振动台试验中地下结构地震响应预测方法
Prediction method for seismic responses of underground structures in shaking table tests
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摘要: 考虑土–结构相互作用的地下结构大型振动台试验成本极高,周期长,通常难以在短期内多次重复开展,为保证试验顺利开展,在试验前对其响应开展预测工作具有重要意义。采用完全数值模拟进行预测的方法在模型试验中已得到广泛的使用,但这种方法有时会产生较大误差,特别是对于强非线性的地下结构振动台模型试验。为提高预测方法的准确性,提出了一种整体式反应位移法数值模拟与自由场试验相结合的方法来预测地下模型结构在振动台试验中的地震响应。首先,介绍采用自由场振动台试验获取整体式反应位移法计算参数的方法,基于此,分别采用所提出方法和传统全数值方法预测某地铁车站结构模型在振动台试验中的地震响应,并将预测结果与后续试验结果进行对比。结果表明:所提出方法预测结果准确性较传统全数值方法预测结果准确性有大幅提升,方法可用以定性地预测后续试验结果,并可在一定程度上指导和完善后续试验方案。Abstract: The large-scale shaking table tests on an underground structure embedded in soil need extremely high cost and long test period, and usually they can hardly be frequently conducted in a short time. In order to successfully conduct the tests, predicting their responses before the tests is meaningful. The fully-numerical prediction method has been widely applied in model tests, but sometimes the results may have a great error, especially under the strong non-linear condition. To improve the accuracy of the prediction, the method combining both the numerical analysis and the free-field shaking table tests is proposed to predict the seismic responses of underground model structures in shaking table tests. The method using the data of the free-field tests to estimate the parameters for the Integral Responses Displacement Method is firstly introduced. The seismic responses of underground model structures in shaking table tests are predicted using the proposed method and the traditional fully-numerical prediction method. The predicted results are then compared with those by the subsequent tests. It is shown that the accuracy of the predicted results by the proposed method is greatly improved compared with that by the traditional fully numerical method. The proposed method can be used to qualitatively predict the seismic responses of underground structures in shaking table tests and further improve the design of the subsequent tests.