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为研究非一致地震激励下沉管隧道的响应,以在建的港珠澳大桥沉管隧道为背景,基于由4台面振动台组成的线状多功能试验系统,开展了超长沉管隧道的多点振动台模型试验。鉴于超长沉管隧道工程规模和多点振动台试验系统的能力,研究了试验所需土与结构动力相似比关系,设计并制作了节段式模型箱,用于模拟沿隧道轴向的非一致地震动输入。该模型箱由4个主动箱和8个随动箱组成,总长40m。通过开展离散多点非一致激励空箱振动台试验,验证了通过节段式模型箱将离散多点输入机制转化为连续多点输入机制的可行性。基于室内动三轴试验,测试并确定了最优模型土的配制方案。综合结构惯性力和土-结构相对刚度比的相似分析,通过多种材料比选,最终选用铝合金浇铸件加工模型隧道。试验采用的隧道节段模型尺寸(长×宽×高)为600mm×375mm×170mm,总共98个,隧道模型总长达36.75m。选用与橡胶力学性质相似的硅胶条模拟隧道管节接头的GINA橡胶止水带。通过一系列工况的多点振动台试验模拟,系统获得了沉管隧道模型的非一致激励地震响应规律。通过多工况试验数据分析,分别得到了场地、隧道管节的加速度和隧道管节接头的变化情况,结构纵向加速度响应数据表明行波效应明显。试验结果表明:在常规设计地震(ODE),最大设计地震(MDE)和罕遇设计地震(RDE)的地震强度下,管节接头的变形量均小于允许值,说明隧道结构处于安全状态。
In order to study the response of submerged tube tunnel under non-uniform seismic excitation, taking the immersed tunnel of Hong Kong-Zhuhai-Macau Bridge under construction as background and based on the linear multi-function test system consisting of 4 surface shaking table, Multi-point shaking table model test. Considering the scale of the long immersed tunnel project and the capability of the multi-point shaking table test system, the relationship between the soil-structure power and the required ratio of the test is studied. A segmented model box is designed and manufactured to simulate the axial non- Uniform ground motion input. The model box consists of 4 active boxes and 8 following boxes, total length 40m. Through the experiment of discrete multi-point non-uniform excited empty box shaker, the feasibility of converting discrete multi-point input mechanism into continuous multi-point input mechanism by using segmented model box is verified. Based on the indoor dynamic triaxial test, the optimal soil preparation scheme was tested and determined. Based on the similar analysis of inertia force and soil-structure relative stiffness ratio, a variety of material comparison and selection, the final selection of aluminum alloy casting mold tunnel. The tunnel segment model size (length × width × height) used in the experiment is 600mm × 375mm × 170mm, a total of 98, the total length of the tunnel model is 36.75m. GINA Rubber Water Stop Belt, which simulates the joints of tunnel joints, is made of silicone rubber with similar mechanical properties to rubber. Through a series of multi-point shaking table test simulations, the non-uniform excitation seismic response law of immersed tunnel model was obtained. Through the analysis of multi-conditions test data, the accelerations of tunnel joints and tunnel joints are obtained respectively. The longitudinal acceleration response data show that the traveling wave effect is obvious. The experimental results show that the deformations of joints are less than the allowable values under the seismic intensity of conventional design earthquake (ODE), maximum design earthquake (MDE) and rare design earthquake (RDE), which indicates that the tunnel structure is in a safe state.