Abstract：Research purposes: Expansive soil has the characteristics of intensive dilation shrinkage and is often in a non － satruated situation． Its strength and volume change with the change of water content，resulting in destruction of buildings． For construction of the expansive soil subgrade of Yuxi － Mengzi Railway，by using particle flow discrete element method，the numerical simulation of wet and dry sizing effect in expansive soils was made with the beginning of changing particle intensity and swelling － shrinking particle size，and the analysis of its failure characteristics and process was made．
Research conclusions: The particle flow discrete element method can reasonably reproduce interior expansive soli and free expansion rate tests with the equilibrium swelling pressure method． From doing the single simulation test and multiple simulation tests to the expansive soil subgrade，the superficial zone slump phenomenon of the expensive soil subgrade under swelling － shrinkage cycle is revealed in the microscopic point of view． Contrasting the failure characteristics of the filled embankment shows the situation of numerical simulation almost tallies with the site situation．
Yang Heping，Zhao Pengcheng，Zheng Jianlong．Classification of Expansive Soils Used as Embankment Fills［J］． Chinese Journal of Geotechnical Engineering，2009( 2) : 194 － 196．
［2］ 陈孚华． 膨胀土上的基础［M］． 北京: 中国建筑工业出版社，1979．
Chen Fuhua． Foundation on Expansive Soils［M］．Beijing: China Architecture ＆ Building Press，1979．
Han Huizeng，Wen Jiangquan，Li Shufen． Researeh on the Swelling and Shrinkage of the Swelling Rock along the Nankun Railway［J］． Journal of Southwest Jiaotong University，1995( 3) : 239 － 242．
Jiang Zhongxin，Qin Xiaolin，Wen Jiangquan，etc．Geological Characteristic of Expansive Laterite at Natong Test Cutting of Guangxi Province［J］． Journal of Railway Engineer Society，1998( 3) : 86 － 96．
［7］ C． Wang，D． D． Tannant，P． A． Lilly． Numerical analysis of the stability of heavily jointed rock slopes using PFC2D． ［J］． International Journal of Rock Mechanics ＆ Mining Sciences，2003( 40) : 415 － 424．
［8］ Nick Thompson，Matthew R． Bennett，Nick Petford Development of Characteristic Volcanic Debris Avalanche Deposit Structures: New Insight from Distinct Element Simulations［J］． Journal of Volcanology and Geothermal Research，2010( 192) : 191 － 200．
［9］ Calvetti，F． ，Crosta，G． and Tatarella，M． Numerical Simulation of Dry Granular Flows: from There Production of Small Scale Experiments to the Prediction of Rock Avalanches Rivista Ltaianal ［J］． Di Geotecnica，2000( 2) : 21 － 38．
2011, Vol. 28 
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