Investigation of cyclic pile-sand interface weakening mechanism based on large-scale CNS cyclic direct shear tests
Investigation of cyclic pile-sand interface weakening mechanism based on large-scale CNS cyclic direct shear tests
复制标题
基于大型CNS循环直剪试验的循环桩-砂界面弱化机理研究
DOI：
10.1016/j.oceaneng.2019.106650
复制
发表时间：
2019-12-15
影响因子：
5
通讯作者：
Liu, J.
中科院分区：
文献类型：
--
作者：
Liu, J. W.;Cui, L.;Liu, J.
砂质土中近海桩基在循环荷载作用下的承载力破坏通常是由桩-砂界面循环滑动引起的土体强度降低引起的。本文设计了大型恒法向刚度（CNS）循环直剪装置模拟该滑动机制，有效剪切面积为0.14 m(2)。随后研究了两种常见类型的桩（混凝土桩和钢桩）在不同围压和循环变形幅值下的循环桩-砂界面行为。对试验结果进行了分析，包括诱导剪切/法向应力-位移特性、应力路径特性和桩砂界面颗粒分布。通过对剪切/正应力幅值的循环衰减、强度折减和颗粒破碎的研究，进一步详细研究了相关的桩-砂界面循环弱化机制。此外，试验结果突出了初始围压、循环剪切变形幅值和桩面粗糙度对所研究的桩-砂界面循环弱化机制的影响。
Bearing capacity failures of offshore pile foundations under cyclic loads in sandy soils are usually initiated by soil strength reduction due to cyclic pile-sand interface sliding. In this paper, a large-scale constant normal stiffness (CNS) cyclic direct shear apparatus is designed to simulate this sliding mechanism, with an effective shearing area of 0.14 m(2). The cyclic pile-sand interface behaviour of two common types of piles (concrete and steel piles) is subsequently investigated under different confining pressures and cyclic deformation amplitudes. The experimentally obtained results, including the induced shear/normal stress-displacement behaviour, stress path behaviour and particle distribution at the pile-sand interface, are analysed. This further leads to a detailed study for the associated pile-sand interface cyclic weakening mechanism, through the investigations of cyclic attenuation of shear/normal stress amplitude, strength reduction and particle crushing, respectively. Furthermore, experimental results highlight the effect of initial confining pressure, cyclic shear deformation amplitude and pile surface roughness on the investigated pile-sand interface cyclic weakening mechanism.