筋箍碎石桩桩–土界面摩擦特性试验研究及离散元模拟

Experimental study and discrete element simulation on interface friction of geo-encased stone columns

筋箍碎石桩复合地基桩–土界面摩擦特性对其荷载传递机理极为重要。首先通过室内大型直剪试验,研究了法向应力、软土含水率、碎石料相对密实度、筋材设置等因素对筋箍碎石桩桩–土界面摩擦特性的影响。在此基础上,采用离散元方法分析了筋材设置、筋材开孔率、筋材抗拉刚度等因素对界面摩擦特性的影响。室内试验及数值分析结果表明:桩土界面抗剪强度随法向应力、碎石料相对密实度、筋材开孔率、筋材抗拉刚度的增大而增大,随软土含水率的增加而降低;界面摩擦系数则随法向应力、软土含水率的增大而减小,随碎石料相对密实度、筋材开孔率的增大而提高,筋材抗拉刚度对其影响较小。

The friction characteristics of the column-soil interface is important to the load transfer mechanism of geo-encased stone columns.In this study,model tests are conducted using a large direct shear device to investigate the effects of the normal stress,water content of soft soil,relative density of stone materials and geosynthetic on the characteristics of the column-soil interface.On this basis,the discrete element method is adopted to study the influences of geosynthetic application,aperture ratio of geosynthetic and geosynthetic stiffness.The results indicate the interfacial shear strength increases with the increase of the normal stress,relative density of stone materials,aperture ratio of geosynthetic and geosynthetic siffness,and deceases with the increase of the water content in soft soil.The interfacial friction coefficient decreases with the increase of the normal stress and water content in soft soil,and increases with the increase of the relative density of stone materials and the aperture ratio of geosynthetics.The influences of geosynthetic stiffness are insignificant to the interfacial friction angle.