中文摘要：

针对3种不同粒径的碎石集料进行垂直压力分别为50 kPa、100 kPa、150 kPa以及200 kPa的室内大型直剪试验，分析直剪条件下碎石材料的力学性能，同时利用离散元软件PFC3D建立碎石材料直剪试验的颗粒流模型；通过对比室内试验结果，对模型的细观参数进行标定。在此基础上，分析直剪过程中碎石之间的作用力及位移的演变。结果表明：随着垂直压力的增加，碎石集料的抗剪强度也在不断增加，其抗剪强度包络线可表述为幂函数型式；所选取各级垂直压力作用下，垂直压力越小，剪胀越明显；在选定的碎石粒径范围内，相同垂直压力下的集料抗剪强度以及压缩量随着粒径的增加而增加，而表征摩擦角则减小；直剪过程中碎石材料的体应变体现出不均匀性。

英文摘要：

To study the mechanical behavior of crushed stone aggregate under direct shear conditions , indoor large-scale direct shear tests were conducted with crushed stone aggregate of three different grain diameters un-der the respective normal stresses of 50 kPa、100 kPa、150 kPa and 200 kPa .On this basis ,The particle flow model was constructed by PFC3D （Particle Flow Code 3D） . Through comparing with the indoor tests results , the meso-parameters of the PFC3D model were calibrated and the changing applied forces and displacements of crushed stones in the direct shear process were studied . The research results show as follows ：The shearing strength of the crushed stone aggregate increases continuously along with rising of the normal stresses and its enveloping curve may be expressed in the shape of the power function ;under the action of the various levels of chosen normal stresses , the smaller the normal stress , the larger the shear dilation ;within the range of the chosen grain diameters , under the action of the same normal stress , the shearing strength and the compression displacement grow with increasing of grain diameters while the apparent friction angle shows an opposite chan-ging trend ;volumetric strains of crushed stones demonstrate nonuniformity during direct shearing .