Uncertainty analysis of seismic response of soil layer in deep overburden area

Taking Shanghai area as the representative of deep overburden area, based on abundant geological data, this paper comprehensively and systematically analyzes the possible distribution range of 5 uncertain factors, including soil layer distribution, shear wave velocity, soil dynamic characteristic parameters, density and seismic input interface, in a depth of 100 m, and uses the logic tree analysis method and equivalent linear method for seismic response analysis of soil layers, the surface peak acceleration and response spectrum results of 5 uncertain factors, 3 exceedance probabilities and 4 typical geological holes under 23 working conditions are calculated. It shows that the parameters of soil dynamic characteristics, shear wave velocity, soil layer distribution and density in the depth of 100 m are low sensitive parameters, and their uncertainty have little impact on the ground motion parameters, the difference of peak acceleration are basically within 5%. The seismic input interface is a highly sensitive parameter, which has a great impact on the ground motion parameters (especially to the low frequency band), with the maximum difference of 30%—40%. The seismic input interface should be reasonably set in the seismic safety evaluation to avoid the adverse impact on the seismic fortification parameters of the project.