Browsing by Author "Matikainen, Antti Johannes"

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    Excavation quality and statistical evaluation of laser scanned tunnel cross-sections
    (2013) Matikainen, Antti Johannes; Uotinen, Lauri; Halonen, Juha; Piirainen, Mikko; Yhdyskunta- ja ympäristötekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Rinne, Mikael
    The reason to undertake this subject was to find out, if the true excavation quality can be explained by statistical means derived from laser scanned tunnel cross-sections. The purpose of this thesis is to introduce indicator parameters for statistical evaluation of true excavation quality and apply them for quality assurance, economical inspection of excavated tunnel and risk analysis of costs. The true excavation quality has been determined in this thesis as follows: excavated mean cross-sectional area, continuance within excavation tolerances, excavated total volume, roughness of the excavated rock surface and mean circumference of the excavated cross-sections. These quality factors are explained by statistical indicator parameters, that have been derived from laser scanned tunnel cross-sections by random variables c and r. Random variable c illustrates the length of tunnel periphery. With mean and standard error of the sample mean, the mean length of circumference and shotcrete consumption can be determined. Random variable r illustrates excavation deviations, measured perpendicular between theoretical profile and realized excavation. With mean and standard error of the sample mean, the mean cross-sectional area can be determined and if multiplied with tunnel length the total volume. Standard deviation illustrates roughness of the realized tunnel periphery and quality. With confidence intervals the continuance within tolerances can be determined. Results presented in this work are obtained from Kalliorakennus-Yhtiöt Oy's Ring Railway (Kehärata) and Western Metro (Länsimetro) projects. The results suggest, that true excavation quality can be explained by statistical means. It is reasonable to point out that none of the distribution fittings could explain the data in all cases, therefore best fit was used. The total volume was calculated with statistical means and then result compared to modelled total volume (calculated with TMS Tunnelscan program) giving 0.1 % difference between the results. When studying quantity related costs, including: loading & hauling, post removal of under breaks and shotcreting with statistical means, the results suggested post-removal of under breaks as a determining cost factor. Methods presented in this work offer tools for calculating accurately the quantity of under breaks and even controlling them. Therefore, if under breaks can be controlled and their removal on the job can be done, calculations suggest to accepting the risk of under breaks. This means lowering the mean of random variable r, and same time increasing the risk of under breaks. In other words optimizing the excavation towards smaller over break as the profit gained from the loading & hauling cost changes was significant enough for controlling under breaks and making the best profit. According to calculations, by lowering the mean with 20 cm, and same time accepting the risk of under breaks, which increased from 0 to 0.6 % of the total excavation, the profit gained from the loading & hauling cost changes was 100 000 EUR / 1 km.