoke occurred with no smoke extraction by ventilation facilities. Meanwhile in the case with over 0.3 m³/s·m of smoke extraction by ventilation facilities, smoke propagation can be controlled even with natural ventilation existing, the number of users exposed by smoke decreased from 3 persons to 0. Hence, it was confirmed that even in short tunnels smoke extraction by ventilation facilities was necessary to keep the users' evacuation safety in tunnel fires.

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 A catastrophic accident involving road users occurred at Sasago tunnel built in Yamanashi prefecture in December 2012. In Japan, many infrastructures have been constructed have contributed to economic growth, but recently one of the most challenging issues is to know whether these old infrastructures are safe or not, and the inspection to evaluate their soundness will play an important role. Considering these situations, this study proposes a new mobile inspection method using a vehicle with laser scanners and image photographing units as a robot technique introduced to the inspection work. In this paper, the authors discuss the latest management criteria and problems about maintenance for road tunnel, and consider the feasibility of our proposed inspection method. We present the importance of maintenance work by utilizing the robot technique to make maintenance work more efficient, more accurate and safer.

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 The devastation caused by the Great East Japan Earthquake of 2011 has taught us, once again, the importance of taking measures in advance to prevent foreseeable disasters. In Europe, an EU directive was issued after a major tunnel fire, and member states have enacted and are implementing stricter tunnel safety standards. And the accident at Sasago tunnel in 2012, has reasserted the importance of putting “safety first.” With progress in simulation technology to reproduce tunnel fires accurately, it is now possible to identify potentially high-risk tunnels before fires occur. Our study on the current issues and their countermeasures are reported in this paper.

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