| 講演要旨(和文) | | 大分県臼杵市および鹿児島県霧島市の特殊地下壕(防空壕)で,高周波CSMT装置によるニアフィールド領域での地下壕の電磁応答について調査した.送信点,測線等の多くの探査条件を変化させた結果,1.測線は地下壕に直交,2.水平ループアンテナは地下壕の延長方向に設置,3.送-受信点間距離は,インダクション数が過小にならない送受信間距離を測定前に把握しインダクション数が0.8程度以上とすることが地下壕検出に最も効果的であるとの結論を得た.この方法を用いて土被比(H/d)が6程度の地下壕では,壕の中心位置および抗壁位置をほぼ正確に把握することが可能となった.また実験および試錐の結果では,深度15m程度までの地下壕が1m程度の分解能で検出できた. |
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| | 講演要旨(英文) | | The surveys in Usuki and Kirishima have been conducted to measure the electromagnetic response of the air-raid shelters in various conditions, using the HFCSMT equipment. Analyzing these data, we conclude that the following method is the most effective to detect the position of shelters. First, the survey line is perpendicular to the strike of air-raid shelters, second, a horizontal loop-antenna is set up at the position along the extension of shelters, and third, the source-receiver distance should be about a skin depth in the Earth. Applying this method, the walls can be detected accurately for the shelters of which the ratios of the depth and the height are about six. The results of the test-borings support the conclusion that the shelters at the depth up to about 15m can be estimated in an accuracy of about one meter. |
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