A Study of the Effect of Permeability Difference of Depositional Architecture on Sand Liquefaction
Current methods for identifying sand liquefaction,both in domestic and international contexts,are primarily based on in-situ testing data from easily liquefiable soils,without adequately considering the permeability differences between adjacent soil layers.However,under seismic loads,these permeability differences can significantly influence the accumulation of excess pore water pressure in liquefied soils.A study based on static cone penetration and drilling data from liquefaction sites in New Zealand established a detailed profile of sand liquefaction during earthquakes.The analysis revealed that the distribution of surface liquefaction was closely linked to the structural characteristics of the site's soil layers.Further investigation through physical model experiments and numerical simulations demonstrated that high-permeability gravel layers have a pronounced effect on reducing the accumulation of excess pore water pressure in neighboring liquefiable soils.This influence can be quantitatively characterized by the vertical equivalent permeability coefficient of the soil layer.As the equivalent permeability coefficient increases,the accumulation of excess pore water pressure in liquefiable soils significantly decreases,thereby reducing the potential for liquefaction.Therefore,to enhance the accuracy of liquefaction assessments,it is crucial to account for permeability differences between adjacent soil layers in the sand liquefaction criteria.This would lead to more reliable predictions,especially in areas where soil permeability varies.
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