粉土和砂土液化判别的现行规范对比

Comparison of the current codes for liquefaction evaluation of silty soil and sandy soil

粉土和砂土液化是地震和工程震动引起的显著的地质灾害之一,且往往危害巨大。本文首先介绍了液化现象的发生机理及相关抗震规范的变化历史,依据《建筑抗震设计规范》(GB50011-2010)、《公路工程抗震规范》(JTG B02-2013)与《铁路工程抗震设计规范》(GB 50111-2006)(2009版)中关于粉土和砂土液化的判别步骤,对其进行分析总结,指出三种规范中对液化判别的区别与联系。继而通过具体工程实例进行了液化计算的对比分析与标准贯入锤击数临界值公式的研究探讨,指出公路规范的液化判别经验公式与实际情况相差较大,铁路规范无法定量估计粉土和砂土液化的危害程度以及这三个规范均存在低估砂土中黏粒含量作用等问题。最后针对上述问题提出了合理性建议,旨在使工程实际中粉土和砂土的液化判别计算更具科学合理性。

The liquefaction of silty soil and sandy soil is one of the significant geological hazards caused by earthquake and engineering vibration,which often result in great damage. Based on engineering examples,the mechanism of the liquefaction of silty soil and sandy soil is firstly presented as well as the history changes of relating to the seismic codes. Three different design codes,such as Code of Seismic Design of Buildings（ GB 50011-2010）,Specifation of Seismic Design for Highway Engineering（ JTG B02-2013）and Code for Seismic Design of Railway Engineering（ GB 50111-2006）（ 2009 Edition） are used to summarize the recognition steps for the liquefaction of silty soil and sandy soil. The differences and connections among the liquefaction criteria in these codes are pointed out. Combined the comparative analysis of the liquefaction calculation and discussion of the SPT threshold formula,some conclusions are pointed out in this paper. The difference between the empirical formula of the liquefaction of the highway code and the actual situation is larger,and the hazard degree of the liquefaction of silty soil and sandy soil cannot be quantitatively estimated by the railway code. The effect of clay content in sand is underestimated in these three codes. In view of all above,this paper finally puts forward some reasonable suggestions,which could make the calculation of the liquefaction of silty soil and sandy soil in engineering practice more scientific and reasonable.