Pile foundations may experience torsional loads induced by eccentric horizontal loads arising from wind, wave or ship collisions in offshore environment, in addition to axial loading from the supported superstructures. 1g model experiments were conducted in the laboratory to investigate the behaviour of single piles under independent vertical (V) and torsional load (T), and combined vertical-torsional (V-T) loads. Four types of layered soil profile of SC (sand-over-clay), CS (clay-over-sand), SCR (sand-over-clay-over-rock) and CSC (clay-over-sand-over-clay) were considered. The vertical load-displacement response, the torsion-rotation response, and the load transfer under two loading sequences (i.e., V→T and T→V) were observed. For the piles embedded in SC and CS, the bearing capacity envelopes in V-T plane and their simplified calculation formula were obtained as a design reference for engineers. The results indicate that the response of piles subjected to independent loading is substantially different from combined loading, and the soil profile and the load sequence have a significant effect on the bearing behaviour of piles. Compared with pure torsional pile, the ultimate torsional bearing capacity of the piles in SC under the combined V→T loading decreases by about 13-25%. However, the ultimate torsional bearing capacity of the piles in CS and SCR under the combined V→T loading increases by about 39-69% and 2%, respectively. In comparison to independent vertically loaded pile, the ultimate vertical bearing capacity of the piles in SC, CS and CSC under the combined T→V loading decreases by about 3% to 16%. This study shows that a complex interaction of vertical and torsional loads in various layered soils needs to be considered in a practical design.

除了来自支撑的上部结构的轴向载荷外，桩基还可能承受由海上环境中的风，浪或船舶碰撞引起的偏心水平载荷引起的扭转载荷。在实验室中进行了1 g模型实验，以研究独立竖向（V）和扭转载荷（T）以及竖向扭转（V - T）组合载荷下单桩的行为。SC（砂土），CS（砂土），SCR（砂土）以及CSC（砂土）四种类型的分层土壤剖面被认为是。垂直荷载-位移响应，扭转扭转响应和两个荷载序列下的荷载传递（即，观察到V → T和T → V）。对于嵌入SC和CS的桩，获得了V - T平面的承载力包络线及其简化的计算公式，为工程师设计参考。结果表明，独立荷载作用下桩的响应与组合荷载有很大不同，土的剖面和荷载顺序对桩的承载特性有显着影响。与纯扭力桩相比，组合V → T下SC中桩的极限抗扭承载力负载减少约13-25％。但是，在组合的V → T载荷下，CS和SCR中桩的极限抗扭承载能力分别增加了约39-69％和2％。与独立的垂直荷载桩相比，在组合的T → V荷载作用下，SC，CS和CSC中桩的最终竖向承载力下降了大约3％至16％。这项研究表明，在实际设计中需要考虑各种层状土壤中竖向和扭转载荷的复杂相互作用。