关键词: 土工格栅, 拉拔试验, 法向应力, 界面特性, 似摩擦系数

Abstract:

[Objective] Geogrids are widely applied in high loess slopes engineering due to their advantages of strong overall durability, high tensile strength, and corrosion resistance. The interface friction coefficient between the reinforcement and soil is a crucial parameter for pull-out verification of reinforced soil slopes, and its value is influenced by multiple factors. [Method] This study employed an independently developed geosynthetic material tensile pull-out testing system to conduct a series of laboratory pull-out tests on steel-plastic geogrids and remolded loess under varying normal stresses, pull-out rates, and water contents, aiming to investigate the effects of these factors on the friction characteristics of the steel-plastic geogrid-loess interface. [Results] The peak pull-out force of the reinforcement increased with increasing normal stress and decreased with increasing water content, with a maximum value of 18.143 kN. Under different normal stresses, the relationship between pull-out force and displacement at the loading end was divided into four stages,such as linear increase, nonlinear increase, decay, and stabilization. The pull-out force increased with the pull-out rate, and higher pull-out rates corresponded to greater peak pull-out forces. Although the pull-out rate varied, the trend of the pull-out force versus loading end displacement curve remained similar; as the loading end displacement continuously increased, the pull-out force first increased, then decreased, and finally tended to stabilize. The maximum shear stress increased with normal stress and decreased with water content; the influence of normal stress on maximum shear stress weakened gradually as water content increased. The interface cohesion showed a trend of first increasing and then decreasing with rising water content, reaching a maximum of 11.043 kPa at the optimal water content. The apparent friction coefficient decreased with increasing water content and normal stress; when the normal stress was 105 kPa, the apparent friction coefficient was approximately 0.13, which was about one-third to one-half of the recommended standard value. [Conclusion] The pull-out characteristic tests indicate that engineering design should not be evaluated solely based on the apparent friction coefficient, but should also fully consider actual water content, overburden load, and other engineering conditions. The results of this study provide a reference for the structural design of high loess slopes.

Key words: geogrid, pull-out test, normal stress, interface characteristic, apparent friction coefficient