为揭示不同土工格栅嵌入长度L和砂土类型对加筋土界面特性的影响，通过系统开展基于土工格栅嵌入长度L、法向压力σ_v、砂土类型3个关键因素的拉拔试验，深入分析不同工况下土工格栅拉拔阻力峰值、筋土界面强度、土工格栅应变的分布规律及加筋土影响带厚度的演变特征。结果表明：在土工格栅未被拉断的情况下，拉拔阻力峰值随着土工格栅嵌入长度L、法向压力σ_v、砂土平均粒径d₅₀的增大而增大；基于多项式回归模型，建立了拉拔阻力峰值与σ_v、L、d₅₀的函数关系。筋土界面的似黏聚力c随d₅₀增大而增大、随L增大而减小；似内摩擦角φ则与L呈正相关、而受d₅₀影响较小。通过多变量拟合，建立了c、φ与L、d₅₀的函数表达式，以及筋土界面摩擦系数f与L、d₅₀、σ_v之间的函数表达式，为深入理解加筋土相互作用提供了定量分析的依据。土工格栅埋入段应变衰减速率随L的增加而逐渐平缓，BC段到CD段的应变下降占比从L=30 cm时的80%以上降至L=40 cm时的50%~60%。加筋土影响带厚度随着法向压力σ_v和砂土平均粒径d₅₀的增大而增大，格栅嵌入长度L对加筋土的影响带厚度影响不显著。

To investigate the effects of geogrid embedment length L and sand type on the interface behavior of reinforced soil, a series of pullout tests were systematically conducted based on three key parameters: geogrid embedment length L, normal stressσ_v, and sand type. The peak pullout resistance, soil-geogrid interface strength, strain distribution of the geogrid, and thickness evolution of the reinforced soil influence zone were analyzed under various working conditions, and evolution characteristics of the strength of the reinforcement-soil interface. The results show that the peak pullout resistance is enhanced by increasing L, σ_v, and the average particle size of the sand d₅₀ when the geogrid remains intact. A polynomial regression model is developed to express the peak pullout resistance as a function of L, σ_v, and d₅₀. The apparent cohesion c of the soil-geogrid interface is observed to increase with d₅₀ but decrease with L, whereas the apparent internal friction angle φ is positively correlated with L and minimally affected by d₅₀. Functional relationships between c, φ and L, d₅₀, as well as between the interface friction coefficient f and L, σ_v, d₅₀, are established through multivariate fitting methods. The strain decay rate in the embedded geogrid section is found to decrease gradually with increasing L. The strain reduction proportion from the BC to CD segments is reduced from over 80% at L = 30 cm to 50% ~60% at L = 40 cm. The thickness of the reinforced soil influence zone is shown to increase with σ_v and d₅₀, while L exhibits negligible influence on this thickness.