隔水导管复合群桩竖向承载特性

基于有限元方法对阵列排布的隔水导管组成的群桩基础开展竖向载荷作用下的破坏模式研究，分析不同井口间距、桩数、桩径和桩长下隔水导管复合群桩基础的极限承载力和轴向载荷传递规律，结合隔水导管的结构特点，推导适用于隔水导管复合桩的群桩效应系数计算公式。研究表明：隔水导管复合桩群桩效应系数随距径比Sa/D1的增大、桩数N的减小、桩径D1的增大及不排水强度Su的增大而增大；增加变截面以下桩长L2，可提高复合群桩中心桩承载力发挥程度。与相同工况普通钢管桩群桩基础相比，隔水导管复合群桩基础的侧摩阻力发挥更加充分，群桩效应系数更高。

Vertical Bearing Characteristics of Conductor Composite Piles

Based on the finite element method, a group of pile foundations composed of arrayed conductors are studied for the failure mode under vertical loads. The ultimate load capacity and rule of axial load transfer under different wellhead distances, pile numbers, pile diameters and pile lengths are analyzed. Combined with the structural characteristics of the conductor, the formula for calculating the group pile effect coefficient for conductor composite piles is derived. The research shows that: the pile group effect coefficient of the conductor pipe increases with the increase of the distance diameter ratio Sa / D1, decrease of the number of piles N, increase of the pile diameter D1 and increase of the undrained strength Su; the bearing capacity of the central pile increases with the pile length below the variable section L2. Compared with the ordinary steel pipe pile group foundation under the same working condition, the lateral friction resistance of the conductor composite pile group foundation is exerted more fully, and the group pile effect coefficient is higher.