五星形混凝土桩是一种新型截面异形桩，由圆截面均匀内切5个圆弧形成，其截面参数主要有被切割圆半径R、切割圆半径r、切割圆弧所对应的外包圆圆心角2x、外包圆弧对应圆心角θ。经截面尺寸优化分析，推导出周长最大化五星形桩和周长面积比最大化五星形桩。为进一步掌握五星形桩承载性能，以砂雨法制作土样，在干砂中进行了4根单桩对比模型试验研究，4根单桩为：周长面积比最大化五星形桩F2、周长最大化五星形桩F1、与F2等截面周长圆桩C1、与F2等截面面积圆桩C2。试验结果表明：与F1相比，F2的桩侧表面积与其相近，极限承载力大致相同，但F2混凝土用量是F1混凝土用量的0.75倍，单位体积混凝土承载力更高，F2为最优的截面尺寸；与等截面面积小圆桩C2相比，F2桩侧表面积是其1.53倍，极限承载力是其2.4倍，显示出在相同混凝土用量下五星形桩F2具有良好的承载性能，截面异性扩大效应明显；与相同截面周长的大圆桩C1相比，F2桩截面面积是其0.44倍，极限承载力是其0.96倍，但F2桩单位体积混凝土承载力是C1桩的2.21倍，显示出更高的承载性价比。各级荷载作用下五星形桩侧摩阻力所占比例在80%以上，特别是F2桩，在90%以上，表现出摩擦桩的特性。研究成果可对五星形桩的工程应用提供一定理论支持。

The five-star-shaped concrete pile is a new type of pile with a special shaped cross-section. It is formed by cutting five circular arcs in a circle pile. The main parameters of the cross section include the radius of the circumcircle R and the corresponding circumcircle central angle θ, the radius of inward cutting circular arc r and the corresponding circumcircle central angle 2x. Through the optimization analysis of the section size, the maximum of the circumference of the five-star-shaped piles and a maximum ratio of perimeter to the area of five-star-shaped piles are derived. To further explore the vertical bearing capacity of five-star-shaped piles, experimental studies are carried out on the comparison of four single piles in the dry sand by the sand pouring method. These four single piles are the maximum ratio of perimeter to the area of the five-star-shaped pile F1, the maximum of the circumference of the five star-shaped pile F2, the round pile C1 with the same perimeter of F2, and round pile C2 with the same cross-sectional area of F2. The following conclusions are drawn from this study. The side surface area of F2 gets close to that of F1, and the ultimate bearing capacity is approximately the same. The concrete dosage of F2 is 0.75 times that of F1, the bearing capacity per concrete is higher, and thus F2 is optimal cross-sectional pile. Compared with C2, the side surface area of F2 is 1.53 times that of C2, and the ultimate bearing capacity of F2 is 2.4 times that of C2. It shows that F2 has better bearing capacity than that the same amount of concrete, and the expansion effect of cross-section is obvious. Compared with C1, F2 pile cross section area is 0.44 times that of C1, the ultimate bearing capacity is 0.96 times that of C1, and the unit volume concrete bearing capacity of F2 pile is 2.21 times that of C1, which exhibits higher load cost performance. At all levels of load, the ratio of the lateral friction of the five star-shaped piles is more than 80%, especially F2, and the proportion of side friction resistance is above 90%, which shows the characteristics of friction pile. This study provides theoretical support for the engineering application of five-star-shaped piles.