分层土-箱基-框架结构在爆破地震作用下的计算分析
Computational analysis of layered soil-box foundation-structure dynamic interaction under explosive earthquake waves
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摘要: 以野外大比例(1∶2)分层土–箱基–框架结构试验模型的爆破震动试验数据为基础,利用有限元软件ANSYS二次开发语言apdl二次开发,将多次透射公式(MTF)添加到软件中从而实现对无限域的模拟,进而利用整体动力有限元方法研究人工透射边界、箱基周围回填土属性、软弱夹层及地震波主频范围等参数对上部框架动力反应的影响。数值算例与试验结果对比表明:爆破震动作用下,考虑二阶透射边界的数值结果和试验结果吻合较好,能模拟结构的真实动力反应,而固定边界和固基假定的计算结果偏大;箱基埋置深度浅、下卧土层刚度较大时,箱基周围回填土属性对结构反应影响不大;场地土中的软弱夹层对上部结构起到隔振减震的作用;与高频爆破地震波相比,低频地震波所产生的结构加速度反应更大,对结构破坏作用更强;固基假定下的结构反应计算结果在一些特定情况下并不总偏安全。Abstract: Experimental researches on a large-scale(1:2) in-situ model test of layered soil-box foundation-structure system to study the dynamic interaction under explosive earthquake waves were carried out.By applying a secondary development to ANSYS with multi-transmitting boundary,the effects of artificial transmitting boundary(ATB),property of backfilled soil,the weak intercalation and main frequency range on superstructure were comprehensively investigated.Compared with the results of fixed soil boundary and fixed base boundary,the results of ATB agreed well with the test results.Stiffness variation of backfilled soil played a small role on superstructure response when the substratum was relative stiff and the box foundation embedment was shallow.The weak intercalation could reduce the seismic response of superstructure.Acceleration and damage of superstructure under low frequency earthquake was larger than that under high frequency blast earthquake.At the same time,in some special cases,the computed results under the fixed base assumption were not always on the safeside.