Study On The Application Of PFC Numerical Method In Large Area Loading Of Soft Foundation

In civil engineering large area loading is common factor which cause differential settlement.Whether to consider differential settlement depends on referenced standard which classify the foundation via modulus of compressibility and give out minimum settlement corresponding to classified foundation.Standard can only be used to make decision,whether or not to deal with loading foundation,can not make qualitative and quantitative analysis.Nowadays scholar deal with uneven settlement problem mainly via finite element numerical simulation,but for loose powder finite element method is not recommended.In order to overcome the shortcomings of existing research,particle flow code based on discrete element method is introduced,studying meso parameter during the progress of reaching ultimate load,and analyzing uneven settlement of double-layered soil via grey forecasting mode.The main contents of this paper are as follows:(1)Regarding the biaxial servo compression test as calibration test,the influence of micro parameters on macro parameters is studied and the results are summarized in form of table.(2)Built the relation between fric and friction angle,get fitted formula.The difficulties in choosing micro parameters is solved.(3)Study meso parameter during the progress of reaching ultimate load,draw out failure criterion fitting PFC: first get estimated carrying capacity by classical soil mechanics,then execute graded loading on PFC simulation,get real carrying capacity by load-settlement curve.(4)Put PFC into analysis of uneven settlement caused by large area loading in ZhanjiangGuangdong,in which gray prediction is introduced to study settlement.The result show that PFC fit such kind of problem not only because algorithm based on discrete element,but also the contour of PFC can show particle displacement and velocity real-time.The introduction of gray prediction can save more than half of simulated time.