国内外液化砂砾土土性对比分析

砂土液化问题的研究特别是砂土液化的判别目前已经取得了较大的进展,并在国内外现行的规范中充分反映,而砂砾土由于颗粒大、透水性好,普遍认为地震时孔压不至于上升至液化的程度,往往将其划分为非液化土类。通过调查汶川地震砂砾土液化情况以及勘察试验获取其土性资料,对比分析了国内外液化砂砾土的地质背景及土性特征。主要认识为：①以往国内外砂砾土液化实例虽然有限,但已经表明松散-稍密的砂砾土在一定的地震强度下仍有可能发生液化,而2008年汶川地震中的大量砂砾土液化的事实,说明笼统地将砂砾土划归为非液化土类的做法有误;②汶川地震液化砂砾土的颗粒级配范围涵盖了国内外其他地震的颗粒级配,研究汶川地震的砂砾土液化问题具有代表性和普遍性,以此建立的砂砾土液化评价方法在国际上应具有通用性。

Comparison and Analysis of the Performance of Liquescent Gravel Soil at Home and Abroad

The study of sand liquefaction issues,especially in sand liquefaction evaluation,has made significant progress,and its fruits are widely used in the real engineering project or adopted in the seismic code,while the liquefaction potential of gravels is still unclear.The gravels were usually regarded as non-liquefiable soils because of large grain sizes and generally high permeabilities in the past.Field investigation and test of gravels liquefaction sites following the 2008 Wenchuan earthquake,and comparison of gravels liquefied cases history from previous earthquakes,reveal that：（1） Limited gravels liquefaction cases history from previous earthquakes warn that loose to moderate density of gravels have much potential to liquefy under a given earthquake shaking.The widespread gravels liquefaction following the 2008 Wenchuan earthquake reveal it is not reasonable to regard gravels as non-liquefiable soils without any treatment;（2） The grain size distribution curves from the Wenchuan earthquake cover a wider range of grain sizes than those reported from previous earthquakes,indicating that gravels characteristics liquefied in the Wenchuan earthquake are representative and universal.The gravels liquefaction evaluation method developed from the Wenchuan earthquake should be feasible for worldwide use.