加强节点布置方式对双向土工格栅拉拔特性的影响

Influence of Strengthened Node Arrangement on Pull-Out Characteristics of Biaxial Geogrid

随着土工加筋技术的发展,加筋材料形式趋向于三维化,通过在普通双向土工格栅横、纵肋交叉节点处布置一定厚度的加强块,形成了具有三维加筋效果的加强节点土工格栅,节点布置方式分为节点总厚度相等的上下双侧布置和上侧单侧布置两种方式.为了探索筋土界面之间复杂的相互作用机制,开展了一系列室内拉拔试验,探究了加强节点布置方式对筋土界面特性的影响,基于刺入剪切破坏理论分析了加强节点的作用机理并得到了极限拉拔阻力理论模型.结果表明:加强节点土工格栅的极限拉拔阻力与法向应力、节点厚度呈正相关关系.同一法向应力下,与普通土工格栅相比,两种节点布置方式工况的极限拉拔阻力均有一定程度的提高,提高率最高分别为118.33%和96.73%,表现为界面似摩擦系数、似黏聚力和综合摩擦角同时增加,且等节点厚度时上下双侧布置方式优于上侧单侧布置方式.基于刺入剪切破坏模式的理论值与试验值之间误差小于10%,加强节点显著提高了格栅的拉拔阻力.

With the development of the geotechnical reinforcement technology,the form of reinforcing materials tends to be three-dimensional.Strengthened blocks of a certain thickness are attached to the joints of the longitudinal and transverse ribs of an ordinary biaxial geogrid so that it becomes a geogrid with strengthened nodes with a three-dimensional reinforcement effect.The layout of the strengthened nodes is divided into two types:upper and lower bilateral arrangement and upper unilateral arrangement,in which the total node thickness was the same.To explore the complex interaction mechanism of the reinforced soil interface,a series of indoor pull-out tests are conducted to investigate the influence of strengthened node arrangement on the characteristics of the reinforced soil interface.Based on the punching shear failure mechanism,the reinforcing mechanism of strengthened nodes is analyzed and the theoretical model of ultimate pull-out resistance is obtained.The results show that the ultimate pull-out resistance of the geogrid with strengthened nodes has a positive correlation with normal stress and node thickness.At the same normal stress,compared with the ordinary geogrid,the ultimate pull-out resistance of the two layout types of strengthened nodes is improved to some extent.The highest improvement rates are 118.33%and 96.73%,respectively.The interface apparent friction coefficient,pseudo cohesion,and comprehensive friction angle increase simultaneously.The ultimate pull-out resistance of the upper and lower bilateral arrangement is bigger than that of the upper unilateral arrangement.The error between the theoretical value based on the punching shear failure mode and the experimental value is less than 10%,and the strengthened node significantly improves the pull-out resistance of the geogrid.