Preliminary Study On Influencing Factors Of Gravelly Soils Liquefaction

Before the Wenchuan earthquake in 2008,there were few examples of gravelly soils liquefaction reported at home and abroad,which did not attract the attention in engineering and academic.It is usually considered that the permeability of gravelly soils is so better that the excess pore pressure produced in the earthquake is easily dissipate.Therefore,the gravelly soils is directly divided into the non-liquefied soil.However,in the Wenchuan earthquake,large-scale gravelly soils liquefaction occurred in the Chengdu plain,and it was a record that the world's largest gravelly soils liquefaction has been recorded,it had broken the traditional knowledge that natural gravelly soils have no liquefaction.At present,there is no uniform understanding of the influencing factors of gravelly soils liquefaction in the academic world,and even the same scholars have different conclusions at different times.The influence of burial conditions,soil parameters and other factors on liquefaction of gravelly soils is the basic work of studying on gravelly soils liquefaction.Based on the investigation data of Wenchuan earthquake,this paper studies the influence of burial conditions on the liquefaction of gravelly soils in Chengdu plain,and uses FLAC3 D software to simulate and analyze the liquefaction problem of gravelly soils.The main contents are as follows:1.The buried conditions of the gravelly soils in the Chengdu plain are deeply analyzed,including the groundwater level,the depth of the buried gravelly soils layer,the thickness of the overburden cohesive layer and the the drainage thickness.The mathematical model of the relationship between the shear wave velocity and the heavy dynamic penetration results is obtained.2.The constitutive model of FLAC3 D software and the suitable ground motion input are selected to reproduce the earthquake response of the four typical gravelly soils liquefaction and non-liquefaction sites in Wenchuan earthquake,and the result of simulating is coincident with the fact.The four sites are the Mianzhu City Wudu village,the Mianzhu City Xiangliu village,the Pixian County Shidimiao village and Dujiangyan City Ruikang garden.3.To establish the generalized model of the research on the rules of gravelly soils liquefaction,and the FLAC3 D is used to calculate the nearly 500 kinds of working conditions.The regularity of the input load intensity,soil parameters(the relative density,the permeability coefficient)and burial conditions(the overburden cohesive layer,the drainage layer thickness)influence on gravelly soils liquefaction was preliminarily studied.