双仓综合管廊抗震性能模型试验研究

Model tests on seismic performance of double-box underground utility tunnel

利用振动台试验系统,基于模型试验相似理论开展了双仓地下管廊的抗震性能试验研究。试验中,采用1952年Taft地震波作为输入地震波,并将其输入加速度峰值调整为0.2g,0.4g,0.8g和1.2g,以考虑不同PGA(peak ground acceleration)的影响。通过分析试验数据得知,管廊侧壁最大动土压力响应沿深度呈倒立"W"形分布,振动后管廊结构与周围土体之间的土压力场发生了改变;管廊侧壁土体中最大加速度响应随输入PGA增大而增大,沿深度整体呈减小趋势,加速放大系数为0.5~1.5;从加速度时程曲线和傅里叶谱来看,管廊侧壁结构与其周边土体的加速度响应基本一致,在15~30Hz的频段土体中的振幅稍大于结构;地震过程中,结构拐角处产生较大的弯矩响应,且随输入PGA的增大而增大。同时结合ABAQUS数值软件开展了数值模拟研究,以和模型试验结果开展对比比较,结果表明试验结果具有较高的可靠性。

A shaking table model test on a double-box underground utility tunnel is conducted based on the theory of similarity simulation test to investigate its seismic behavior. In this test, the Taft earthquake spectra, which are adjusted to have the peak accelerations of 0.2 g, 0.4 g, 0.8 g and 1.2 g, respectively to consider the effect of various peak ground accelerations(PGAs), are chosen as the input seismic ones. It is concluded that the maximum dynamic earth pressure has a distribution of reverse "W", and the earth pressure field changes at the end of earthquake. On the whole, the maximum acceleration response, with the amplification from 0.5 to 1.5, increases with an increasing input PGA and decreases with depth. According to the time histories of acceleration and the Fourier spectra, the structures and the surrounding soils basically have consistent acceleration response at the same depth, and the amplitude of the soils is greater than that of the structures under the frequency from 15 to 30 Hz. During the earthquake, there is a larger response of bending moment at corners of the structures, which increases with the input PGAs. At the same time, numerical simulations are carried out with ABAQUS to compare with the results obtained from shaking table tests, which suggests that the results obtained from shaking table tests are highly reliable.