关键词: 振动台模型试验, 可液化场地, 三拱立柱式地铁地下车站结构, 地震损伤机制

Abstract: A series of large-scale shaking table experiments was conducted on three-arch type underground structure in liquefiable ground subjected to the near field earthquake and the far field earthquake. Experimental results are discussed in items of pore water pressure, earthquake-induced ground settlement, acceleration response of soil and structure and the deformation of model structure. The measured data substantiate that, the buildup of pore water pressure mainly experiences two stages, at the first stage, the pore water pressure increases slowly, at the second stage, the pore water pressure rises sharply. Good agreement is found between the development of pore water pressure and Arias intensity. A larger peak of Arias intensity corresponds a higher peak of pore water pressure ratio. The distribution of pore water pressure field implies a lower degree of liquefaction at the bottom of model structure as result of a low intensity earthquake; while for the high intensity earthquake, the lower degree of liquefaction occurs at the bottom of ground. Subjected to the high intensity earthquake, the model structure generates an upward movement relative to the foundation. Both model structure and model soil present intense response to the ground motion with low frequency, the peak acceleration of ground motion in shallower fine sand layer shows some ‘spikes’ during the shallower liquefied soil cyclic mobility. Moreover, the low frequency components appear more at the upper soil than deeper soil. For the structure, the strain response of center column is larger than that of subarch, and the strain recorded at atrium arch is the smallest. With the increase of tensile strain amplitude, the natural frequency of the model structure decreases. The tensile strain recorded at the primary observation plane is distinctly different from that at secondary observation plane, implying that remarkable spatial effects of model structure.

Key words: shaking table model test, liquefiable ground, three-arch type underground subway station structure, seismic action