Die Vertiefungen waren geringer in Blöcken mit hoher Gesteinshärte. Die Gesteinshärte in allen Gesteinsblöcken wurde mit dem Equotip Härtemessgerät bestimmt. Die größten Tiefen in den einzelnen Gesteinsblöcken wurden 1971, 1989, und 2001 gemessen und sie korrelieren mit dem Zeitraum von 20, 38 und 50 Jahren nach dem Brückenbau. Die Sandsteinverkleidungen zeigen tafoniähnliche Vertiefungen als Ergebnis der Salzverwitterung und der Wellenerosion. Die Basis der Pfeiler liegt im Tidenhub (mittlerer Tidenhub 1,6 m) und die Seitenwände haben eine Höhe von 3 m. The depth of depression, D, was described as a function of the salt weathering susceptibility of sandstone blocks Ws, the height above mean high water level h (m) located the blocks, and time t (years) D = 68.6 (Ws) e−0.0038 h (1−e−0.031 t) where Ws = P/St (P is the total potential pressure of salt crystallization generated in unit volume of the rock, and St is the tensile strength estimated from Equotip hardness).ĭie Yayoi Brücke, die die Aoshima Insel mit der Kyushu Hauptinsel in Japan verbindet, hat vier sandsteinverkleidete Pfeiler. These data showed that the depth of depressions was smaller in the blocks having larger strength. Rock strength in all sandstone blocks was also measured using an Equotip hardness tester. The greatest depth of each depression in all blocks was measured in 1971, 1989, and 2001 corresponding to 20, 38, and 50 years, respectively, since the construction of the bridge. Each sandstone block has developed a tafoni-like depression in all blocks due to salt weathering and wave erosion. The base of the piers are situated at Mean Tide Level (mean tidal range: 1.6 m), and the side walls of the piers have a height of 3 m. Human stupidity has no border.Yayoi Bridge, connecting Aoshima Island with Kyushu main island in Japan, is supported by four piers whose surface is composed of sandstone blocks. We notice that similar facts have been already whitnessed in France, in Fontainebleau with “The Alchemist” or with the traverse of “Scarabée” or in Chamonix with “Kaiser Sauzé”. Dai is especially dismayed because he had a great project on this piece of rock, “Natori”, also broken, a boulder that he considered a new level of difficulty higher than what had been established in Japan, and a challenge for future generations. The passages like “Nehanna” 8C among others have also been damaged. Indeed several holds of the boulder were destroyed, presumably by crowbar or hammer. Stupor, sadness and misunderstanding are the feelings that animate the Japanese legend Dai Koyamada who had the bad surprise to discover this week that his boulder “Nayuta” 8C + opened in Gero in April 2017 had been vandalized. On rappelle que des faits semblables se sont déjà produits en France, à Fontainebleau avec “L’alchimiste”, la traversée de “Scarabée” ou encore à Chamonix avec “Kaiser Sauzé”. Dai est surtout atterré car il avait un super projet sur ce pavé, “Natori”, un bloc qu’il jugeait d’un niveau de difficulté supérieur à ce qui avait été établi au Japon, un challenge pour les générations futures, lui aussi endommagé. Les autres passages du bloc “Nehanna” 8C entre autres ont été aussi abîmés. En effet, plusieurs prises du bloc ont été détruites, vraisemblablement au pied de biche ou au marteau. Stupeur, tristesse et incompréhension sont les sentiments qui animent le japonais Dai Koyamada qui a eu la mauvaise surprise de découvrir cette semaine que son bloc “Nayuta” 8C+ ouvert à Gero en avril 2017 avait été vandalisé.