Effects Of Soft Layer In A Site On Earthquake Ground Motion

Ground that contains soft soil layer is a kind of common topography, a large number of seismic hazard and observations show that soft soil layer existint in soil layer structure has significant effect on gorund seismic response. Researching the effect of soft soil layer on ground response has significant sense for design of building earthquake prevention.Kelvin-Voigt model is used here to simulate viscoelasticity of soil and equivalent linear approximation is used to analyze ground response. The ground response is calculated when the soft soil layer has different depth or thickness by selecting three earthquake waves as input earthquake waves and useing four kinds of ground soil structure. At last, calculation result is analyzed, and then the effect rule of soft soil layer on ground earthquake response is gained.The results show that the response spectra feature period of ground containing soft soil layer increases and peak value of response spectra decreases when thickness of soft soil layer increases; the response spectra feature period of ground containing soft soil layer increases and peak value of response spectra decreases when depth of soft soil layer increases.Futhermore, when thickness and depth of soft soil layer are smaller, peak value of response spectra is larger than the value of ground without soft soil layer, and when thickness or depth of soft soil layer are larger, peak value of response spectra is smaller than the value of ground without soft soil layer.