Uncertainty Of Dynamic Nonlinear Parameters Of Clay In Xiong’an New District

Located in the hinterland of Beijing,Tianjin and Baoding,the establishment of the Xiong’an New District is an important decision made to further build a high-quality engine for the coordinated development of the Beijing-Tianjin-Hebei region.Xiong’an New District is adjacent to the Tanlu Seismic Zone,which has experienced many destructive earthquakes.Therefore,in the construction and planning of Xiong’an New District,it is very important to ensure the seismic safety of building structures in the area.Site seismic response analysis is one of the most critical parts of structural seismic design,and the variability of soil dynamic nonlinear parameters has a significant impact on site seismic response analysis results.The soil mass has strong spatial variability,and the regional difference has obvious influence on the dynamic nonlinear parameters of the soil mass.Moreover,there is no systematic study on the uncertainty of the dynamic parameters of the soil mass in Xiong’an New District.Therefore,it is of great engineering application value to study the uncertainty of dynamic nonlinear parameters of clay in Xiong’an New District.Therefore,this paper takes the viscous soil in Xiong’an New District as the research object,studies the variability of dynamic nonlinear parameters of soil under different buried depths,gives the reference value range of soil property parameters under typical strains under different probability levels,and studies the influence law of the variability of dynamic shear modulus ratio and damping ratio on ground motion parameters.The work and the results are as follows:1.This paper briefly introduces the regional seismic environment and geomorphic features of Xiong’an New District,and expounds the site conditions of Xiong’an New District from the topography,hydrology and groundwater,soil layer structure,soil physical and mechanical characteristics.2.The study on the uncertainty of dynamic nonlinear parameters of clay in Xiong’an New District under different buried depths shows that the variability of dynamic nonlinear parameters decreases with the increase of buried depth.Under the same burial depth,the variability of dynamic shear modulus ratio increases with the increase of shear strain,and the damping ratio variability increases first and then decreases with the increase of shear strain,reaching the peak value at the sensitive value of 10^-4.The reference ranges of dynamic nonlinear parameters of the Xiong’an New District are given under different probability levels.The reference range of dynamic shear modulus ratio decreases with the increase of the buried depth,while the reference range of damping ratio has no obvious rule with the buried depth.Both of them increased with the increase of probability level,and showed a trend of first increasing and then decreasing with the increase of shear strain.3.The seismic response analysis of soil layer was carried out on the soil dynamic nonlinear parameters in different buried depths under different probability levels,and the influence law and quantification results of dynamic shear modulus ratio and damping ratio with probabilistic significance were obtained.With the decrease of probability level,the influence of parameter variability on acceleration response spectrum gradually decreases.Compared with damping ratio,dynamic shear modulus ratio variability has more significant influence on seismic response of soil layer.The acceleration response spectrum has the maximum value when the probability level is 100%.The research results of this paper can be applied to the seismic design of engineering based on probability and reliability,and also provide a reliable basis for the determination of ground motion parameters in this area.