Layerwise Summation Method For Ground Foundation Settlement Based On Duncan-chang Constitutive Model

Ground foundation settlement analysis is one of the important research contentof soil mechanics.In the existing settlement analyses,the most widely used is theclassical layer-wise summation method of consolidation test e-p curve or e-logpcurve based on complete confinement.To a certain extent,this method considered theeffect of the soil modulus of compressibility changed with base load,but it causedthe settlement calculation results far greater than the measured and it’s difficult tomeet the requirements of precision engineering calculation,because the calculationparameters are obtained by the disturbed soil sample through the consolidation testand the completely confined condition and the soil’s actual stress state hadsignificant difference.In addition,when conducting the ground foundation settlementanalysis by using this method,we must by checking the e-p curve or e-logp curve toget void ratio.Therefore,first it can cause human error.Second,owing to the e-p curveor e-logp curve is obtained through consolidation test of disturbed soil,it reflectneither the differences between undisturbed soil and disturbed soil,nor the effect offoundation soil modulus due to different causes stress in different depth.Consequently,on the basis of the mechanical mechanism of deformation of thefoundation settlement,we put forward a new layer-wise summation method of groundfoundation settlement analysis based on Duncan-Chang constitutive model.Themajor results and theories are as follows:Firstly,we consider the influence of foundation soil deformation modulusproduced by the depth or initial stress that the consolidation stress deformationmodulus of foundation soil.Then，we divided it into two part:the initial stress of thebulk stress and partial stress.We introduce the step-loading thought,and establish amethod to determine the different depth soil deformation modulus.Secondly,we divided the settlement of foundation into two parts, respectivelyare the additional volume stress and additional stress caused by settlement,andestablished the analysis model of foundation settlement.Then,we consider thenonlinear characteristics of foundation deformation, introduce incremental analysismethod,Hooke’s law and the Duncan-Chang model,and create an analysis method offoundation layer compression deformation.And,we use the principle of thelayer-wise summation method of ground foundation settlement analysis to set up anew method based on Duncan-Chang constitutive model.This method can not only reflect the effects of the influence of foundation soil deformation modulus caused byinitial stress and additional stress,but also can avoid the use of foundation soilcompression test curve and the static load test curve.Lastly,we through calculating and analyzing of engineering examples,andcomparing with the theory and measured values of the settlement analysis,whichshows that the method can meet the requirements of engineering calculationprecision，and has a certain rationality and feasibility.