• Tunnel and Underground Space
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• v.20 no.3
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• pp.194-206
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• 2010

It has been presumed that Bangudae-petrogram and Chunjonri-petrogram have been sculptured along the river Taewha in the prehistoric age. These petrograms have been sculptured on shale, the sedimentary rock of cretaceous in Mesozoic era and have been weathered by wind and rain for around 6000 years, resulting in weathering grade 5. Specially, Bangudae-petrogram has been in submerged zone in Sayeon dam for 168 days a year and the submersion has been repeated for 45 years up to date. This paper adopts an engineering approach to these petrograms' properties and discuss how to enhance strengths of petrograms themselves and stop weathering.