土工格栅加筋砂土中水平锚板抗拔特性试验研究

Experimental study of pullout behavior of horizontal anchor plates in geogrid reinforced sand

土工格栅加筋能够有效改善锚板的抗拔承载力,然而锚板在上拔过程中的破坏机制及其影响因素尚需进一步研究。针对砂土中水平锚板的抗拔特性,开展了多组锚板上拔试验,分析了砂土密实度、锚板埋深、土工格栅布设层数和位置等因素的影响,结合粒子图像测速(particle image velocimetry,简称PIV)技术探究了锚板周边土体的变形破坏机制。研究结果表明:单层接触式格栅加筋对锚板的抗拔承载力有明显的提升,且其对土体性能的改善优于非接触式格栅加筋情况,其原因与土工格栅变形量和上覆土体重力有关;当采用双层土工格栅加筋时,下层格栅可充分发挥限制土体侧向变形和均化应力分布的作用,上层格栅相对而言贡献不大;采用土工格栅加筋后,锚-土界面附近土体的变形模式发生了明显的变化,其破坏面相比未加筋前向内侧收敛,且剪应变分布更为均匀。

Geogrid reinforcements can effectively improve the pullout capacity of anchor plates,but the failure mechanism and influencing factors during the uplift process need to be further investigated.In this paper,a series of uplift tests was carried out on horizontal anchor plates in sand to investigate their pullout characteristics,and the influence of various factors was analyzed,including sand density,anchor embedment depth,and number of geogrids and their locations.The particle image velocimetry(PIV)technology was used to explore the deformation and failure mechanism of the sand around anchor plates.The results show that for the pullout capacity of an anchor plate is significantly enhanced by one layer of contact-type geogrid,and the reinforcing effect is better than that with non-contact geogrid.This phenomenon is associated with mobilized friction of the geogrid and the increased weight of sand within the failure surface.When two layers of geogrids are installed,the lower geogrid plays a dominant role in restricting the lateral soil deformation and homogenizing the stress distribution,and the contribution of the upper geogrid is relatively low.Whether geogrids are applied or not will alter the deformation mechanism at the anchor-sand interface.With geogrid reinforcement,the failure surface converges inward,and the shear strain distribution is more uniform.