Seismic mitigation effects of split columns in underground station structures

It has been shown that the lack of horizontal deformation capacity of the middle columns under high axial pressure is the key factor leading to seismic failure of shallow frame underground structures. When the bearing capacity of the split columns is equal to that of the whole columns, the split columns have better deformation and energy dissipation capacity. Based on ABAQUS finite element numerical analysis, by establishing a three-dimensional numerical model for soils and underground structures as a whole, the Pushover analysis method and the dynamic time history analysis method are used to compare and study the dynamic response differences between the new underground station structure and the prototype station structure. The research results show that the seismic response of the story displacement of the new underground station structure with split columns increases, but the influence degree is not significant compared with the improvement of the deformation capacity of the columns. The replacement of the cast-in-place integral columns with the split columns will make the internal force of the structure section redistributed, the shear force borne by the middle columns greatly decreases, and the change of the shear force of the side walls is not obvious. On the whole, the new type of underground station structure with split columns can significantly improve the incoordination of deformation between the middle columns and the side walls under high axial compression ratio, and can effectively improve their seismic performance.