報告書番号

382056

タイトル（和文）

地上式ＬＮＧタンク基礎の耐震性（その１）－地盤調査および杭基礎構造物の振動特性－

タイトル（英文）

ASEISMIC CHARACTERISTICS OF LNG STORAGE TANKWITH PILE FOUNDATION (1) -INVESTIGATION OF GROUND PROPERTIES IN-SITU AND DYNAMIC BEHAVOIR OF PILE FOUNDATION-

概要 （図表や脚注は「報告書全文」に掲載しております）

日本海ＬＮＧ（株）新潟基地は計６基，総貯蔵量５２万ｋｌのタンク施設を中心として周辺に各種関連設備を有するもので，タンクは重要かつ巨大な構造物であるため，長期的安定性および地震安定性について設計・施工の両面について詳細な検討が行なわれた。しかしながら，タンク施設の重要性を考え，実際に地盤および構造物の性状を計測し，耐震性を確認した。実施した内容は，地盤調査（ボーリング孔壁加圧試験，弾性波探査），起振実験（試験杭基礎，実物タンク床版）等で，計測結果を解析し，地盤反力係数，減衰定数などの地盤物性および杭基礎構造物の振動特性（共振々動数，減衰性）を検討し，設計の有効性について検証した。

概要 （英文）

TO EVALUATE THE DYNAMIC STABILITY OF THE LNGSTORAGE TANKS DURING THE EARTHQUAKE SHAKING, THE SEVERAL INVESTIGATIONS ARE CARRIED OUT IN NIIGATA STATION OF NIHONKAI LNG CO. THESE TANKS ARE ESTABLISHED ON THE RC SLAB OF 64M IN DIAMETER AND 1M IN THICKNESS WITH PILE FOUNDATION, AND ARE COMPOSED OF TWO 100,000 KL AND FOUR 80,000 KL TANKS. FROM THE INVESTIGATION OF GROUND STRUCTURE, THE VIBRATION TESTBY VIBRATIONAL MACHINE AND OBSERVATION OF MICROTREMORS, THE RESULTS ARE OBTAINED AS TO THE DYNAMIC PROPERTIES OF SOIL AND DYNAMIC CHARACTERISTICS OF THE TANK FOUNDATION WITH PILES. THE DYNAMIC PROPERTIES OF SOIL INDICATES LARGE VALUES BY THE GROUND IMPROVEMENT, AND THE GROUND STRUCTURE OBTAINED FROM THE ELASTIC WAVE PROSPECTION IS WELL ABLE TO INTERPRET THE RESULTS OF VIBRATIONAL TEST OF GROUND. THE RESONANT FREQUENCY OF TANK FOUNDATION DECREASES WITH THE INCREASING VIBRATIONAL FORCE, WHICH INDICATES THE NON-LINEAR CHARACTERISTICS OF THE TANK FOUNDATION AND SURROUND SOIL SYSTEM. THOUGH THE DAMPING FACTOR OF PILE FOUNDATION IS 3.5 TO 4.9 PERCENT OF CRITICAL DAMPING FOR THE SINGLE PILE, IT BECOMES LARGE VALUE (19 TO 22 PERCENT OF CRITICAL DAMPING) ON THE CASE OF SEVEN PILES DUE TO THE INTERACTION BETWEEN THE PILES AND GROUND. THE BENDING MOMENT AND SHEARING FORCE ESTIMATED FROM CHANG S FORMULA WELL COINCIDE WITH THE OBSERVATIONAL VALUES.

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