多元荷载作用下软基深水高桩码头结构承载特性研究*

软基深水高桩码头结构受到恶劣外海环境荷载及复杂工作荷载等多元荷载的共同作用。研究表明，船舶撞击荷载是该结构水平向控制荷载，但波浪长期循环荷载作用会引起桩周土体软化，进而导致码头结构在其它荷载作用下承载特性的劣化。鉴于此，首先基于ABAQUS有限元软件建立了深水高桩码头结构-地基土体相互作用的三维弹塑性有限元模型；然后，借助USDFLD子程序实现了同时考虑土体强度弱化和刚度衰减的模拟，进而开展了未考虑土体软化、仅考虑土体强度弱化、仅考虑土体刚度衰减以及同时考虑土体强度弱化和刚度衰减对码头结构承载特性影响的对比分析。研究结果表明，与未考虑土体软化时撞击荷载作用下码头结构安全系数相比，仅考虑土体强度弱化时其值降低14.72%，仅考虑土体刚度衰减时其值降低15.28%，同时考虑土体强度弱化和刚度衰减时其值降低19.44%，且考虑土体软化后桩周土体的塑性应变范围明显增大，极限状态时桩身应力值减小，结构稳定性显著降低。

Bearing characteristics of pile-supported wharf in soft soil ground in deep-water under multiple loadings

The pile-supported wharf structure in soft soil ground in deep-water is subjected to multiple loads such as environment loads and complex work loads.The research shows that ship impact load is the horizontal control load,yet long-term cyclic wave loads will cause the softening of the soft clay soil around piles,leading to the deterioration of the bearing capacity of the wharf structure under other loads.In view of this,a 3D elastoplastic finite element calculation model of wharf structure-foundation soil is established using ABAQUS,in which both weakening of soil strength and degradation of soil stiffness are considered with the help of the USDFLD subroutine.Furthermore,the comparative analyses of the bearing characteristics of the wharf without considering soil softening,only considering weakening of soil strength,only considering degradation of soil stiffness,and both considering weakening of soil strength and decaying of soil stiffness degradation are carried out.The results show that the safety factor of the wharf under the impact load considering the softening of soil strength is reduced by 14.72% when compared with only considering the weakening of the soil strength,and that is reduced by 15.28% when compared with only considering the decaying of soil stiffness,yet that is 19.44% when compared with both considering weakening of soil strength and decaying of soil stiffness.Besides,the plastic deformation range of the soil around the pile is significantly increased and the stress of pile body decreases slightly in the ultimate state,and the structural stability is significantly reduced.