Preliminary Study On Regional Method Of National Standard Of Liquefaction Discrimination Formula

Many earthquakes at home and abroad come with the phenomenon of liquefaction in recent years,and liquefaction damages has become the main secondary disaster caused by earthquake,so it has important engineering significance to study the liquefaction method,which has been paid attention increasingly by engineering circles.According to the N63.5 of earthquake site,Chinese scholars made the experience formula of liquefaction.It's adopted and has been widely used in the engineering.However,it is uncertain that the liquefaction judgment formula,which is from some parts of the country,is applicable to other regions in China.In February 24,2003,an earthquake with a magnitude of Ms 6.8 struck the Bachu-Jiashi area in the Xinjiang Uygur Autonomous Region of China,and the earthquake occurred the phenomenon of sand liquefaction in large area.This provides an opportunity to test the accuracy of the current seismic code in our country.The paper collects site data in bachu and typical earthquake of China,and analyses the characteristics of Bachu earthquake liquefaction.At the same time,the standard penetration value of liquefied sand regions were compared.This paper argues that the liquefaction distinguishing method relying on the standard penetration test must consider the characteristics of sandy soil in different regions,so it is necessary to carry out regional correction.Finally,the paper presents a method to reflect the regional characteristics of Bachu,and the reliability of the method is discussed.The main contents and achievements of this paper include:1.The paper adds up and compares liquefied site data of Bachu earthquake,Tangshan earthquake,Haicheng earthquake and Tonghai earthquake,which shows that the characteristics of sand liquefaction of Bachu earthquake are obvious.2.Based on the existing Code for Seismic Design of Building(GB50011-2010),we use the method of liquefaction judgment to determine the data of Bachu seismic data in this paper.The results show that the seismic code formula can be used in 9 degree liquefaction area,but there is a serious mistake of justice in the 8 and 7 degree liquefaction area,and the current seismic code liquefaction discrimination formula is not applicable in Bachu area.In summary,the current seismic code liquefaction formula does not apply in Bachu area.3.The relationship between shear wave velocity and relative density of soilsamples in Bachu and Tangshan area was compared,then this paper makes a preliminary analysis of the differences between the two regions.Our findings indicate that when relative density of liquefied soil in the two regions is same,their wave velocities are very close.Therefore,the shear wave velocity can be used to represent the relative density of sand in Tangshan and Bachu.4.This paper compares N ~ Vscurves in different regions,which is found that There are significant differences between Bachu and other areas.Accordingly,it is reasonable that Vs ~ N63.5curves are regarded as the parameter representing the difference of the soil anti-liquefying ability in different areas.5.Thought basis of the relationship of Vs and N63.5 in Bachu and Tangshan,this article has preliminary discussion on regional correction of liquefaction discrimination formula...