ABSTRACT
Slope failure during or immediately after slope-cutting can cause fatal accidents. This study analyses the characteristics of labour accidents caused by slope failure during slope-cutting in Japan and presents a countermeasure to prevent accidents caused by slope failure, such as the implementation of a slope guideline by MHLW. A case history conducted during slope-cutting and nailing was presented as an example of the application of the slope guideline to ensure safety. Furthermore, monitoring methods were implemented to gain a quantitative understanding of slope deformation. Geological conditions other than those assumed prior to excavation and small collapses attributed to groundwater are indications of landslide risk. The guideline's quick checklist reflects the slope condition or deformation, allowing the client, designer and contractor to discuss and agree on a quick solution to a problem. The case study confirmed the effectiveness of the slope guideline as a tool for sharing information during construction.
ABSTRACT
In February 2012, a serious accident which resulted in five fatalities happened during a TBM-tunnel construction under the seabed in Japan. The cause of the accident appeared to be due to the Key-segment slipping out of the segment ring by the thrusting tailskin (wire brushes) of the TBM into the segment ring. This resulted in the collapse of the rings, causing the seabed ground and seawater to flow into the tunnel. We investigated how thin and thick segments without any circumferential joints behave under isotropic and anisotropic pressures using small-scale physical model. In the model tests, pressures were applied to the surroundings of the segment rings and the strains at each segment were measured in order to evaluate the damage. In addition, cases where lubrication on the contact area between the K- and B-segments was present or not were investigated and their discrete element simulations were also conducted.
