地下结构抗震分析中若干土层模拟方法对比研究

动力时程在地下结构抗震分析中应用广泛,土体动力特性的准确模拟对动力时程分析结果有重要影响。介绍了Rayleigh阻尼和Hardin-Drnevich模型的基本理论,验证了等位移边界条件的有效性。从地表加速度响应和加速度幅值沿深度放大两方面,对比分析Mohr coulomb模型、Shake91、Rayleigh阻尼和Hardin-Drnevich模型在2Hz和8Hz正弦波作用下的响应结果。结合理论分析得出:静力Mohr coulomb模型对动力时程分析适用性有限;建议在地下结构抗震分析中采用场地基频与接近地震波主频固有频率计算Rayleigh阻尼参数;Hardin-Drnevich等粘弹性非线性模型比等效线性化方法更适用于地下结构抗震分析。

Comparative Study on Several Soil Ground Simulation Schemesin Seismic Analysis of Underground Structures

Time history analysis is widely applied in seismic analysis of underground structures, and the simulation of soil ground under dynamic loads has a significant influence on the result. Formulations of Rayleigh damping and Hardin-Drnevich model are introduced in the paper. The repeatable boundary condition is validated through comparison with far free boundary. On the basis of the repeatable boundary condition, the numerical simulation results with Shake91 model, Rayleigh damping model, Mohr coulomb model and Hardin-Drnevich model under 2 Hz and 8 Hz sine waves are compared from two aspects, that is, the ground surface acceleration responses and the peak acceleration profiles along depth. It is concluded that the Mohr coulomb model has limited applicability in dynamic time history analysis due to its constitutive model theory. It is recommended that the Rayleigh damping parameters be calculated with the fundamental frequency of soil ground and the natural frequency that approaching the dominant frequency of the imposed seismic wave. The viscoelastic model (e.g. Hardin-Drnevich model) is more suitable for seismic analysis of underground structures than the equivalent linear method, namely Shake91 model and Rayleigh damping model.