重力对土体中地下结构地震反应的影响

为解决地震作用下土体重力与地下结构相互影响问题，首先，归纳重力对土体性质的影响规律，分析重力和地震反应的相互影响、地应力的处理和重力的施加方式等; 然后,通过典型算例对重力施加方式的适用性、重力对地震反应的影响程度等进行评价。结果表明： 1）在地震作用下，地下结构的重力和地震反应相互影响； 2）在进行数值计算时，重力可采用时程荷载的形式施加，并且宜保持重力加速度一直不变； 3）当土体为非线性介质时，采用叠加原理进行计算存在误差，且叠加误差随着土体非线性程度的增加而增大，但并非单调增加，叠加误差还受地震波、场地等因素影响。

Influence of Gravity on Seismic Response of Underground Structures in Soil

In order to study the mutual effect of soil weight and underground structure under earthquake, the effecting rules of gravity on soil properties are summarized, and then mutual effect of gravity and seismic response, treatment of crustal stress and way of adding gravity are studied. Finally, the applicability of adding gravity, effecting extent of gravity on seismic response are evaluated through typical computational examples. The results show that:(1)Under earthquake, the gravity of underground structure and seismic response effect mutually. (2)In numerical calculation,gravity is added by the form of loading time history. (3)When the soil is nonlinear medium, calculation exists error by using superposition principle. And the errors become larger along with the increment of soil nonlinear extent, but not monotone increase, which is affected by various factors such as seismic wave, engineering site and so on.