Underground Structure Based On Thin Plate And Deformation Synergy Theory

With the advancement of urbanization in China,the contradiction between the spatial demand of urban development and limited land resources has become increasingly prominent.In the process of urban construction,the rational use of underground space as an effective means to alleviate this contradiction is widely used.However,with the increase of underground structure engineering practice,anti-floating failure accidents of underground structures occur from time to time.Anti-floating failure has become a key problem to be solved urgently in underground structure engineering.There are various reasons for the anti-floating failure of underground structures.Among them,the factors in engineering design are excessive simplification of calculation model,inconsistent anti-floating calculation formulas for underground structures in codes and standards,and unreasonable anti-floating design principles.These factors will lead to the design of the component can not meet the requirements of the actual water buoyancy,which will cause the destruction of the underground structure,resulting in economic losses and safety problems.Aiming at the problem of stress and deformation of underground structure under the action of water buoyancy,this paper establishes a mechanical calculation model based on the theory of thin plate and cooperative deformation,determines the relevant parameters and boundary conditions in the model,and analyzes the internal force distribution and deformation law of each component of underground structure under the action of water buoyancy through the calculation model.The main research contents of this paper are as follows :(1)Based on the three-force dynamic equilibrium mode of the underground structure under the action of water buoyancy,that is,the water buoyancy perpendicular to the bottom plate surface,the gravity of the structure,and the dynamic balance between the foundation reaction force,considering the influence of the foundation reaction force on the stress and deformation of the underground structure floor,the mechanical calculation model of the underground structure floor is established in stages with the disappearance of the foundation reaction force as the threshold.(2)Considering the influence of the shape and boundary conditions of the bottom plate of the underground structure on the calculation results of its internal force and deformation,different calculation methods are proposed : 1)For the rectangular bottom plate,the double triangular series solution method is improved by combining the constraint conditions,which avoids solving the infinite series;2)For the nonrectangular floor,the approximate solution is based on the energy variational principle.Through specific examples,the correctness of the two calculation methods is verified by numerical simulation.(3)According to the deformation compatibility conditions between the components of the underground structure under the action of water buoyancy,the mechanical calculation model of frame beam,frame column and roof is established,and the internal force and deformation response of beam,column and roof caused by floor deformation are obtained.Based on the calculation model of the component and the actual anti-floating failure engineering case,the internal force distribution and failure mode of each component of the underground structure under different water levels are studied.Finally,the correctness of the calculation model proposed in this paper is verified by comparing the calculation model,the inverted floor calculation model and the failure characteristics of the anti-floating failure engineering site components.