砂砾石垫层上部结构地震反应分析

Study on the seismic responses of constructions on sand-gravel cushion

砂砾石垫层属于取材方便、性能良好、造价低、应用广泛的地基处理方法.通过多年对砂砾石垫层现场实验数据的积累,砂砾石垫层不仅可以很好的提高软弱地基的强度,还能起到一定程度的减震作用.应用有限元计算的方法研究砂砾石垫层对上部结构地震反应的影响,选取2个计算模型,分别是钢筋混凝土烟囱和钢筋混凝土框架结构,用时程分析法对两个模型考虑垫层和不考虑垫层的地震反应进行计算,通过比较分析,得出结论,考虑砂砾石垫层后,结构底层的侧向刚度有所减小,在地震作用下,垫层一定程度上起到了滑移减震的作用,上部结构的加速度和位移反应均有减小.

To study the impact the sand-gravel cushion may exert on seismic response of constructions on it, this paper uses 2 models, one is a chimney on the sand-gravel cushion and the other is a reinforced concrete frame structure on the san-gravel cushion. For each model, two computational models were made in finite element method, one is the superstructure with sand-gravel cushion under it, the other is the same superstructure but with rigid foundation. The seismic responses of the 4 computational models were calculated in time history method. By comparing the seismic responses of the chimney and the reinforced concrete frame structure on sand-gravel cushion and their seismic responses with rigid foundation, it was found that with sand-gravel cushion under the constructions, the displacement of the construction at the bottom increased a little while the displacements of the other floors all decreased, and the acceleration responses of the constructions on sand-gravel cushion decreased as well. As the results show, the sand-gravel cushion served as a vibrating isolation in a certain extent, the seismic displacement and acceleration responses of the constructions on it all decreased.