长江下游某通用码头散货泊位PHC-钢管组合桩钢管桩长度确定

针对长江下游地区某物流通用码头散货泊位处水体较深、软土（淤泥质粉质粘土）较厚等不利岩土工程条件，确定采用PHC-钢管组合桩作为地基基础，而确定组合桩中的钢管桩长度部分尤为重要。为此，在考虑土体软化特点、桩土接触关系、桩身沉降等基础上，采用FLAC3D软件构建了PHC-钢管组合桩—土模型，进而计算了6根PHC-钢管组合桩中不同钢管长度时的桩身极限承载力、轴力、侧摩阻力。结果表明，钢管桩较短时，组合桩的极限承载力较高；改变钢管桩长度，使PHC管桩与钢管桩的接桩部位处于粉质粘土、粉细砂层时，轴力与侧摩阻力变化较大；接桩部位位于持力层时，缩短钢管桩长度会降低整桩极限承载力及接桩部位的侧摩阻力。通过对比分析钢管桩对组合桩桩身极限承载力、轴力、侧摩阻力的影响程度，最终确定组合桩中钢管桩长度5 m时为最优选择。

Determining Length of Steel Pipe Pile for PHC Steel Composite Pile at Bulk Cargo Berth of Common Wharf in Downstream Region of Yangtze River

For the deep water and thick soft soil (silty clay) and other unfavorable geotechnical engineering conditions at the bulk cargo berth of common wharf in the downstream region of Yangtze River, PHC-steel composite pile is used as a foundation. But it is very important to determine the length of steel pipe pile of composite pile. Based on softening of soil, and the contact characteristics of pile-soil and settlement deformation, FLAC3D was used to build pile-soil model of PHC- steel composite pile. And then the ultimate bearing capacity, axial force and lateral friction resistance of 6 PHC-steel composite piles with different length of steel pipe pile were calculated. The results indicate that the shorter steel pipe pile of PHC-steel composite pile has higher ultimate bearing capacity. While the length of steel pipe pile changed, there were quite difference in axial forces and lateral friction resistance when the joint of PHC-steel composite are in silty clay layer and silty fine sand stratum. When the length of steel pipe pile was decreased, the ultimate bearing capacity of the pile and the lateral friction resistance of joint appeared downward trend when the joint of PHC-steel composite pile was in the bearing layer. Through comparative analysis of the ultimate bearing capacity, axial force and lateral friction resistance impact of steel pipe pile, it determined that the length of steel pipe pile of PHC-steel composite pile is 5 m.