Study On Subway-induced Environmental Vibration And Isolation Method Of Building From It

With the department of metropolitans, environmental vibration and noise is getting worse and notable, witch have been distributed to the first of the seven social calamities in Japan. Subway is a way of rapidness, punctuality and mass conveyance, etc. Its development is faster and faster than other traffics in Beijing, Shanghai, etc. Therefore, the effect of environmental vibration from subway will be more and more prominent.This paper is based on the study of the vibration isolation method of the test theater, the rehearsal center, and the teaching building in Shanghai Music College from the impact of Subway Line No. 1 and No. 10. At first, the theory and analyzing method about environment vibration is summed up. On the based of vibration tests data from the site ground near the Subway Line No. 1, the suitable load serials on tunnel invert for the simple and complex model are presented. Then, by using a two-dimension model the influencing factor of finite element method on environmental vibration is analyzed. Difference between three-dimension models and two-dimension models is analyzed, and the analyzing method suited to two-dimension methods is presented. Moreover, combined with the instance of building, the finite element method for calculating building vibration from subway and its influencing factor is analyzed. Finally, the effect of vibration isolation of several types of barriers in free field is researched, and the floating slab in buildings for vibration isolation and the base isolation method of buildings is researched. The main research production is as follow:1. Theory of finite element and 2.5 dimension finite element methods for analyzing vibration from environmental vibration is summarized. Some aspects on analyzing in the two methods are also summarized. The computing method of processing and evaluating of vibration data is analyzed. The common attenuation law and theory about vibration wave is summed up.2. By analysis of the vibration tests data from the site ground near the Subway Line No. 1 in Shanghai, the characteristics of environmental vibration from subway trains and those from autos are distinguished. By considering the Hertz nonlinear contact and track irregularity, the load series on rail is obtained using the acceleration test data on rail from other researchers and different vehicle models. Then, utilizing the simple and complex models, the load series on tunnel invert suited to different analyzing model of environmental vibration from subway is researched.3. Utilizing the plane model, the applicability of the modal superposition method and the direct integration method for finite element method on environmental vibration calculation is analyzed. Moreover, rationality of Rayleigh damping coefficient selecting is discussed, and determination of the scope of analyzing model, element size and time step is studied. The several artificial boundary conditions are compared about their effect on vibration calculation.4. Working out the program of 2.5 D finite element method, witch is solved with plane finite element but solving three-dimension questions. By three-dimension and 2.5 D finite element method, separately, considering the moving of vehicle and longitudinal transmitting of vibration, attenuation law of environmental vibration from subway in soil is obtained. Then it is compared with the conclusion from two-dimension model, and the feasibility of two-dimension method is discussed, in addition, the load on tunnel invert is obtained. Moreover, using two-dimension model, the vibration attenuation law of free field in thick-layered soft soil is analyzed, and the soil scopes requiring consider by various limit criterions is obtained for building.5. Using the interactive model of buildings and soil, the influence on vibration level in free field soil with or without the building and with different building arrangement is discussed. Then, the suitable input series on the building support is analyzed. Combined with the analysis of vibration from the impact of subway about the teaching building in Shanghai Music College, the transmission law of vibration in buildings and the calculating method of it are analyzed. The different meshing criteria of building model with between shear wave length and bending wave length are discussed. Then, various methods of base input for the single-support excitation and multiple-support excitation in building vibration analysis is discussed about their influence on vibration level results, and the large mass method in multiple-support excitation is analyzed, which is suitable to large layout buildings, so the attenuation law in such building is obtained. It is also compared that the difference between three-dimension and two-dimension model of building in vibration analysis.6. Utilizing the two-dimension model, the effect of vibration isolation barriers including concrete filled trenches, open trenches and WIB (wave impeding barriers) under a building is analyzed. Combined with the analysis of vibration isolation from the impact of subway about the test theater and the rehearsal center in Shanghai Music College, the isolation effect of floating slab in the room of the rehearsal center is discussed, especially on the interactive between floating slab and the building slab under it and the determination of the input time series for single-support analysis of the floating slab. Moreover, the effect of the base-isolation by springs under the test theater auditorium hall is analyzed and the vibration characteristic of such building is discussed.