德阳松柏村典型液化震害剖析

2008 年 5 月 12 日中国发生的 8.0 级汶川大地震中， 位于 Ⅶ 、 Ⅷ 度交接处的德阳松柏村液化破坏十分明显， 喷砂类型丰富，液化伴随大量地裂缝，液化加震现象十分显著 ， 具有典型研究价值。对该村进行了详细的现场测试并 与以往液化震害进行了对比分析，结果表明： 尽管松柏村地表主要喷出物是中砂和粗砂，但实际液化土与喷出物差别显著，主要为砂砾土液化；以往还没有提出过适于工程应用的砂砾土液化判别方法，而超重型动力触探（ DPT ）具有设备简单、经济实用、测试数据连续的优点，可作为砂砾土液化预测的核心指标； 松柏村大量地裂缝现象不是由次断层造成而是由土层液化引起，而液化产生地裂缝的基本条件为地表较平坦（ <3% ）以及液化土层水平分布不均匀； 液化减震的基本条件为上覆非液化层足够厚且较为密实，但定量评价方法还有待进一步研究。

Typical case study of liquefaction-induced damage at Songbai village following Wenchuan Earthquake

The serious damage in Songbai village,Deyang,located at the boundary of seismic intensity zone Ⅶ and Ⅷ,is induced significantly by liquefaction following the 2008 Wenchuan Earthquake.The large amount of spouted soils categories,a lot of liquefaction-generated ground fissures and the apparent liquefaction-aggravated damage are the typical features and are worth for further study.The detailed in-situ tests and comparison with the previous liquefaction-induced damage reveal:(1) The actual liquefied soils are gravels and significantly different from the spouted deposits,while most of which are medium and coarse sand.(2) An efficacious filed test method for measuring gravel liquefaction resistance has not been proposed ever before.The Chinese dynamic penetration test(DPT) is strongly recommended for gravel liquefaction evaluation for its simple apparatus,economical test,continuous data acquisition,etc.(3) The abundant ground fissures in Songbai village are generated by gravel liquefaction rather than the raptures or secondary faults.The fundamental conditions for the generation of ground fissures by liquefaction are the flat ground surface(slop less than 3%) and horizontal non-uniform distribution of liquefiable soils.(4) The fundamental conditions for seismic damage mitigation by liquefaction are the thick upper non-liquefiable soils and relativey dense upper non-liquefiable soil cap.The corresponding quantitative assessment method needs to be further studied.