膨胀土地基载体桩承载力特性数值分析

NUMERICAL SIMULATION ANALYSIS OF BEARING CAPACITY CHARACTERISTICS OF CARRIER PILE IN EXPANSIVE SOIL FOUNDATION

为研究载体桩在膨胀土地基中的承载变形性状,基于极限平衡原理,推导出了载体桩的抗拔承载力公式。考虑含水率对地基土弹性模量的折减影响,应用有限元模型分析了下压和上拔荷载下载体桩的承载特性随土体含水率的变化规律,结果表明随着膨胀土含水率的增加,载体桩的极限抗压和抗拔承载力下降均较明显,含水率相同的抗压桩承载力大于抗拔桩。不同含水率条件下,桩身轴力均随着深度的增加而减小,抗拔桩在桩端处有轴力急剧减小的现象,且含水率越高减小的幅度越小;抗压桩的极限侧摩阻力沿桩深度先增大后减小,含水率越高其最大值越靠近桩中部’抗拔桩的极限摩阻力沿桩长逐渐增大,在桩端处有突增的现象,含水率越高突增的幅度越小。

In order to study the bearing deformation behavior of the carrier pile in expansive soil vfoundation,based on the principle of limit equilibrium,the formula of the bearing capacity was derived.Considering the reduction of the elastic modulus of the foundation soil,the finite element model is used to analyze the variation of the bearing characteristics of the pile under load and the load with the soil moisture content.The results show that with the increase of the moisture content,the ultimate bearing capacity of compressive and tension piles are significantly reduced,and the compressive pile with the same water content is greater than that of the tension pile.Under different water content conditions,the axial force of the pile body decreases with increasing depth,the tension pile at the end of the pile decreases sharply,and the higher the water content,the smaller the reduction;the compressive pile ultimate side friction resistance increases first and then decreases along the depth of the pile,as the water content increase,the maximum value is closer to the middle of the pile,the ultimate frictional resistance of tension pile gradually increases along the length of the pile,and a sudden increase at the end of the pile,the higher the moisture content,the smaller the increase.