Research On Seismic Reduction And Isolation Measures For Urban Underground Station Structure

Urban underground structure is an important part of urban function.Urban underground structure has the characteristics of complex structural form,large spatial scale,difficult safety hazard and difficult repair.Due to the relatively late start of seismic research on underground structures in China,this has led to weaker aspects of seismic analysis methods and experimental studies of underground structures.Although China has promulgated the specifications for seismic design of underground structures and gradually improved the seismic design of underground structures,considering the importance of underground structures,the uncertainty of ground motions and the complexity of site soils,underground structures still face Quite a big risk.Therefore,research on shock absorption and isolation measures is also extremely necessary.This paper first introduces the seismic isolation measures and their principles,and gives the implementation methods of various seismic isolation measures to provide calculation parameters for subsequent numerical calculations.Then,the rationality of simplifying the three-dimensional station into a two-dimensional station is verified by numerical calculation;and several key problems in the numerical model are discussed,and a reasonable numerical analysis model modeling method is proposed.Subsequently,the numerical calculations are used to calculate and compare several seismic isolation and isolation schemes proposed in this paper.The effects of various seismic isolation and isolation measures and their advantages and disadvantages are discussed.Finally,in order to verify the rationality of numerical calculation,the corresponding shaking table test scheme is designed.Based on the calculation and comparative analysis of this paper,the following main conclusions can be drawn:(1)In terms of numerical calculation model,the spatial influence range of the station end wall is about 1.5 times of the lateral width of the structure,which is consistent with the proposed value of the specification;in this range,the calculation result of the two-dimensional model is slightly larger than the calculation result of the three-dimensional model.It can be seen that when designing based on the results of two-dimensional plane calculation,the structure is biased to safety,so simplifying the calculation of the three-dimensional station model into two-dimensional calculation is practically feasible in engineering.(2)Exploring the seismic isolation effects of four kinds of seismic isolation measures through numerical calculation: rigidly connected to the wall to reduce the isolation measures,try to choose the station with larger elastic modulus and smaller length of the ground connection wall to reduce the vibration isolation effect;Flexible isolation measures should choose a flexible isolation layer with small shear modulus and large thickness to achieve better isolation effect;For the material characteristics minus vibration isolation measures,the effect of reducing the vibration isolation by changing the parameters of the structural materials is not significant;For the structural characteristics of the seismic isolation measures,the sliding bearing as the seismic isolation measures of the underground station structure has obvious effects on reducing structural deformation and stress.