箱筒型基础防波堤动力稳定性的有限元分析

Finite element analysis for dynamic stability of bucket foundation breakwater

结合天津港防波堤延伸工程,采用Lanczos法,对箱筒型基础防波堤和地基相互作用系统进行了三维有限元模态分析,得出体系自振周期远离波浪力的激励周期,该结构在波浪动荷载作用下不会因发生共振而失稳;建立了箱筒型基础防波堤动力稳定性的三维弹塑性有限元分析方法,得出考虑结构动力特性时,箱筒型基础防波堤动力稳定性安全系数小于静力稳定性安全系数,但结构变位模式和地基破坏模式与按静力有限元计算的结果是一致的。结构运动模式为绕着筒底以下某点发生转动,地基破坏模式为海侧和陆侧的土体自筒底到地表形成的塑性剪切应变贯通区。海侧土体发生主动破坏,陆侧土体发生被动破坏。该研究成果可为这种结构的设计和应用提供借鉴和参考。

According to the project of extending breakwaters in Tianjin Port,a 3D finite element model was used in modal analysis based on the Lanczos method for the system of bucket foundation breakwater and soil foundation.And it is resulted that the longest natural period of vibration of the system is far away from the wave force period,so the structure will not be instable for resonance under the dynamic wave load.A 3D elastic-plastic finite element model was established for dynamic stability analysis of bucket foundation breakwater.The results show that the dynamic stability safety factor of the bucket foundation breakwater is less than the static stability safety factor.But the dis-placement mode of the structure and the failure mode of the soil foundation in the dy-namic stability analysis agreed with the results in static stability analysis.And it was ob-tained that the displacement mode of this structure was rotational of the bucket founda-tion breakwater around a point below the bucket bottom.Besides,the results also show＆amp;nbsp;that plastic shear strain zones were running through the bucket bottom to ground in both the sea and land sides.And the active failure zone of the soil foundation was formed in the sea side while the passive failure zone was formed in the land side.The present re-search could be a reference for the design and application of the structure.