颗粒级配对粗粒土强度与变形特性影响的研究

STUDY OF STRENGTH AND DEFORMATION CHARACTERISTIC OF UNBOUND GRANUAL MATERIAL WITH DIFFERENT GRAIN COMPOSITION

采用三维颗粒流软件PFC3D的内置FISH语言,进行二次开发,模拟粗粒土级配,建立一个研究高铁填方路基粗粒土变形特性的颗粒流模型。通过粗粒土三轴试验,标定了表征粗粒土细观力学性质的模型参数,并验证了模型的有效性。考虑粗粒土曲率系数和不均匀系数对颗粒级配的影响,模拟并研究了5种不同级配下粗粒土在3种不同围压下的变形特性。试验结果表明,曲率系数对粗颗粒土变形特性影响较大,当其有效粒径与中值粒径及限制粒径的差距过大时,粗粒土中颗粒填充及致密性将变差,变形增大,强度降低。以较大曲率系数与较大不均匀系数组合的粗粒土受力性能较好,但此种级配的粗粒土压缩性大。级配良好且不均匀系数较大,其应力链分布越均匀,颗粒的挤压效果越显著,力的传递和分配也越均匀。

To study the strength and deformation characteristic of unbound granular materials of high-speed railway,a granular flow model is established with the internal FISH language of three-dimensional particle flow code PFC3 D. Meanwhile,the micro parameters of unbound granular materials are calibrated with the conventional triaxial test results. Considering the influence of the curvature coefficient and the uniformity coefficient on the grain size distribution,five kinds of different grain composition of unbound granular materials are simulated under three different confining pressures. The results show that： There is a predominant factor in the curvature coefficient of unbound granular materials. The differences between the effective size,median diameter and constrained size can＇t be allowed too large,because the strength behaviors of the unbound granular materials with large curvaturecoefficient and uneven coefficient performances are higher than the others,and the deformation behaviors become more and more large. The non- uniformity coefficient is another important factor on the strength and deformation behavior of unbound granular materials. With the larger non- uniformity coefficient and well-graded granular materials won＇t changing the force chain distribution under the different stress condition,and the extrusion becomes more obvious and the transfer and distribution of force are more uniform.