为了研究长盾构隧道在考虑行波效应的地震动作用下的纵向响应规律,以上海沿江通道盾构隧道为原型,利用多功能振动台台阵系统,设计并完成了盾构隧道的多点振动台模型试验。鉴于长大盾构隧道工程规模和多点振动台试验系统的能力,试验几何相似比确定为1∶60;基于Buckingham-π定理以及量纲分析方法,确定了试验所需的土与结构的动力相似关系;为了模拟沿隧道纵向的行波输入,设计并制作了节段式模型箱,箱体总长22m,分为4个主动箱以及3个从动箱,箱体之间通过弹簧铰相连;以砂子和锯末按照一定质量比拌合来优化配置模型土,并通过室内三轴试验进行测试验证;考虑土-结构相对刚度相似比为控制指标,选取PE材料作为模型材料;根据刚度等效原理,设计并制作了盾构隧道的多尺度结构模型。试验以上海人工波为地震动输入,通过一系列工况的多点振动台试验模拟,得到了行波效应下盾构隧道模型结构的地震响应规律。试验测试数据包括行波效应下模型土和模型结构的加速度响应、隧道管环环缝的伸缩量响应等。对比分析了一致输入和行波输入下隧道结构的动力响应。试验结果表明:相比一致激励输入,行波效应会明显放大模型结构的加速度响应和环缝变形响应,从而对隧道抗震产生不利影响;地震动非一致激励应该在盾构隧道的纵向抗震设计中得到足够重视。
In order to investigate the longitudinal seismic response law of long shield tunnel in consideration of wave-passage effect,taking the Shanghai Riverine Passage Shield Tunnel as a prototype,a series of multi-point shaking table tests were designed and conducted by the multifunctional shaking table array.In consideration of the scale of the actual shield tunnel andthe capability of the multi-point shaking table system,the geometry similitude ratio was identified as 1∶60.Based on Buckingham-πtheory and dimensional analysis,dynamic similitude relations of model soil and model structure used in the tests were determined.To simulate the longitudinal wave-passage input along the tunnel structure,segmental model container was designed and fabricated.The total length of the container was 22 m,made up of 4driving boxes and 3driven boxes.The boxes were connected by spring hinges.A mixture of sand and sawdust with the certain mass ratio was used to optimize model soil,and was validated through dynamic tri-axial tests.PE was selected as the model material and the similitude ratio of soil-structure relative stiffness was considered as a controlling index.By dint of the stiffness equivalency theorem,a multi-scale structural model of the shield tunnel was designed and fabricated.During the tests,Shanghai artificial wave was regarded as input.The seismic response regularities of shield tunnel models under wave-passage effects were evaluated through a series of multi-point shaking table tests.Test data including acceleration response of model soil and model structure as well as deformation response of circumferential joints in the tunnel was recorded.Dynamic responses of the tunnel structure under uniform input and wave-passage input were compared and analyzed.The results show that the seismic excitation considering wave-passage effect significantly aggravates the acceleration response of segments in the tunnel and the deformation response of circumferential joints,resulting in the risk of the failure of the tunnel during eart