ABSTRACT
In mountain tunneling, construction works are in the proximity of tunnel faces where falling rocks and collapse of ground are often feared. It is however difficult to improve immediately such work environments, e.g. by applying full remote mechanized construction. In reality, a full-time watch guard stands in place and supervises safety at the tunnel face, when charging/connecting explosives and installing tunnel supports. When the guard judges that the continuation of tunneling work is in danger, he gives prompt warning to the workers, so they can immediately leave from the work area. A newly-developed face monitoring system utilizes an image recognition technology and a high-speed camera set beside the watch guard. It promptly catches fall of pebbles and flaked pieces of sprayed concrete as symptoms of possible tunnel face collapse possibly leading to disaster. It gives warning within a mere 0.1 seconds after the detection of movements of falling objects and gets the construction workers to leave immediately from the dangerous spot. The system has now been implemented in two projects. It is contributing to reducing workload from the tunnel face watch guard and to securing safety of the construction workers.
