Toward a safe and secure geo-environment reinforced by soil stabilization using lime admixture.

在2007年的新潟县中越大地震中，由于回填土液化，农村污水管道遭到严重破坏。但在2004年新潟县切津地震中因液化而受损的大部分排水管道，经石灰稳定桑迪土回填修复后，由于回填土未发生液化，未受影响。通过对2007年日本新潟县地震中越冲县农村排水管道的破坏情况进行调查，并与2004年的结果进行对比，说明石灰稳定回填土具有良好的抗液化性能。为了定量评价石灰加固桑迪的抗液化性能，进行了一系列的无侧限压缩试验。将直径5cm、高10 cm的土样在潮湿的容器中压实并养护56天。结果表明，固化土的无侧限抗压强度随养护时间的延长而增加，当石灰掺量为干质量的5%时，可达到回填土所要求的无侧限抗压强度100 ~ 200 kPa。指出了稳定土开挖中可能遇到的一些困难。压实前的不压实期以及石灰稳定土的浸水时间对稳定土的无侧限抗压强度随时间的增加有影响。

Rural sewerage pipelines were severely damaged by liquefaction of backfill soil during the Niigataken Chuetsu-oki Earthquake in 2007. But a large length of the sewerage pipelines which had been damaged by the liquefaction during the Niigataken Chetsu Earthequake in 2004 and been repaired by backfilling the sandy soil stabilized by lime admixture remained unhurt because of no liquefaction in the backfill. In the paper the damages of the rural sewerage pipelines caused by the Niigataken Chuetsu-oki Earthquake in 2007 are investigated and compared with those in 2004 to show an effective liquefaction resistance of the backfill soil stabilized by the lime admixture. Then, in order to evaluate quantitatively the liquefaction resistance of the sandy soil stabilized by the lime admixture, a series of unconfined compression test is carried out. Soil specimen 5cm in diameter and 10cm in height are compacted and cured in a humid container during 56 days. It is shown that the unconfined compression strength of the stabilized soil increases with curing period and, in the case of addition of 5% quantity in dry mass of lime admixture, reaches successfully 100 to 200 kPa which is the unconfined compression strength required for the backfill soil. Some difficult may which be encountered in excavating the stabilized soil is pointed out. It is also shown that a non-compaction period before compaction as well as an immersion of lime-stabilized soil into water affects the increase of unconfined compression strength of the stabilized soil with time.