Amplification Of SHWaves By Group Cavities In A Layered Half-Space

To release traffic pressure of the city, some major cities in China build subwaysystem in the downtown area, most of which are large group cavities made up of twocavities. The construction of those cavities will inevitably influence the earthquakedesign of the surrounding area and quantitative estimation on the influence plays animportantroleinthesafetyevaluationforearthquakeofthepresentbuildings.However,in the former research natural soil was simplified into sotropy elastic solid medium foranalysis. But since natural soil has different depositional ages, we need to use layeredmedia to reflect the heterogeneity along with depth. On this background, this thesisstudiestheamplificationofSHwavebygroupcavitiesinlayeredspaces.Using the indirect boundary-element method, the paper studies and discussed theamplification of SH waves by double caverns in a single layer soil on the bedrock. Itpicks and discusses one kind of double-cavern site with representative thickness, andtalksaboutthreedifferentstiffnessandapertureration.From amplification effect curve we know that the amplification of SH waves willbe influences greatlyby such parameters as aperture ration, stiffness rate of bedrock andsoil layer and dimensionless frequency. From the amplification spectrum we can seethat for SH wave, every dot in the canyon surface has a series of incident frequencywhich makes the resonance phenomenon. Amplitude of displacement on the surface on theresonance frequency grows with the stiffness. And the thickness of the layer influencesdirectly the location of the resonant frequency which increases along with stiffnessration of the rock and soil. Usingthe indirectboundaryelementmethod this paper discussesthe differences and reasons of the amplification effects of the incident surface elasticwave bysingle-phrase layered half space and even half space cavern, and points out thenecessity and reasonableness of the research by the layered model. Using the indirectboundaryelementmethod solves theScatteringofincident elasticwavebylayered saturatedsitecavern.