粗粒土是工程建设过程中经常遇到的一类土，由于室内仪器限制，通常将其按一定条件缩尺后进行室内大三轴试验，进而推算原级配土的强度特性。缩尺后替代级配与原级配存在着缩尺条件、尺寸效应等问题。在某高速公路大三轴试验数据基础上，运用 PFC2D 软件，将600×300 mm 样本经等质量替代法缩尺，比较了缩尺后不同尺寸样本的应力-应变曲线。结果表明：PFC2D可以很好的模拟三轴试验；缩尺后的样本应变模量降低，且随着样本尺寸的增大而增大，样本的抗剪强度也存在差异；等质量替代法对缩尺后样本的尺寸大小有限制；当样本颗粒级配相同时，不同尺寸样本在峰前阶段的尺寸效应不明显。%Coarse-grained soils are the soils that always are encountered in the process of engineer-ing construction.Due to indoor instrument limitations,Triaxial tests were performed under certain scale conditions and then the paper calculate the strength properties of original soil gradation.There are prob-lems of size effects and scale conditions between natural gradation and substitute gradation.According to the triaxial test data of some highway ,the sample of 600 ×300 mm will be scaled and the paper will com-pare stress-strain curves of samples of different sizes.The conclusions are as follows:PFC2D can simu-late triaxial tests accurately;Strain modulus decrease in the scale samples,and increase with the increas-ing of sample size;Shear strength of samples are different;the method of equal-weight replacement is limited to the size of the scaled samples;when the particles’size distribution is same ,different samples haven’t obvious size effects.In coarse-grained soil sample preparation process.
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