格宾网加筋土强度和变形特性的三维离散元细观模拟

Mesoscopic numerical simulation of strength and deformation properties of gabion-mesh reinforced soil by three-dimensional discrete element method

为揭示格宾网加筋土强度和变形特性的细观力学本质,利用PFC3D三维离散元计算平台的FISH语言编写数值伺服程序实现大三轴试验环境和土颗粒模型生成算法,模拟大三轴素土试样应力-应变宏观响应校正土颗粒细观参数;然后,引入平行黏结构造格宾网颗粒流模型,通过模拟其室内拉伸试验校正格宾网模型细观参数;在此基础上,建立格宾网加筋土大三轴试样的三维颗粒数值模型模拟格宾网加筋土应力-应变关系,揭示格宾网加筋土颗粒之间接触力和内部剪切位移场的渐进发展规律。研究结果表明:格宾网加筋土颗粒模型数值试验能对其力学机理做出定量和定性预测;在试样两端和两层格宾网之间,分别形成"八"字形和"><"形倾斜剪切带;随着试样围压增加,试样内部剪切带范围缩小;加筋层数较少时,剪切滑移带范围较大;土颗粒接触力在整个格宾网截面内分布较均匀,在两层格宾网之间集中到试样截面的中部。

In order to reveal the mesomechanical nature of strength and deformation properties of gabion-mesh reinforced soil, the numerical servo program for triaxial test environment and generation algorithm of soil particle model was developed using FISH language of PFC3 D platforms, and the mesoscopic parameters of soil particles were corrected through simulating the stress-strain macroscopic response of prime soil＇s large triaxial specimen. Then, the particle flow model of gabion-mesh was configured by installing parallel bond, and the mesoscopic parameters of gabion-mesh particle model were corrected by simulating its indoor tensile tests. On this basis, the three-dimensional particle numerical model of gabion-mesh reinforced soil＇s triaxial specimen was established to simulate the stress-strain relations of gabion-mesh reinforced soil. The progressive development law of the contact force between gabion-mesh reinforced soil particles and the internal shear displacement field was revealed. The results show that the gabion-mesh reinforced soil particles model numerical test can predict its quantitative and qualitative mechanical properties. The ＂∧＂-shape and ＂ 〉〈＂-shape tilt shearzones appear at both ends of the specimen and between two layers gabion-mesh, respectively. With the increase of the specimen＇s confining pressure, the internal shear zone is compressed. When the number of reinforcement layers decreases, the shear slip zone will be a wider range. The contact force between soil particles is evenly distributed in the entire gabion-mesh section; however, it is concentrated in the middle of the specimen＇s cross-section in between the two layers of gabion-mesh.