颗粒形状影响下碎石-桩界面侧摩阻力计算研究

Calculation of Side Friction at Gravel-pile Interface Under Influence of Particle Shape

提出了一种颗粒形状影响下碎石地层中碎石-桩界面侧摩阻力计算方法,使用可描述应力应变硬化及软化的界面剪切函数计算单桩侧摩阻力;为探究碎石颗粒形状对界面剪切应力应变行为的影响,制备了八种碎石,使用图像处理的方法获得碎石的形状参数(长细比、凸度及球度);考虑三种形状参数的权重,提出了一种改进的颗粒整体规整度的计算方法;建立不规则碎石-桩界面剪切的离散元模型,探究了颗粒整体规整度与临界界面摩擦角、界面剪切临界状态之间的关系.结果表明:颗粒整体规整度与临界界面摩擦角之间存在很强的线性关系,且整体规整度只改变临界状态线的截距.在桩侧摩阻函数中考虑颗粒形状的影响,并求解碎石地层中竖向荷载下不同深度桩基础桩侧摩阻力.将室内试验结果与采用本文提出的考虑颗粒形状的桩侧摩阻计算方法获得结果进行对比,验证了本文所提出方法的适用性及准确性.

In this paper,a method for calculating the side friction of gravel pile interface in gravel stratum under the influence of particle shape is proposed.The side friction of a single pile is calculated by using the interface shear function which can describe stress-strain hardening and softening.In order to consider the influence of gravel particle shape on interfacial shear stress-strain behavior,eight kinds of gravel are prepared in this paper.The shape parameters(slenderness ratio,convexity and sphericity)of gravel are obtained by the image processing method.Considering the weight of three shape parameters,an improved calculation method of overall particle regularity is proposed.The discrete element model of irregular gravel pile interface shear is established to explore the relationship between the overall regularity of particles and the critical friction angle of interface and the critical state of interface shear.The results show that there is a strong linear relationship between the overall regularity of particles and the critical friction angle,and the overall regularity only changes the intercept of the critical state line.The influence of particle shape is considered in the pile side friction function,and the pile side friction of pile foundation at different depths under vertical load in gravel stratum is solved.The indoor test results are compared with the results obtained by the pile side friction calculation method considering particle shape proposed in this paper,which verifies the applicability and accuracy of the method proposed in this paper.