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在北京工业大学九子振动台台阵系统上开展了一系列锯末混合土场地模型试验,试验中模型箱采用装配式连续体刚性模型箱,其尺寸为7.7 m(长)×3.2 m(宽)×1.2 m(高),输入地震动时程采用El Centro地震动记录和天津地震动记录,地震动输入方向为水平横向和水平纵向。通过场地模型振动台试验,验证了设计的模型箱的较小的“边界效应”影响程度,同时考察了锯末混合土场地模型的动力特性及其变化规律。对部分试验结果,包括场地反应的地震动峰值加速度及其动力放大系数、加速度时程及其频谱,进行了具体分析。试验结果表明:本次使用的装配式连续体刚性模型箱边界效应处理效果良好,同一水平面上不同部位土体反应的加速度仅有较小差异;随着地震动输入强度的增大,同一测点反应的峰值加速度总体上在增大,但其加速度动力放大系数总体上呈现减小的趋势,反应的频谱组成从较高频率向较低频率移动。这些结果说明,随着地震动输入强度的增大,土体由于刚度发生变化而相对变软,土体模量逐渐降低。
A series of field tests on sawdust mixed soil were carried out on the 9th vibrating table array system of Beijing University of Technology. The model box was assembled with a continuous rigid box model and its dimensions were 7.7 m (length) × 3.2 m (width) × 1.2 m (high). The earthquakes recorded in El Centro and the earthquakes recorded in Tianjin are recorded in the input earthquakes. The direction of earthquakes is horizontal and horizontal. Through the shaking table test of the site model, the effect of the smaller “boundary effect” of the designed model box is verified. At the same time, the dynamic characteristics and the variation regularity of the model of sawdust mixed soil are studied. Part of the experimental results, including the peak ground motions of ground motions and their dynamic amplification factors, acceleration time histories and their spectra, are analyzed in detail. The experimental results show that the boundary effect of fabricated rigid box model has good effect, and there is only a small difference in the acceleration of soil response in different parts of the same horizontal plane. With the input intensity of ground motion increasing, the same measuring point The peak acceleration of the reaction generally increases, but its acceleration power amplification coefficient generally shows a decreasing trend, and the spectral composition of the reaction moves from a higher frequency to a lower frequency. These results show that as the input intensity of ground motion increases, the soil becomes relatively soft due to the change of stiffness, and the soil modulus decreases gradually.