基于极限抗力的微型单桩加固边坡承载失效模式研究

Research on Failure Mode of Slope Reinforced by Single Micro-pile Based on Ultimate Resistance

基于混凝土管桩推导了微型钢管桩的极限抗弯承载力公式。基于此,采用数值分析手段建立微型单桩加固土质边坡的极限抗力分析模型,分析加固体系的变形以及破坏过程和失稳机理。研究表明:(1)微型桩发生弯曲破坏后,抗弯能力并未消失且保持不变,转而发挥桩身的抗拔能力;(2)滑面附近土压力最大,滑面附近以下的土体起主要抗力作用;(3)总抗力可认为是由滑面抗剪强度和最大轴力的水平分量组成;(4)破坏模式可分为4个阶段,即滑面剪切阶段、桩体挠曲阶段、桩体抗拔阶段、整体剪切破坏阶段。文中的研究成果可为微型桩在边坡加固工程中的设计和安全评价提供理论依据。

The formula of ultimate flexural capacity of micro steel pipe piles is derived based on concrete pipe piles,thereafter the numerical analysis method is used to establish the ultimate resistance analysis model of the single micro-pile reinforced soil slope,analysis is conducted in terms of the earth pressure,internal force of the pile body,deformation of the reinforcement system,as well as the failure process and the instability mechanism.The research shows that:(1)after the bending failure of the micropile,the bending resistance does not disappear and remains unchanged,and the pile body’s pull-out resistance is turned to be achieved.(2)The soil pressure is the highest near the slip surface,and the soil below the slip surface plays a major role in resistance.(3)The total resistance can be regarded as the horizontal component of the shear strength and the maximum axial force of the sliding surface.(4)The failure mode can be divided into four stages:the slip surface shear stage and pile deflection stage,the pile uplift stage,and the overall shear failure stage.The research results of this paper can provide a theoretical basis for the design and safety evaluation of micro-piles in slope reinforcement.