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

在2007年的新竹中越树地震中，由于回填土液化，农村污水管道遭到严重破坏。而在2004年新竹县地震中因液化而损坏的污水管道，由于回填土中没有液化，采用石灰外加剂稳定的砂质土进行了回填修复。本文通过对2007年新竹县中越树地震对农村污水管道的破坏进行了研究，并与2004年地震对农村污水管道的破坏进行了对比，证明了石灰掺合料稳定的回填土具有有效的抗液化能力。然后，为了定量评价石灰外加剂稳定砂质土的抗液化性能，进行了一系列无侧限压缩试验。直径5cm，高10cm的土样在潮湿容器中压实并固化56天。结果表明，稳定土的无侧限抗压强度随龄期的延长而增大，当石灰掺量为干质量的5%时，稳定土的无侧限抗压强度可达到充填土所需的100 ~ 200 kPa。指出了稳定土开挖中可能遇到的一些困难。压实前的非压实期和石灰稳定土浸水对稳定土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.