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Interchange mini metro10/30/2022 ![]() ![]() It could be a benchmark test of segmental tunnels in dry sand ground by means of 1 g shaking table.Īs revealed by the collapse of the Daikai Metro station during the 1995 Kobe earthquake, underground structures are not immune to seismic loading. ![]() The minutiae of the test are clarified to reduce uncertainties, and experimental results are carefully verified. Comprehensive results, including the acceleration responses of the two models, deformations at radial joints and in the diametral directions of the tunnel, bolt tensions between segments as well as strains of segments, are presented. Two white noise cases before and after the design-level cases are also performed to verify the dynamic characteristics of the models. Two levels of intensity and three typical central frequencies of idealized Ricker wavelets, making six cases of excitations, are applied to both the free-field model and the soil-tunnel model. #Interchange mini metro full#The properties of sand, the materials and design of the segmental tunnel, the construction process of testing models and the instrumentation scheme are introduced in full detail. The adverse effect of near-field ground motion on shield tunnel in soft soil site is significantly greater than that of far-field ground motion.Ī 1 g shaking table test of a shallow segmental mini-tunnel in sand is performed to investigate its dynamic responses. The near-field ground motion significantly stimulates the response of the tunnel structure in a wider low frequency range. The findings show that compared with far-field ground motion, the acceleration response of segmental lining, cross-sectional deformation, extension/closure of longitudinal joints, dynamic normal earth pressure, and strain on segmental lining are increased obviously under the action of near-field ground motion. The difference of seismic response of shield tunnel under near field ground and far field ground motion is compared and analyzed. A refined tunnel lining is developed to capture the extension/closure response of joints. #Interchange mini metro series#In order to study seismic performance of shield tunnel under near-field ground motion, a series of large-scale shaking table tests are conducted. The near-field ground motion is one of the challenges to underground structure in soft soil site. The presented results lead to a better understanding of the dynamic response of typical two-storey to three-storey cross interchange stations in soft soil. A series of numerical R′-F′ relations of the interchange station is concluded and compared to the R-F relation of a single station, along with the existing literature. The soil yielding, the soil-structure interface characteristics, and the soil-structure relative stiffness significantly affected the storey-drifts, the soil dynamic earth pressure, and the soil shear stress developed around the structure during shaking. The numerical analysis indicates combined racking-rocking deformation patterns for the cross interchange station, while the racking deformation is more-or-less evenly distributed among the three storeys away from the conjunction but highly concentrated on the bottom storey close to it. The study summarizes the key findings, focusing on the deformed pattern, the storey drift ratios, the earth pressure, and soil shear stress around the structures. The input motion condition, the soil-station interface properties, inertia of the structure, and the soil-station relative stiffness are the factors addressed in the parametric study. This paper presents an experimental study and a numerical parametric study, aiming to derive insights about the seismic response characteristics of typical cross interchange stations in soft soil and the critical parameters influencing the above response. Insights on the seismic response of the interchange station are provided. 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. 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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