Peculier failures have been observed in asphalt pavement at the Chitose Airport. The main failures are deflections and erosions of the asphalt surface after a single winter exposure. The damage to asphalt has been attribute to disintegration of the altered andesite aggregate used. Since the rock itself does not weather rapidly, the only chemical process that might produce to known effect would be an interreaction between ethyleneglycol in deicing fluid and montmorillonite in aggregate. Aggregate is put into a state of internal stress as it makes complex with organic compounds. This stress leads to the formation of a network of cracks and if the cracks reach a critical point the aggregate will fail. Andesite aggregates from twelve different occurrences in Hokkaido have been investigated, particular attention having been give to the deterioration on making montmorillonite-urea complex. Tests to distinguish such materials from normal aggregate are also discussed.
In accordance with the increase of the demmands for small diameter waterways, TBM has been watched with keenest interest recently. However, the standard for the objective judgement on the TBM feasibility has not been established as yet. The rate of penetration of TBM plays an important role as to her feasibility as the machine-operating rate as well. The authors carried out multivariate analysis to predict the rate of penetration by adopting those data, both mechanical and geological, obtained in-situ through driving an area of competent rock mass. Through this analysis, it has become clear that the rate of penetration is very sensitive to the mechanical factors including the effectiveness of much scraping, and that there is a distinctive change in the rate of penetration between the rock mass class CH and B-CH.