Test Research On The Liquefaction Properties Of Silty Soil

The saturated silt,widely distributed in a variety of alluvial plains,fluvial delta,coastal plains and lacustrine plains region is one of the soil type which is frequently encountered in the construction.This type of soil contains free water mostly,likely to be liquefied in the earthquake and has weak bearing capacity.Beijing-Shanghai high-speed railway is mainly to go through the Haihe River,Yellow River washing deposition area,the Yangtza platform area and other river washing deposition regions,but also in the VII degrees,VIII degrees and IX degrees seismic zones,so under the earthquake action the saturated silt in these areas is likely to be liquefied.The object of study in this work is the silty soil which compose the foundation of Beijing to Shanghai high-speed railway,mainly though the indoordynamic test to analyze the liquefaction features of the silt in the dynamic loads,with the view to provide more reliable information for practical engineering and some reference for related research work about the liquefaction of soil.The main contents are as follows:1,Existing seismic liquefaction-related research results and research methods both at home and abroad are collected. A summary is made about the mechanism of soil liquefaction and influencing factors,being familiar with the definition and classification of silt,physical and mechanical and other properties,and a short description is made about the existing silt liquefaction method.2,Though the general tri-axial test on the not reinforced and reinforced soil sample,an analysis is made about the stress-strain curve and the growth trend of shear strength of the sample under isotropic consolidation.It can be seen,density and consolidation pressure have important influence on the stress-strain curve and the shear strength of silt.In the course of the test,stress-strain curve is not onefold,but has a transformation because of the change of density and consolidation pressure.3,Based on the result of dynamic triaxial test of saturated silt,it can be seen that with the passage of time,the axial stress,axial strain and excess pore water pressure all have change regular pattern.Besides,the impact of dry density and consolidation pressure on the liquefaction resistance of saturate silt.The work studied the model of excess pore water pressure,from which it can be found that the not reinforce sample has a model according with the Seed model which is acquitted by sand under isotropic consolidating and non-drainage.Otherwise,the reinforced sample has a model according with the regular pattern of power function.The last is the research about the deformation properties of the silt.Generally,secant shear modulus and damping ratio are used to describe nonlinear and hysteretic nature of soil.So it is necessary to to discuss the impact of dry density of silt on this two parameters.