受相邻上部结构影响的隧道-土体系振动台试验研究

为了研究在上部结构存在下隧道与土体的地震响应规律,以地表建筑结构和地下上下平行隧道体系为背景,在软土场地上进行了隧道-土-相邻上部结构体系振动台试验。先介绍了整体试验的概况,包括振动台性能和模型材料,模型各物理量的动力相似关系,模型结构的尺寸,并参照已有研究选定了模型箱内部的边界条件,模型中传感器的位置以及适合该场地的地震波和加载制度。然后,分别从加速度和变形两方面对上下平行隧道与土的地震响应进行分析。在上部结构存在条件下,试验数据表明:①土体加速度峰值沿深度整体自下而上增大,隧道上部土体的加速度增大明显,随着输入加速度峰值的增大,土体的加速度放大系数减小;②在地震波作用下,上隧道的加速度反应大于下隧道,且上隧道的拱腰、拱脚部分与下隧道的拱肩、拱脚部分应变峰值最大。

Shaking-table tests for seismic response of tunnel-soil system affected by adjacent upper structure

In order to study seismic response laws of a tunnel-soil system under existing upper structure, a ground surface structure and underground upper and lower parallel tunnels system were taken as background, shaking-table tests were conducted for a tunnel-soil-adjacent upper structure system on soft soil site.Here, the general situation of the overall experiment was introduced including shaking table performance and model material, dynamic similarity relations of model’s various physical quantities, model structure sizes, boundary conditions inside model box chosen according to existing studies, positions of sensors in model, and seismic waves suitable for the site and loading scheme.Then, seismic responses of upper and lower parallel tunnels and soil were analyzed from two aspects of acceleration and strain under existing upper structure.The test results showed that soil’s peak acceleration value increases from bottom to top along depth and soil’s on upper part of tunnel increases obviously, while with increase in input peak acceleration value, soil’s acceleration amplification coefficient decreases; under action of  seismic waves, acceleration response of upper tunnel is larger than that of lower tunnel, peak strain values of upper tunnel’s arch waist and arch foot as well as lower tunnel’s arch shoulder and arch foot are the maximum.