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含细粒砂性土相对于纯净砂在自然界中分布更为广泛,但是对于其液化判别,一直都是作为纯净砂液化判别的附属成果,没有得到足够的重视。回顾了中国规范方法与NCEER推荐方法,结合1999年台湾集集地震液化土与非液化土数据,发现两个方法定义纯净砂的矛盾,通过进一步对比判别结果,建议对两个方法做如下改进:1对中国规范方法,首先取消粉砂黏粒含量取3%的规定,并且对黏粒含量不大于3%且细粒含量大于15%的粉砂及粉土,取ρc=Fc/4,否则取3%;2对NCEER方法,当黏粒含量不大于3%时,只针对细粒含量大于20%的土,才考虑调整(N1)60。改进之后,中国规范方法过于保守的问题得到解决,NCEER方法对于黏粒含量不大于3%且细粒含量大于5%的土判别结果也不再偏于危险。
Compared with pure sand, fine sand sandy soil is more widely distributed in nature, but its liquefaction discrimination has always been an adjunct to liquefaction discrimination of pure sand, and has not been given enough attention. After reviewing the Chinese normative method and the NCEER recommendation method and combining with the data of liquefied soil and non-liquefiable soil of the 1999 Ji’ji Shizhui earthquake, we found the contradiction between the two methods to define the pure sand. By comparing the results of the two methods further, it is suggested to improve the two methods as follows: 1 For the Chinese standard method, first of all, the provisions of 3% of silt clay should be eliminated, and ρc = Fc / 4 for silt and silt with clay content of not more than 3% and fine content of more than 15% Take 3%; 2 For the NCEER method, when the clay content is not more than 3%, only consider the adjustment (N1) 60 for the soil with more than 20% of the fine grain content. After the improvement, the problem of excessively conservative Chinese norms was solved. The NCEER method was no longer dangerous for soil discrimination results with clay content not more than 3% and fine content more than 5%.