土工格栅横肋对加筋砾石强度与变形特性的影响

Influence of geogrid transverse members on strength and deformation behavior of reinforced granular soil

土工格栅广泛应用于各类加筋土结构工程实践,在这些实际的加筋土结构中,加筋土体一般处于平面应变状态。为了更详尽地描述平面应变状态下土工格栅加筋土的复合力学性状,加深对土工格栅加筋机制的认识,通过以砾石和具有不同横肋数量的土工格栅为研究对象,进行大型双轴压缩试验,探究了平面应变状态下土工格栅横肋对加筋土强度和变形特性的影响。试验结果表明:土工格栅显著提高了加筋土试样的最大轴向应力,最大轴向应力随土工格栅横肋数量的增加而增大;基于数字图像相关(DIC)技术,获得了同一围压下未加筋土和各加筋土试样土颗粒的位移和旋转情况,直观地展现了土工格栅的加筋效果;加筋土试样中土工格栅在双轴压缩荷载作用下的纵向拉伸应变分布规律呈现中部最大、朝格栅试样两端递减的规律;在相同轴向应变条件下,上层格栅的拉伸应变略大于下层格栅的拉伸应变;在相同轴向应力作用下,土工格栅的纵向拉伸应变随横肋数量的增加而减小。

Geogrid has been widely used in various practical reinforced soil structures, and are more or less in plane strain conditions. In order to describe the compound stress-strain behavior of geogrid reinforced soil under plane strain conditions and to improve the understanding of geogrid reinforcement mechanisms, large-scale biaxial compression tests were carried out on granular soil and geogrids with different numbers of transverse members. The influence of geogrid transverse members on the strength and deformation behavior of reinforced soil was investigated. The experimental results showed that the maximum vertical stresses of reinforced soil specimens were greatly improved using geogrid reinforcements. With increasing number of geogrid transverse members, the maximum vertical stress of reinforced soil specimen increased. Using the Digital Image Correlation （DIC） method, the displacements and rotations of soil particles in the unreinforced and reinforced specimens under the same confining stress were achieved to visualize the geogrid reinforcing effects. Moreover, the maximum longitudinal geogrid tensile strain in each reinforced specimen under biaxial compression loads occurred in the middle part of the geogrid and decreased gradually from the middle part to the side boundaries of the geogrid. Under the same vertical strain, the tensile strains within the upper geogrids were slightly larger than those within the lower geogrids, The longitudinal tensile strains decreased with increasing number of geogrid transverse members under the same vertical stress.