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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5m时为最优选择。
In view of unfavorable geotechnical conditions such as thicker water body and thicker soft soil (silt silty clay) at a bulk cargo berth of a general logistics terminal in the lower reaches of the Yangtze River, it is determined that the PHC-steel pipe composite pile is used as the foundation of foundation and the composite pile Part of the length of the steel pipe is particularly important. Therefore, based on the characteristics of soil softening, the contact relationship between pile and soil, and the settlement of pile body, the PHC-steel-concrete composite pile-soil model was constructed by using FLAC3D software, and then the different lengths of steel pipes in 6 PHC- When the ultimate bearing capacity of the shaft, axial force, lateral friction. The results show that the ultimate bearing capacity of the composite piles is high when the steel pipe piles are short, and when the length of the steel pipe piles is changed so that the connection between the PHC pipe piles and the steel pipe piles is silty clay and silty sand, the axial force And the lateral friction resistance changes greatly. When the piles are located in the bearing layer, shortening the length of the steel pipe piles will reduce the ultimate bearing capacity of the piles and the side friction of the piles. By comparing and analyzing the influence of steel pipe piles on the ultimate bearing capacity, axial force and side friction of composite piles, it is the optimal choice when the length of steel pipe piles in composite piles is finally determined to be 5m.