填芯复合固化土预制桩界面摩擦特性

Interface friction characteristics of precast pile with core-filled composite solidified soil

摘要:

填芯复合固化土预制桩由芯桩和固化土挤压形成的预制桩组成,为了探究芯桩预制桩界面的摩擦特性对固化土预制桩承载能力的影响,以环形剪切试件模拟芯桩预制桩界面的接触情况,研究了芯桩预制桩接触面的摩擦特性。试验结果表明:芯桩预制桩界面极限摩阻力随芯桩直径的增加而增大;芯桩预制桩界面黏结系数随填芯材料抗压强度的增加而增大,黏结系数建议取值范围为0.02~0.10;芯桩预制桩界面存在初始摩阻力,剪切过程中界面摩阻力变化存在弹性阶段、脆性破坏阶段和黏结滑移阶段,界面破坏模式为类脆性破坏。采用指数模型和反双曲线模型对界面摩阻力和相对位移的散点图进行拟合,获得了考虑初始摩阻力τ_c的黏结滑移荷载传递模型,可用于填芯复合固化土预制桩受荷的荷载传递规律分析。

Abstract:

To investigate the influence of core-pile interface friction characteristics on the bearing capacity of filled-core composite solidified soil precast piles, this study simulated the core-pile-precast-pile interfacial contact using annular shear specimens and systematically examined the frictional behavior at their interface. The experimental results demonstrated that: The ultimate interfacial frictional resistance increases with core pile diameter enlargement; The bonding coefficient between core pile and precast pile shows a positive correlation with the compressive strength of core-filling materials, with recommended values ranging from 0.02 to 0.10; An initial frictional resistance exists at the interface, and the shear-induced friction evolution exhibits three distinct phases-elastic deformation phase, brittle failure phase, and bond-slip phase, presenting a quasi-brittle failure mode. Through curve fitting of the interfacial shear stress versus relative displacement scatter plots using exponential and inverse hyperbolic models, a bond-slip load transfer model incorporating initial frictional resistance (τ_c) was established. This model effectively characterizes the load transfer mechanism in filled-core composite solidified soil precast piles under loading conditions. The proposed methodology provides theoretical support for analyzing the bearing behavior and interfacial interaction mechanisms of this novel pile foundation system.