Seismic Research of Nanning Subway Tunnel Section Crossing Silty Sand

Abstract

After the Kobe earthquake, the seismic design of underground structures has been widely valued. Guangxi Nanning Metro passes through a saturated silt fine sand layer, while considering Nanning seismic fortification intensity, different geological conditions and underground structure forms of Nanning Metro are compared and analyzed using different seismic design methods, and combining the characteristics of the actual engineering structure, one-dimensional free-field analysis method, response displacement method and three-dimensional equivalent linear time history analysis method are used to analyze and study soil response and structural response. The results show that: (1) The relative displacement of the structure calculated by the three-dimensional equivalent linear time history analysis method is consistent with the results of the one-dimensional free-site analysis method, and both decrease with the increase of the depth. (2) For the relative displacement changes on the lining structure, when the three-dimensional equivalent linear time history analysis method is used, the maximum relative displacement occurs on the upper part of the lining structure, which is 523.43 mm; when the reaction displacement method is used, the maximum relative displacement occurs At the lower right side of the lining structure, it is 63.89 mm. The calculation result of the three-dimensional equivalent linearization time history method is obviously greater than that of the reaction displacement method.