Research On The Design Method Of Underpinning Structure For Jacking And Rectification Based On Stiffness

In general,the building rectifying technology can be divided into crash-landing method and jacking method.With the development of jacking equipment and control system,the jacking rectifying method has been applied more and more widely.The design of underpinning structure is one of the keys in the whole jacking rectification of buildings.Underpinning structure bears the load of the superstructure on the one hand,and coordinates with the stiffness and deformation of the superstructure under the non-uniform jacking displacement.For the study of jack-up rectifying inclination of underpinning structure affect the performance of structure overall stress and its relationship with the rigidity of the upper structure,the six layer frame structure of a typical jack-up rectifying inclination analysis,different stiffness of underpinning structure is studied in the process of jack-up structure overall stress,explores the upper structure and underpinning structure both the stiffness ratio of the influence of the structure,The conclusion is verified by an engineering example.Firstly,a typical frame structure was designed and the ABAQUS finite element model of the superstructure was established.The vertical stiffness of the frame structure was obtained by numerical simulation and compared with the vertical stiffness obtained by mechanical analysis.The results were close to each other.Then,the underpinning structure for tilt correction was designed for the frame structure,and the maximum jacking rate was 6‰ and 8‰,respectively,to obtain the stress of the overall structure under different stiffness underpinning structure parameters.It is found that the stress of the superstructure mainly concentrates on the bottom frame column.With the increase of the underpinning stiffness,the stress of the superstructure and underpinning structure decreases first and then increases,and the phenomenon of stress concentration appears.Through the analysis of the parameter variation of the height of the underpinning beam,it is found that when the ratio of the underpinning stiffness to the average stiffness of the superstructure is close,the overall force of the structure is the most reasonable.Finally,based on stiffness of underpinning structure design method is applied to a real jack-up remedy in lean project,underpinning node in accordance with the requirements for bearing capacity design,through the layer with the upper structure stiffness between the principle of equal to underpinning node design of coupling beam height,found the underpinning structure with the engineering practice of coupling beam height,The rationality and accuracy of the design method are verified by internal force analysis.