![]() However, in the meantime, numerical studies predicted a stress concentration at the interchange conjunction due to the stiffness change. ![]() Thanks to the existence of the conjunction sidewall, a lower bending moment was found in the column of the interchange station, compared with the single station. Such influence may be more notable in a certain region close to the conjunction. Compared to the single station with a uniform cross-section, the seismic response of the cross interchange station is affected by the interchange conjunction, which brings abrupt stiffness and a change of structure. Recent studies about the seismic response of cross interchange stations were mainly based on full-time numerical simulations, while fewer proposed simplified pseudo-static analyses based on plate theory. In the specific case of cross interchange stations, its seismic response has not been studied extensively thus far. The above methods are mostly applied to the analysis of tunnels and underground structures with uniform cross-sections. To summarize, in all of the above analysis methods, experimental modeling has been a key factor for calibrating and validating the models and to provide evidence on the mechanisms and factors affecting the response. The numerical results were found to often not be satisfactory for predicting permanent changes in the internal force of a structure and rather dispersed, especially when high yielding was involved during strong shaking. In fact, a recent study presented several sets of numerically predicted results to a set of centrifuge campaigns of tunnels in sand subjected to earthquake loading. However, the above preconditions are not explicit if found without validation after the laboratory or field observation of the dynamic behavior of the underground structure. Arguably, the last category of methods, numerical full-time analysis, is considered as the most accurate method for the seismic analysis of underground structures, provided that some of the most important aspects (e.g., soil nonlinearity, relative soil–structure stiffness and soil–structure interface) can be modeled appropriately. #Interchange mini metro full#The simplified pseudo-static analyses can underestimate or overestimate the full dynamic results with a difference of 20–40%. The accuracy of the second kind of analysis is evaluated by comparing it to the numerical dynamic analysis and experimental study. The application of the first kind of solution is limited by the assumptions of linear elastic soil response (with the exception of ) and soil–structure interface behavior. There are various analysis studies available in the literature, ranging from closed-form solutions to simplified pseudo-static analyses and numerical full dynamic modeling. Īiming to shed light on the seismic response and facilitate the design methods of underground structures, extensive research has been carried out. However, the seismic resistance of such structures may be affected by the abrupt change of stiffness at the interchange conjunction, which may generate stress concentrations. As a relatively modern development, cross interchange stations have not yet been tested by a major earthquake. The collapse of the Daikai Station in Kobe, Japan during the 1995 Hyogoken-Nambu earthquake and the failure of the Bolu highway tunnel during the 1999 Duzce earthquake in Turkey, along with the damage and collapse of the Longxi tunnel during the 2008 Wenchuan earthquake in Sichuan, China, provide evidence that underground structures could be vulnerable to earthquakes. Understanding the seismic impact on such complicated underground structures and developing a rational design method is therefore of critical importance. Insights on the seismic response of the interchange station are provided.Ĭross interchange stations constitute essential components of the metro system, and the expanding metro grids in modern cities lead to the growing demand of their construction. The concentration of the longitudinal strain was observed near the conjunction. The bending strains of the columns measured in the interchange station were found to be smaller than those in the single station. Test data recorded by accelerometers and strain gauges are presented. Parallel tests of a single two-story station were correspondingly carried out as a contrast. ![]() The seismic motion was input along the transversal direction of the two-story structure, including white noise and sinusoidal seismic excitations. Synthetic model soil (a mixture of sand and sawdust) and granular concrete with galvanized steel wires were used to model the soil–structure system. The interchange station was composed of a two-story section rigidly connected to a perpendicular three-story section, leading to an abrupt change of stiffness in the conjunction area. ![]() #Interchange mini metro series#Regarding the seismic performance, a series of large-scale shaking table tests were performed on an interchange station. Interchange is essential in a metro network. ![]()
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