報告書番号

382046

タイトル（和文）

地中線シールドトンネル二次覆工コンクリートの熱特性，引張クリープおよび乾燥収縮

タイトル（英文）

THERMAL PROPERIES, TENSILE CREEP AND DRYING SHRINKAGE OF CONCRETES USED FOR LINING OF UNDERGROUND TRANSMISSION LINETUNNELS

概要 （図表や脚注は「報告書全文」に掲載しております）

地中線シールドトンネルの二次覆工コンクリートのひびわれ発生条件の検討を行なう目的で，普通，フライアッシュ，膨脹コンクリートの熱特性，引張クリープおよび乾燥収縮を測定し次の結果を得た。■コンクリートの線膨脹係数，熱伝導率，熱拡散率のセメントの種別による差は認められなかった。■膨脹コンクリートの断熱温度上昇は，材令１５日で約６０℃となり最高で，フライアッシュコンクートの温度上昇は約４１℃で最低であった。■引張クリープ試験は材令７日と２８日に載荷した。クリープひずみはフライアッシュコンクリートが最も大きく，普通コンクリート，膨脹コンクリートはほぼ同等の値を示した。セメントの種類による乾燥ひずみの差はほとんど認められなかった。ただし，ＣＡＳ＃２０の膨脹コンクリートは，湿潤養生３日後に約１１００×マイクロの膨脹ひずみを生じた。乾燥収縮係数は，１．４７～２．１９×１０マイクロ／ｇ／立方■となった。

概要 （英文）

FIVE MIXES OF CONCRETE WITH NORMAL PORT-LAND,FLY ASH,AND EXPANSIVE CEMENTS WERE SELECTED TO HAVE CHARACTERISTICS THAT PREVENT CRACKING IN THE LINING OF SHIELD SUNNELS FOR UNDERGROUND TRANSMISSION LINES.THEN,THERMAL PROPERTIES,TENSILE CREEP,AND DRYING SHRINKAGE OF THESE CONCRETES WERE MEASURED. THE COEFFICIENTS OF THERMAL EXPANSION WERE 9.9 10.9MICRO/DEGREE,REGARDLESS OF THE TYPE OF CEMENT USED.THE THERMAL CONDUCTIVITIED WERE 2.142 2.243KCAL PER KG PER DEGREE,AND THEDIFFERENCE ACCORDING TO THE TYPE OF MIX WAS NOT APPARENT.THE THERMAL DIFFUSIVITIES WERE 0.00300 0.00362SQUARE METER PER HOUR,ALSO REGARDLESS OF CEMENT TYPE.THE VALUES OF SPECIFIC HEAT WERE 0.264 0.304KCAL PER DEGREE. THE HIGHEST ADIABATIC TEMPERATURE RISE DUE TO HYDRATION OF CEMENT WAS ABOUT 60DEGREES UP TO THE AGE OF 15 DAYS IN EXPANSIVE CEMENT CONCRETE,AND THE LOWEST TEMPERATURE RISE WAS 41 DEGREES UP TO THE SAME AGE INFLY ASH CEMENT CONCRETE. IN THE TENSILE CREEP TEST SPECIMENS WERE LOADED AT THE AGES OF 7 AND 28 DAYS,AND KEPT UNDER LOAD FOR 97 DAYS.CREEP RECOVERIES WERE ALSO MEASURED. FLY ASH CONCRETE SHOWED THE LARGEST CREEPSTRAIN.AND,NORMAL PORTLAND CEMENT CONCRETE AND EXPANSIVE CEMENT CONCRETE SHOWED NEARLY EQUAL CREEP STRAINS. THE DRYING SHRINKAGE AFTER THE INITIATION OF DRYING WAS ABOUT 700MICRO IN THE NORMAL PORTLAND CEMENT CONCRETE WITH THE NORMAL STRENGTH OF 180KGF PER SQUARE CM,AND THE SHRINKAGE OF THE OTHER CONCRETES WAS ABOUT 500 580MICRO THE COEFFICIENTS OF DRYING SHRINKAGE ANALOGOUS TO THOSE OF THERMAL EXPANSION WERE CALCULATED ASSUMING WATER DIFFUSIVITIES AND WATER TRANSFER COEFFICIENTS,AND THE RESULTS WERE 1.47 2.19MICRO PER GRAMPER CUBIC CM.

報告者

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