| Structure-foundation dynamic interaction analysis is a research hotspot in hydraulic engineering,nuclear power and other fields.With the gradual deepening of research,the study of interaction methods and models tends to be refined.In addition to the influence of research methods,the fine simulation of complex site characteristics has an important influence on structural response.At present,the research of foundation model mainly focuses on the fine description of the near-field foundation.Different from the near-field morphological characteristics of the free,such as uneven surface,foundation pit excavation,artificial replacement and foundation treatment,will cause wave scattering and diffraction,which will have an important impact on the structural dynamic response.Due to the complexity of modeling and subdivision of uneven sites,the simplified model is usually used in the traditional analysis process,or tetrahedral elements are used for subdivision in order to maintain the site characteristics,resulting in reduced accuracy of the solution.Therefore,it is urgent to find a method to analyze the dynamic interaction of complex sites.In the field of structure-foundation dynamic interaction,the establishment of refined models mainly has the following difficulties:modeling and meshing of uneven sites,selection of mechanical analysis models,connection of mesh models of foundation and structure,the simulation of infinite field of foundation,the appropriate solution platform and so on.In this paper,a complete dynamic interaction analysis method based on rapid modeling and automatic octree meshing is proposed,and the feasibility of this method is verified by numerical examples.The main research contents are as follows:(1)A fast modeling method based on Google map and CAD contour map is proposed to realize the transformation from map or drawing to 3D STL model.Besides,the method of automatic octree meshing suitable for STL model of uneven site is studied,and the subdivision process can be completed automatically only by setting control parameters.(2)By writing the calculation program,the transformation from the octree mesh model to the scaled boundary finite element polyhedral element model is realized.The topological structure information of the octree mesh model is analyzed,and the SBFEM element calculation model is constructed by extracting the information of nodes,elements,surfaces and similar centers and the problem of singular cells in the calculation model is solved.In addition,the spring-viscous boundary is set to simulate the infinite field of foundation,and the input file is calculated according to the information of boundary surfaces.Finally,the rationality of ground motion input and the correctness of the program are verified by analyzing the calculation results of cantilever beam,free field and uneven site.(3)The interface between dam and the foundation is selected,and special elements of the foundation interface is established.Then,the combination of finite element dam and scaled boundary finite element foundation is completed by using the surface-to-surface contact method in ABAQUS.Based on the realization of SBFEM elements by user element subroutine of UEL,the analysis of structure-foundation dynamic interaction is completed on ABAQUS platform,and the response visualization of SBFEM model is completed through post-processing.(4)The dynamic interaction analysis of a practical engineering example verifies the correctness of the dam and foundation combination method,and shows the feasibility of the whole research method.Based on the dynamic interaction analysis of simplified foundation and uneven site,the influence of site characteristics on dynamic response of structure is studied.The results show that the uneven site model increases the stress and acceleration response of the structure,and causes the increase of the peak displacement parallel with river-direction and the change of the extreme point position. |
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