软黏土中含桩地下结构地震响应离心试验模拟

Centrifugal mode tests on seismic response of underground structures with pile foundations in soft clay

针对大空间含桩地下结构(如地下车行系统)在地震作用下的动力响应特性以及场地震陷、结构上浮等危害展开离心振动台试验。试验采用饱和软黏土作为地基土,设计了自由场、整体浅埋地下结构以及等效单元浅埋地下结构3种试验情况,利用层状剪切箱消除边界反射效应,在50g的离心加速度下开展水平地震试验。试验结果表明,不同结构在地震过程中会产生自振在特定的频率区段放大响应,在整体质量、静态浮力及转动惯量等效的前提下,整体结构相对单元结构形式能够降低地震作用下结构的自振效应,且整体结构具有更好地震后抗浮性能。

The centrifuge shaking table tests are conducted to investigate the dynamic response characteristics of large underground structures with piles,such as underground transportation systems,under seismic loading.In addition,the potential hazards like ground liquefaction and structural buoyancy are examined.The saturated soft clay is used as the foundation soil in the tests,which are designed to represent three scenarios:free field condition,integrated shallowly-buried underground structure,and equivalent single-cell shallowly-buried underground structure.To eliminate the boundary reflection effects,a layered shear box is utilized.The horizontal seismic tests are conducted at 50g centrifugal acceleration.The test results indicate that different structures amplify the response at specific frequency bands associated with their natural vibrations.Under the premise of the equivalent overall mass,static buoyancy and moment of inertia,the integrated structure reduces the effects of the natural vibrations during seismic events compared to the single-cell configuration and exhibits superior post-seismic buoyancy resistance properties.