基于颗粒流的膨胀土路基破坏特征分析

Analysis of Failure Properties of Expansive Soil Subgrade with Particle Flow Simulation

研究目的:膨胀土具有强烈胀缩性,常处于非饱和状态,对水分状态的变化十分敏感,并由此引起膨胀土强度和体积的变化,往往造成工程建筑物的破坏。结合新建玉蒙线膨胀土路基的修筑,利用颗粒流离散元方法,对膨胀土的干湿胀缩效应从颗粒间强度变化及颗粒体积胀缩入手进行数值模拟,分析膨胀土路基在干湿胀缩循环下的破坏特征及过程。研究结论:颗粒流数值方法可以合理再现膨胀土的室内加压平衡法膨胀力测试实验及自由膨胀率测试实验;通过对膨胀土路基进行单次胀缩及多次胀缩模拟试验,可从细观角度揭示了膨胀土路基在胀缩循环下的浅表层塌滑现象;对比现场部分填筑中路基的破坏特征,表明数值模拟与现场情况基本吻合。

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.