Comparative Study on Sandy Soil Liquefaction Judgment of Deep Overburden in Riverbed
Liquefaction of sandwill leadtoinstability of foundation and damage of overlyingbuilding structure,whichisone of the common engineer-ing geological disasters inseismic area.Therefore,the liquefactiondiscrimination of proposedsiteisanimportant issueinsurvey and design.This paper uses the particlesizemethod,standardpenetrationtest method,dynamic triaxial test method and shear wave velocitymethod todiscriminate the sandliquefactionof the Holocene lacustrine deposits inthe riverbedoverburdenof the lower reservoir area.The results showthat:discrepancies exist in the discrimination results of the upper lacustrine deposits among different methods.The particle size analysis reveals a clay content of up to 50%,and the failure strength derived from the dynamic triaxial test is over 10 kPa lower than the calculated liquefaction shear stress of the soil layer,which is judged to be non-liquefaction.However,the standard penetration blow count of the soil layer is smaller than the critical standard pene-tration blow count,and the shear wave velocity is also below the upper limit,so it is judged that there is a possibility of liquefaction.Regarding the silty fine sand layer in the lower part of the lacustrine deposits,all methods consistently indicate the presence of sand liquefaction issues.Based on the comprehensive comparison and analysis of the liquefaction discrimination results of four different methods,it is finally evaluated that the upper muddy clay layer of the lacustrine will not be liquefied,but the lower silty sand layer has weak liquefaction resistance and has sand liq-uefaction problems.The study results have significant practical value for the prevention and control of sand liquefaction in engineering area.
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