報告書番号

380051

タイトル（和文）

セメント系地盤改良の耐震効果に関する研究－室内土質試験結果からみた改良効果－

タイトル（英文）

ASEISMIC EFFECT OF CEMENT-MIXED SOIL IMPROVEMENT -THE EFFECTS THROUGH THE RESULT OF LABORATORY TESTS-

概要 （図表や脚注は「報告書全文」に掲載しております）

地盤改良による耐震効果を調べるため，粘性土が主体の超軟弱地盤をセメント系深層混合攪拌工法により地盤改良を施して諸試験を実施した。本報告は，前報の原位置調査・試験に続いて地盤材料の静的・動的力学特性を不攪乱試料を用いた室内試験によって求め，改良効果について検討した。その結果（１）セメント深層混合処理によって作成されたソイルセメント杭は在来地盤粘性土に比べて静的強度変形特性，動的強度変形特性すべてについて著しい改良効果を示した。（２）現場から採取した粘土を使用して室内で作成したソイルセメントは，原位置改良土に比べて大きい強度を示した。これは原位置改良土の不均一性と，採取時の攪乱に起因するものと考えられる。（３）改良土および未改良土のせん断剛性率および改良土の減衰定数は拘束応力依存性を示したが，未改良の粘性土の減衰定数は拘束応力依存性を示さなかった。

概要 （英文）

FOLLOWING THE PREVIOUS PAPER(ON RESULTS OF IN-SITU TESTS NO.380050),THIS PAPER DESCRIBES THE RESULTS OF THE DYNAMICAND STATIC PROPERTIES OF THE IMPROVED SOILS AND THE UNIMPROVED SOILS,WHICH WERE PERFORMED IN LABORATORY. AND THE COMPARISON AMONG THE RESULTSOF LABORATORY AND IN-SITU TESTS ARE SHOWN.THE RESULTS OF THIS RESEARCHARE SUMMARIZED AS FOLLOWS. (1)ON THE EFFECT OF THE MECHANICAL PROPERTIES OF THE SOIL IMPROVEMENT. (1)THE IMPROVED SOILS BY DEEP MIXING IMPROVEMENT WITH CEMENT IS MORE ADVANCED ON DYNAMIC AND STATIC MECHANICAL PROPERTIES THAN THOSE OF UNIMPROVED SOILS. (2)IT WAS SHOWN THAT THE SHEARSTRENGTH AND THE SHEAR MODULUS OF IMPROVED SOILS IN LABORATORY WERE HIGHER THAN THOSE OF IN-SITU IMPROVED SOILS,IN COMPARISON WITH THE SHEAR STRENGTH AND SHEAR MODULUS OF THE IMPROVED IN-SITU SOIL AND THOSE OF SOIL IMPROVED IN LABORATORY.FOR THE REASONS OF THOSE,THE FOLLOWINGS ARE POINTED OUT. 1)THE IMPROVED SOILS IN-SITU WERE MIXED UNEQUALLY FOR IMPROVED SOIL IN LABORATORY. 2)THE SAMPLES OF IMPROVED SOIL IN-SITU WERE DISTURBED AT SAMPLING. (2)MECHANICAL PROPERTIES OF UNIMPROVED SOIL. (1)THEDISTRIBUTION OF PRE-COMPRESSION LOAD IN DEPTH WERE OBTAINED BY ONE DIMENTIONAL CONSOLIDATION TESTS.FROM THESE TESTS,IT IS SHOWN THE SOILS WERE TOTALLY NORMALLY CONSOLIDATED STATES.HOWEVER,NEAR THE GROUND SURFACE,THEY WERE SLIGHTLY IN OVER CONSOLIDATED. (2)THE COEFFICIENT OF LATERAL EARTH PRESSURE AT REST(KO)BY TRIAXIAL TEST DIVICE WAS OBTAIND.THE KO VALUE OF NORMALLY CONSIDATED SOILS SAMPLED FROM G.L.0 M TO G.L-10M IN DEPTH WERE 0.3 0.4,AND KO=0.3 IN DEPTH G.L-17M.

報告者

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