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Title |
The Stability Assessment of ASSM Tunnels in Service
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Keywords |
ASSM ; 반발경도법 ; 라이닝공동 ; GPR ; 균열 ; ASSM ; Rebound method ; Linning cavity ; GPR ; Crack |
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Abstract |
The need of securing the stability and extending service lives by efficient maintenance of deteriorated tunnels for several decades has been increased. The stability and the usability of conventional tunnels can be decreased by change of physical properties of the surrounding ground, geometrical properties of the tunnel, an underground water level, environmental conditions, oxidation of lining and the breakdown of constituent materials. In respect of a long-term view, it is need to check all sorts of degradation, the degree of damage and durability to improve the serviceability and to come up with measures to maintain effectively. This paper is about study to analyze the stability of conventional tunnels(American Steel Support Method. ASSM). Three tunnels are chosen in those built in the 1930s and 1960s and the locations of tunnels are selected variously(ChungCheong, GyungBuk, GangWon, Jeolla, etc.) to secure reliability of this study. The state of repair and reinforcement of linings, cracks, and thickness and strength of lining of conventional tunnels in service are researched, compared and analyzed. The crack gauge, the GPR, the schmitt hammer was used for the crack investigation, cavitation, the strength respectively. By using these, the comparative analysis for conventional tunnels was conducted. As a result, there are more cracks in tunnels built in the 1930s than those of tunnels built in the 1960s, and lining strength of the 1930s is higher than those of the 1960s. The thickness of lining in tunnels built in the 1960s is higher than those in tunnels built in the 1930s. In proportion to thickness, cavitation occurred more frequently in tunnels built in the 1960s compared to those in tunnels built in the 1930s.
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