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为了研究砂性土中钢管桩复合基础的承载特性,设计了模型桩系列试验。结果表明:对于单桩复合基础,封桩前阶段的荷载全部直接由承台底砂土承担,封桩后阶段桩体达到极限承载力之前,桩体分担的荷载占荷载增量的73.5%～92%,当桩的承载能力达到极限后,随着荷载的继续增加,桩分担的荷载比例较之前衰减明显,而土体分担的荷载比例增加。钢管桩八桩复合基础中,桩身轴力在桩身上部的衰减梯度明显小于中下部,角桩衰减速率最大,边桩次之;桩身摩阻力自上而下逐渐发挥,桩顶以下1.55 m处摩阻力达到最大;每级荷载作用下,角桩的侧阻力大于边桩。钢管桩群桩复合基础的竖向承载力远大于相对应的高承台群桩承载力。
In order to study the bearing characteristics of composite foundation of steel pipe pile in sandy soil, a series of model pile test was designed. The results show that for the composite foundation of single pile, the loads in the first stage of the sealing pile are all directly borne by the bottom soil of the bearing platform. Before the pile reaches the ultimate bearing capacity, the load shared by the pile accounts for 73.5% 92%. When the load carrying capacity of the pile reaches the limit, as the load continues to increase, the proportion of the load shared by the pile declines obviously compared with the previous one, while the proportion of load shared by the soil increases. Among the eight composite foundations of steel pipe piles, the attenuation gradient of the axial force of the pile body in the upper part of the pile body is obviously smaller than that in the middle and lower part. The decay rate of the angle piles is the largest, followed by the side piles. The frictional resistance of the piles gradually develops from top to bottom, At 1.55 m, the frictional resistance reaches the maximum. Under each load, the lateral resistance of the corner piles is greater than that of the side piles. The vertical bearing capacity of steel pipe pile group composite foundation is much larger than the corresponding bearing capacity of high pile group pile.