石灰系固化材で安定処理された砂質土の耐液状化性能  [in Japanese] Liquefaction Resistance of Sandy Soil Stabilized by Lime Admixture  [in Japanese]

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Abstract

<p>2007年新潟県中越沖地震で,地盤の液状化による管路の被害が多数生じた.しかし,2004年新潟県中越地震で被災し復旧された埋戻し管路では,その大部分が,この2007年地震での被災をまぬがれた.埋戻しには,石灰系固化材を添加した安定処理土が用いられていた.まず,2007年地震で生じた管路の被災状況の調査にもとづき,石灰系固化材を用いた安定処理工法の液状化対策としての有効性を示した.次いで,安定処理土の耐液状化性能を探るため,養生期間56日にわたって土の一軸圧縮強さを測定した.乾燥質量比5%の添加で,所要の一軸圧縮強さを確保できることを確認した.しかし,養生時間とともに強度が増加し続けるため,再掘削が容易であるとする利点が損なわれる可能性が示唆された.固化材添加後の仮置きにより強度発現が緩慢になること,また水中浸漬により強度が大幅に低下することを示した.</p>

<p>While rural sewerage pipelines were severely damaged by liquefaction of backfill soil during the Niigataken Chuetsu-oki Earthquake in 2007, a large length of the sewerage pipelines, which had been damaged by the liquefaction during the Niigataken Chuetsu Earthquake in 2004 and been repaired by backfilling the sandy soil stabilized by lime admixture, escaped unharmed. In the paper the damages of the rural sewerage pipelines caused by the Niigataken Chuetsu-oki Earthquake in 2007 are investigated to show effectiveness of the liquefaction countermeasure using the backfill soil stabilized by the lime admixture. Then, in order to evaluate quantitatively the liquefaction resistance of the stabilized soil, a series of unconfined compression test is carried out. The test results show that, in the case of addition of 5% quantity in dry mass of lime admixture, the unconfined compression strength of the stabilized soil reaches more than the liquefaction resistance required for of the backfill soil. However, as this strength increases with curing time, some difficulty may be expected in re-excavating the stabilized soil in the future. To solve this, it is recommended that the lime-added soil should be left without compaction during some period before backfilling. It is also shown that the stabilized soil inconveniently decreases its unconfined compression strength after immersing into the water.</p>

Journal

  • Transactions of The Japanese Society of Irrigation, Drainage and Rural Engineering

    Transactions of The Japanese Society of Irrigation, Drainage and Rural Engineering 87(1), II_59-II_64, 2019

    The Japanese Society of Irrigation, Drainage and Rural Engineering

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