アースドリル工法におけるN値判定法

概要

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Piles for uses in construction are fundamental parts of buildings, and are required to be highly reliable in Japan where seismic activities are quite frequent. Under the Earth Drill Method, a pile construction method, the ground is drilled till its hardness indicator, N-value, reaches 50 before the piles are embedded, in order to secure the safety of the buildings. however, at construction sites where the geological layers are structured intricately, the ground hardness data obtained from standard penetration tests and the actual hardness of the drilling spots occasionally can be quite different; and the drilling process halts while the actual N-value is still less than 50. Enabling the operator of an earth boring machine to confirm a 50-plus N-value during a ground drilling process improves the reliability of the piles, which is advantageous not only for the contractors but for the expected residents in terms of safety and security. In this paper, a system is proposed to determine the 50-plus N-value of the ground during an earth drilling process. The system, operated under a support vector machine, revolves the bucket in the Earth Drill Method. This system, as a result, has made it possible to determine the 50-plus N-value with the judgment ratio of 91.3% for the polynominal kernel, 73.9% for the Gaussian kernel, and 82.6% for the sigmoid kernel.
公益社団法人計測自動制御学会の論文