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Research On Mechanical Properties Of Pile-slab Subgrade Structure Of Ultra-long Continuous Highway

Posted on:2021-05-28Degree:MasterType:Thesis
Country:ChinaCandidate:J T WangFull Text:PDF
GTID:2392330614459778Subject:Bridge and tunnel project
Abstract/Summary:PDF Full Text Request
In recent years,the pile-slab subgrade structure has gradually been applied to the field of highway construction in China,but there are few theoretical studies on pile-slab subgrade at home and abroad,and there are no relevant design specifications,which brings great difficulties to the large-scale application of pile-slab subgrade.Pile-slab subgrade is a new type of subgrade structure,which is mainly composed of pile foundation,beam slab and pile-slab joint.Compared with the traditional subgrade,it has the advantages of small post construction settlement and large overall stiffness.Because of the innovation of the structural system and its key structures,such as pile-slab connection structure and joint connection structure,the mechanical properties of pile-slab subgrade structure are different from that of conventional bridges and ordinary subgrade.It is necessary to study the mechanical properties of the new structure system and its key structures to ensure its safety and durability,so as to realize its large-scale application.In this paper,the pile-slab subgrade of the reconstruction and expansion project of the Lintou-Longxi Interchange Section of G5011 Wuhu-Hefei highway in Anhui Province is taken as the supporting project and research object.Firstly,the whole finite element model of pile-slab subgrade structure system is established.Then,the refined nonlinear finite element models of pile-slab connection structure and joint connection structure are established.Finally,according to the whole model of subgrade and the refined model of key structures,the mechanical properties of pile-slab subgrade are studied in depth.The main research contents and conclusions are as follows:(1)According to the structural characteristics of pile-slab subgrade,the overall finite element model of pile-slab subgrade structure system is established,and the influence of lane load and vehicle load on the mechanical performance of this kind of structure under the combination of basic combination and short-term effect is clarified,It is determined that the pile-slab subgrade structure can well meet the requirements of bearing capacity and normal use.Then,by analyzing the structural dynamic characteristics of the pile-slab subgrade,we can see that the overall stiffness of this kind of structure is large,especially the longitudinal and vertical stiffness,but the transverse stiffness of the plate beam is relatively small,and the overall torsional capacity of the structure is lower than the bending capacity.(2)The refined nonlinear finite element model of pile-slab connection structure is established,and the stress of flange plate,bolt,stiffener ring and bolt head in pile-slab connection structure is analyzed by using the theory of compression bending column.It is known that the size parameters of flange plate and bolt adopted by each pile meet the performance requirements of bearing capacity limit state and normal service limit state.In addition,the mechanical performance of the pile-slab connection structure can be effectively improved by setting the reinforced ring and bolt head.The role of the reinforced ring is more reflected in the pull-out resistance of the steel sleeve,and the bolt head can strengthen the anchoring ability of the grouting material in the steel sleeve.(3)By checking the mechanical properties of the lower bracket section,it is clear that the bracket section can meet the requirements of the mechanical properties.At the same time,the refined finite element model of the interaction between the new vertical limit expansion joint and the corbel is established.Through the analysis,it can be seen that although the cooperative work between the new vertical limit expansion joint and the corbel has limited improvement on the vertical stress of the corbel,it can effectively limit the vertical displacement of the end of the joint,and the stress level of the expansion joint is not large,but the tension of the reinforcement in the corbel is relatively high big.Moreover,the transverse stress of the lower bracket concrete can be effectively reduced by adding beam and reinforcement to the lower bracket,which further ensures the safety and durability of the bracket.
Keywords/Search Tags:Pile-slab subgrade, Multiscale simulation, Nonlinear finite element, pile-slab connection structure, Joint connection structure
PDF Full Text Request
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