Discrimination And Prediction Analysis Of Sand Liquefaction In A Highway Site

Since 1964,there was a magnitude 8.5 earthquake in Alaska,the United States,and a magnitude 7.5 earthquake in Niigata County,Japan.Large-scale earthquake liquefaction caused disasters such as house subsidence,bridge and dam collapse,road damage,farmland self overflow,large-scale soil flow collapse,etc.,which caused widespread concern and Research on Earthquake liquefaction by scholars from all over the world.Therefore,it is very important for the selection of construction site and the selection of liquefaction protection measures to determine the liquefaction situation of site sand reasonably and accurately.In recent years,the deformation and flow failure of soil caused by earthquake liquefaction is still one of the main forms of earthquake disaster.So it is of great significance to study the deformation after liquefaction and predict the deformation after liquefaction for the subsequent engineering design and construction.In this paper,the highway site is taken as the research object.According to?Code for Highway Engineering Geological Investigation??JTG C20-2011?and?Specification of Seismic Design for Highway Engineering??JTG B02-2013?,the seismic liquefaction discrimination method is used to distinguish the possibility of seismic liquefaction of the site.The FLAC^3D numerical simulation software is used to evaluate the liquefaction of the site,and the results are compared with those of the standard method.Combined with the previous research results and FLAC^3D numerical simulation software,the deformation of the study area after earthquake liquefaction under certain conditions is estimated.The research results are as follows:?1?Within the study area,,according to the underground water level 2 meters below the natural surface and the seismic fortification intensity of 8 degrees,use?Code for Highway Engineering Geological Investigation??JTG C20-2011?to distinguish:the stratum in the study area is not liquefied;use?Specification of Seismic Design for Highway Engineering??JTG B02-2013?judgment:the third layer of fine sand has the possibility of liquefaction,and the liquefaction grade is slight liquefaction.?2?According to the results of FLAC^3D numerical simulation,under the action of vibration load,through observing the changes of pore water pressure,effective stress and excess pore pressure ratio of the monitoring node with time,the third layer of fine sand is likely to liquefy,and the simulation results are basically consistent with the judgment results of code for seismic resistance of Highway Engineering?JTG b02-2013?.?3?Under the condition of judging the liquefaction of soil layer,according to the prediction and estimation of the vertical deformation mechanism of earthquake liquefaction,the maximum settlement of 7.20cm is not much different from that predicted by FLAC^3D on the same order of magnitude;according to the prediction and estimation of the lateral displacement of the surface based on the mechanism of lateral deformation,the maximum displacement of about 15.0cm is basically the same as that predicted by FLAC^3D of 15.97cm,It shows that FLAC^3D has high accuracy in the discrimination of earthquake liquefaction and deformation prediction analysis.