大厚度湿陷性黄土场地群桩基础负摩阻力分析

Analysis of Negative Friction Resistance of Pile Group Foundation in Large Collapsible Loess Site

文中采用有限元仿真方法,分析群桩的桩土沉降、负摩阻力以及桩身轴力。结果表明,群桩的极限荷载承载力为45 kN,所有桩的桩周土沉降量均随着深度的增加而不断降低。当距桩顶深度小于20 m时,中心桩的桩周土沉降最小;当距桩顶深度大于20 m时,中心桩的桩周土沉降最大。浸水后的角桩、边桩和中心桩的摩阻力分别比浸水前高40%、38%、33%。浸水前,桩身轴力随着桩顶深度的增加呈现不断降低的趋势;浸水后,桩身轴力随着桩顶深度的增加呈现先增加后降低的趋势。距桩顶最远处,浸水后角桩、边桩和中心桩的桩身轴力均高于浸水前的桩身轴力。

In order to analyze the negative friction resistance of pile group foundation before and after flooding in loess area,finite element simulation method is used to analyze the pile soil settlement,negative friction resistance and axial force of pile group.The results show that the ultimate load capacity of pile group is 45 kN;The soil settlement around pile of all piles decreases with increasing depth.When the depth from pile top is less than 20 m,the soil settlement around pile of central pile is the smallest.When the depth from the pile top is greater than 20 m,the soil settlement around the central pile is the largest.The friction resistance of corner pile,side pile and center pile after water immersion is 40%,38%and 33%higher than that of front corner pile,side pile and center pile respectively.The axial force of pile body decreases with the increase of pile top depth before water immersion,while the axial force of pile body increases first and then decreases with the increase of pile top depth after water immersion.The axial force of corner pile,side pile and center pile after water immersion is higher than that before water immersion.