带加强节点双向土工格栅的拉拔试验研究

Pull-out tests of biaxial geogrid with strengthening nodes

在传统双向土工格栅的节点上设置一定厚度的加强节点,以形成具有立体加筋效果的带加强节点土工格栅。通过室内拉拔试验,研究了带加强节点土工格栅筋-土界面作用特性,探讨了横肋间距和加强节点厚度对极限拉拔阻力的影响。结果表明,拉拔曲线在法向应力较小时出现峰值,法向应力较大时表现出应变硬化的特征。带加强节点土工格栅的极限拉拔阻力较传统土工格栅都有一定程度的提高,且随着横肋间距的增大而减小,随着加强节点厚度的增加而线性增大。基于试验结果分析极限拉拔阻力的组成发现,随着横肋间距的增大,极限拉拔阻力的主导作用力由横肋极限端承阻力转变为筋-土界面间的极限摩阻力。

In order to obtain a new reinforced material which has the effect of three-dimensional reinforcement, strengthening nodes are set up at the intersections of conventional biaxial geogrid. A series of pull-out tests of geogrid with strengthening nodes were carried out to study the interaction characteristics between strengthening nodes and the sand in the laboratory. The influences of rib spacing and strengthening node height on ultimate pull-out resistance were also discussed. The results show that pull-out resistance-displacement curve reaches the peak value when the normal stress is low, while it exhibits strain harden characteristic when the normal stress becomes high. The ultimate pull-out resistance of geogrid with strengthening nodes is larger than the conventional geogrid＇s. Moreover, it decreases as the rib spacing increases, whereas it rises with the increase of strengthening node height linearly. Based on the pull-out test results, the components of ultimate pull-out resistance were analyzed. It is found that the dominant force of ultimate pull-out resistance changes from bearing resistance of the transverse ribs to frictional resistance between ribs and the sand with the rib spacing increasing.