The existing studies have been primarily focused on the lateral behavior of large-diameter stubby pile or small-diameter slender pile in sand, with little attention paid to large-diameter slender pile. This study presents a unique series of centrifuge tests on monotonic and cyclic lateral behavior of heavily instrumented large-diameter slender piles in medium dense sand. Two typical length to diameter ratios (L/D) are considered with the same length (L = 60 m) but different diameters (D = 4 and 6 m). It is found that the lateral behaviors of large-diameter slender pile, including its monotonic p-y response, cyclic accumulation of lateral displacement and cyclic stiffness evolution, are marginally different from those of small-diameter slender piles, but significantly deviate from the large-diameter stubby piles. This may suggest the longstanding argument of ‘diameter effect’ is relatively minor, while the lateral behavior of monopile in sand is more significantly governed by the relative pile-soil stiffness. The API (2011) non-conservatively predicts both stiffness and capacity of the large-diameter slender piles, leading to development of a new p-y formulation. These centrifuge testing results form a unique database to support development of new design methods for large-diameter slender piles, and to verify advanced numerical analyses involving cyclic models.

现有的研究主要集中在大直径短桩或小直径细长桩在沙子中的侧向性能，而很少关注大直径细长桩。这项研究提出了一系列独特的离心试验，这些试验对中等密度沙子中重载的大直径细长桩的单调和循环侧向性能进行了测试。两种典型的长度与直径之比（L / D）被认为具有相同的长度（L  = 60 m）但具有不同的直径（D = 4和6 m）。发现大直径细长桩的侧向行为，包括其单调py。响应，横向位移的循环累积和循环刚度演化与小直径细桩略有不同，但与大直径短桩却有显着差异。这可能表明长期以来，“直径效应”的论点相对较小，而在沙子中的单桩的侧向行为更受桩土相对刚度的支配。API（2011）非保守地预测了大直径细长桩的刚度和承载能力，从而开发了一种新的py配方。这些离心机测试结果形成一个独特的数据库，以支持开发大直径细长桩的新设计方法，并验证涉及循环模型的高级数值分析。