考虑接触面影响的地下结构地震响应研究

Research on Seismic Responses of Underground Structures Considering Influence of Contact Surfaces

针对可液化地层地下结构在地震作用期间和地震后的动力响应开展水土耦合有限元分析。计算采用基于有效应力的水土完全耦合有限单元-有限差分方法,嵌入能够准确反映土在循环交变荷载作用下动力行为的CM模型描述土体的交变移动特性,采用考虑结构体积效应的弹性梁和柱组合单元进行结构建模,并且设定土-结构界面节理单元;对比分析了在罕遇地震中土体的加速度响应、超静孔隙水压发展状况,地下结构的内力和震后地层固结沉降趋势。结果表明:地下结构在震后一定期间继续上浮,震后的位移发展明显大于地震期间位移发展,且待超静孔隙水压完全消散后,结构表现为整体沉降。

A water-soil coupling finite element analysis for the dynamic response of underground structure in the liquefiable site during and after earthquakes was performed. In the calculation, the water-soil fully coupled finite element-finite difference method based on the effective stress theory and the CM model(the Cyclic Mobility model) accurately reflected the dynamic characterisitcs of soil under cyclic loads were adopted. Considering the structural volume effect, the hybrid elements composed of elastic beams and columns were used to construct the model of the station structure, and the joint elements at soil-structure interfaces were set. The acceleration response of soil during a rare earthquake, the development of excess pore water pressure, the internal force of the underground structure and the consolidation settlement after the earthquake were simulated and analyzed. The results showed that the underground structure continued to float up after the earthquake, and the displacement development after the earthquake was significantly greater than that during the earthquake. When the excess pore pressure almost completely dissipated, the structure settlement tended to be stable.