饱和砂土地基液化离心机振动台模型试验研究

Dynamic centrifuge tests on liquefaction of saturated sand foundation

通过开展饱和砂土地基水平振动的离心机振动台试验,研究了振动液化过程中砂土地基的动力响应沿深度的变化规律,发现在液化过程中,由于剪切模量的变化,液化土层与下部未液化土层之间将形成反射界面,后续传来地震波所携带的能量将通过该界面反射至下部土层,导致其动力响应显著变大;同时发现土层在经历液化过程后,其抗液化能力会显著提高,但再次地震时,发生过液化的土层的动力响应也将明显增大。研究结果能够加深对于饱和砂土地基中地震动传播规律的认识,同时也可为验证和改进现有评估砂土液化影响的计算方法提供试验数据。

Dynamic centrifuge tests were performed on a uniform saturated sand foundation bed model;dynamic responses of different soil layers with various depths were analyzed. It is found that in the course of sand liquefaction,due to the variation of the shear modules in the liquefaction layer,a reflection interface will form between the liquefaction layer and its neighborhood sand layer,which will reflect energy carried by the subsequent shake wave to the sand layer right below the liquefaction layer,and finally make the dynamic response of the mentioned beneath layer get a notable increase;meanwhile,as for those sand layers that have experienced liquefaction,their liquefaction resistance would get notable improved,but those postliquefaction sand layer will demonstrate greater dynamic response during subsequent earthquakes. The research work will improve our understanding on the propagation law of the shake wave in the saturated sand foundation bed model,and the test data can be used to verify and improve the numerical method for evaluating the influence of liquefaction on a saturated sand foundation.