基于统计特征的软土场地地震动模拟技术研究

发布时间：2018-10-18 13:09

【摘要】：地震动模拟技术对于地震安全性评价、结构动力时程分析和抗震设计等工作有着非常重要的作用。目前软土场地地震动模拟通常分两步得到,首先通过衰减关系确定基岩地震动,然后通过场地计算模型得到软土场地地震动。但衰减关系一般是由地表地震动统计确定,且软土场地的场地反应复杂,场地计算模型也具有较大不确定性。本文以实际地震动为数据基础,对软土场地地震动工程特性参数进行了统计分析,对Rezaeian模型在软土场地地震动模拟中的应用进行了适当探讨和改进,利用参数回归结果模拟地震动并进行了验证。本文主要工作和结论如下:(1)收集整理了软土和其附近基岩场地地震动,从地震动三要素、强度包线和频率非平稳特性三个方面,确定了定量描述地震动特性的工程特征参数,并研究了其与矩震级和断层距的回归关系,对软土和基岩地震动工程特征参数的回归结果进行了对比分析。(2)以Rezaeian模型离散化的地震动模拟公式为理论基础,讨论了其在软土场地地震动模拟中的优越性。根据对功率谱模型的比较,选择绝对加速度脉冲响应函数作为模型脉冲响应函数。(3)通过由HHT方法得到的瞬时卓越频率,探讨了模型频率参数的识别。当模型脉冲响应函数参数固定时,对模拟随机过程的瞬时卓越频率取自然对数后的统计发现,其近似服从正态分布,其标准差与脉冲响应函数的阻尼比近似线性相关。对地震动的瞬时卓越频率取自然对数后进行线性拟合以识别模型主导频率参数,用拟合的残差标准差识别模型阻尼比参数。(4)对软土场地地震动识别的模型参数进行统计回归,进一步利用参数回归结果模拟地震动;并分别与两条实际地震动和NGA模型BA08进行比较,对模拟结果进行了验证。
[Abstract]:Ground motion simulation plays an important role in seismic safety assessment, structural dynamic time history analysis and seismic design. At present, the ground motion simulation of soft soil is usually divided into two steps. Firstly, the ground motion of bedrock is determined by attenuation relation, and then the ground motion of soft soil is obtained by site calculation model. However, the attenuation relationship is generally determined by the ground motion statistics, and the site response of the soft soil site is complex, and the site calculation model is also uncertain. Based on the actual ground motion, this paper makes a statistical analysis on the engineering characteristic parameters of the soft soil ground motion, and discusses and improves the application of Rezaeian model in the soft soil ground motion simulation. The results of parameter regression are used to simulate the ground motion. The main work and conclusions of this paper are as follows: (1) the ground motion of soft soil and its surrounding bedrock site is collected and sorted out. From the three aspects of ground motion three elements, intensity envelope and frequency non-stationary characteristics, the engineering characteristic parameters for quantitatively describing the ground motion characteristics are determined. The regression relationship among moment magnitude and fault distance is studied, and the regression results of engineering characteristic parameters of soft soil and bedrock ground motion are compared and analyzed. (2) based on the discrete ground motion simulation formula of Rezaeian model, Its superiority in the simulation of ground motion in soft soil is discussed. According to the comparison of the power spectrum model, the impulse response function of absolute acceleration is selected as the impulse response function of the model. (3) the identification of the model frequency parameters is discussed through the instantaneous excellent frequency obtained from the HHT method. When the parameters of the model impulse response function are fixed, it is found that the instantaneous excellent frequency of the simulation random process is approximately obeyed from the normal distribution, and its standard deviation is approximately linearly related to the damping ratio of the impulse response function. In order to identify the dominant frequency parameters of the model, the instantaneous excellent frequency of ground motion is linear fitted with natural logarithm, and the damping ratio parameter of the model is identified by the fitted residual standard deviation. (4) the model parameters of ground motion identification in soft soil are statistically regressed. The simulation results are compared with two real ground motions and NGA model BA08, respectively, and the simulation results are verified.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU447;TU435

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