砂土侧限下土工合成材料拉伸试验离散元模拟

Discrete element simulation of tensile test of geosynthetics subjected to lateral confinement

为研究土工格栅拉伸性能,以室内无约束拉伸试验为基础,建立侧限约束下的格栅拉伸试验离散元PFC3D模型,分析拉伸速率、上覆荷载对其拉伸性能的敏感程度,探讨侧限约束下土体位移与格栅拉伸变形相互作用的机理,揭示筋土界面孔隙率的发展规律。结果表明:增大拉伸速率、上覆荷载均能提高格栅极限拉伸强度,其中上覆荷载在较小拉伸速率时对格栅的应变影响较大,其由8%减少到5.2%;靠近土工格栅筋土界面区域的土体位移最大,已初步形成筋土拉伸剪切位移带,上覆荷载越大,筋土拉伸剪切位移带的位移越小;随着土工格栅拉伸变形的增加,逐渐形成了筋土界面区域疏密相间的孔隙率分布特征,筋土上下界面部分区域的孔隙率变大,界面砂土发生剪胀现象。

In order to study the tensile properties of the geogrid,a discrete element model of geogrid tensile test under lateral confinement was established using PFC3D.The sensitivity of the tensile speed and overlying load to the tensile properties of the geogrid were analyzed.The interaction between the soil displacement and tensile deformation of the geogrid under the lateral restraint was discussed.The development of the porosity at the interface between the reinforcement and the soil was revealed.The results show that the ultimate tensile strength of the geogrid can be increased by increasing the tensile speed and the overlying load,while the overlying load has a larger effect on the strain of the geogrid at a small tensile speed,decreasing from 8%to 5.2%;the soil displacement near the interface of the geogrid and the reinforced soil is the largest,and the tensile and shear displacement zone of the reinforced soil appears.The larger the overlying load,the smaller the displacement of the tensile and shear displacement zone.With the increase of tensile deformation of the geogrid,porosity distributes evenly at the interface between the geogrid and reinforced soil.The porosity of the upper and lower interfaces of the tendons increases,and the interface sand dilates.