超静定土工格栅凸节点极限被动摩阻力计算方法

Calculation Method for Limit Passive Frictional Resistance Induced by Convex Nodes of Hyperstatic Geogrid

筋土界面强度是决定加筋土结构承载力和稳定性的重要因素之一。诸多研究表明,在传统土工合成材料的基础上设计附加结构形成的超静定土工合成材料可以有效提升筋土界面强度。然而,不同形式的附加结构对筋土界面强度的增强机理仍有待开展进一步研究。为此,以一种带有凸起节点结构的高摩阻超静定土工格栅(HRHG)为研究对象,在考虑HRHG节点两侧土体抗剪强度的基础上,基于极限平衡状态下的对数螺旋曲线滑裂面假设,建立了HRHG节点在极限状态下与土相互作用的力学解析模型。针对HRHG节点在筋土相互作用中的极限被动摩阻力进行了理论分析,给出了极限状态下HRHG节点被动摩阻力的计算方法;同时利用自主研发的大型直剪仪,在不同法向压力(30、50、80 kPa)下开展了以HRHG和普通双向格栅为研究对象,以低液限粉土为回填土的筋土直剪试验。试验结果对比表明:HRHG节点将筋土界面表观黏聚力和界面摩擦角分别提高了35.6%和14.3%,说明HRHG节点可以有效地提高筋土界面剪切强度。通过对比试验结果与理论推导结果,验证了所提出的极限状态下HRHG节点被动摩阻力计算方法的有效性,并进一步对计算方法进行了修正,以期为HRHG在实际加筋土结构中的应用与设计提供相关借鉴和参考。

Geosynthetic-soil interaction is a critical factor influencing the bearing capacity and stability of geosynthetic-reinforced soil structures.Several studies have shown that hyperstatic geosynthetics,designed with additional structures based on traditional geosynthetics,effectively improve the strength of geosynthetic-soil interfaces.However,the improvement mechanism of additional structures of hyperstatic geosynthetics still requires further investigation.In this study,high-resistant hyperstatic geogrids(HRHGs)designed with convex nodes were employed.In the limit equilibrium state,a logarithmic spiral-curved-surface failure mechanism was assumed by incorporating the lateral interfacial shear strength of HRHG nodes.In addition,a mechanical analytical model of the HRHG nodes was established to improve the interfacial strength of the reinforced soil.The model simulated the passive resistance of HRHG nodes in limit geogrid-soil interaction,and a method for calculating the ultimate passive resistance of HRHG nodes was developed.Based on a self-developed large-scale direct shear apparatus,direct shear tests on the HRHG and traditional bidirectional geogrids were performed with low-liquid-limit silt under different normal pressures(30,50,and 80 kPa).The test results show that the convex nodes of HRHG increase the apparent cohesion and friction angle of geogrid-silt interfaces by 35.6% and 14.3%,respectively.The comparison between the test and calculation results validates the proposed calculation method for determining the ultimate passive resistance of HRHG nodes.Furthermore,the calculation method was revised based on the test results,providing a reference for the design and practical application of HRHGs.