土工格栅纵横肋的筋土承载特性分析
Bearing characteristics of reinforced soil with longitudinal and transverse ribs of geogrids
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摘要: 为研究土工格栅纵横肋与砂土的界面受力特性,进行了不同法向压力的格栅拉拔试验,分别设计了横向与纵向剪除横肋的6种拉拔试验工况,研究横肋减少对格栅受力、拉拔阻力峰值和位移及似摩擦系数的影响,并分别对比了整体剪切和刺入剪切破坏模式下的格栅拉拔阻力,揭示格栅筋土界面的相互作用机理。结果表明,随着横肋的减少,格栅拉拔阻力和似摩擦系数不断地变小;横肋沿横向减少的格栅最大拉拔阻力大于横肋沿纵向减少的最大拉拔阻力,完整横肋有助于筋土界面的加筋作用的充分发挥。理论计算格栅界面摩擦力约为18%~19%的试验拉拔阻力,而试验获得的格栅界面摩擦力与试验拉拔阻力的比值为29%~33%,横肋与土体挤压咬合产生的承载力分量占了总拉拔阻力的67%~71%,横肋极大提高了土工格栅的拉拔阻力。Abstract: In order to study the stress characteristics of interface between longitudinal and transverse ribs of geogrids and sand, the pullout tests are carried out under different normal pressures. Six pull-out test conditions are designed by trimming ribs in the transverse and longitudinal directions. The effects of geogrid stress, pullout resistance peak and displacement and apparent friction coefficient are studied owing to reduction of transverse ribs, and the pullout resistances under two modes of general shear failure and punching shear failure are compared, which reveales the interaction mechanism of reinforced soil interface. The results show that with the decrease of the transverse ribs, the pullout resistance and apparent friction coefficient of geogrids are decreased. The maximum pullout resistance of geogrids that the ribs are reduced in the transverse direction is larger than that of the ribs reduced in the longitudinal direction. The full transverse ribs can contribute to the reinforcement effect of the interface. The skin friction component of theoretical calculation is about 18%~19% of the experimental pullout resistance, while the experimental skin friction component is about 29% -33% of the experimental pullout resistance, and the bearing capacity component of the transverse ribs accounts for 67%~71% of the total pullout resistance. The transverse ribs greatly improve the pullout resistance of geogrids.