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以福州市二环路金鸡山隧道扩建工程为背景,设计制作了特大断面隧道的1/30缩尺模型,并在福州大学土木工程实验中心的双向地震模拟振动台上,完成了21种工况下的模拟地震动试验。对试验数据进行傅立叶分析,发现浅埋条件下特大断面隧道的存在,显著地改变了原场地的动力特性;第一卓越频率主要体现原场地的动力特性,而第二卓越频率主要体现衬砌结构的动力特性。对试验数据进行频响分析,发现地震波自下而上传播至衬砌结构顶部以后,其第二卓越频率附近的频率成分发生了显著增益;其最大增益频率大致等于第二卓越频率。分析特大断面隧道动力特性与输入地震动幅值的关系,发现经历大振幅地震波激励后,衬砌结构上裂缝发展较为显著,其整体刚度明显降低,从而导致第二卓越频率和最大增益频率出现较为明显的下降。基于上述研究成果,进一步提出了特大断面隧道抗震设防的工程建议。
Based on the expansion project of Jinji Mountain Tunnel in Erhuan Road of Fuzhou City, a 1 / 30th scale model of tunnel with extra large section was designed and manufactured. On the two-way seismic shaking table of civil engineering experiment center of Fuzhou University, 21 kinds of working conditions Under the simulated ground motion test. The Fourier analysis of the experimental data shows that the presence of super-large cross-section tunnel under the shallow buried condition significantly changes the dynamic characteristics of the original site. The first excellent frequency mainly reflects the dynamic characteristics of the original site, while the second excellent frequency mainly reflects the lining structure Dynamic characteristics. Frequency response analysis of the experimental data shows that the seismic wave propagates from the bottom up to the top of the lining structure, and the frequency components near the second excellent frequency have a significant gain; the maximum gain frequency is roughly equal to the second superior frequency. The relationship between the dynamic characteristics of large section tunnels and the amplitude of input earthquakes is analyzed. It is found that the crack development on the lining structure is obvious after the stimulation of large amplitude seismic waves, and the overall stiffness is obviously reduced, which leads to the obvious second frequency and maximum gain frequency Decline. Based on the above research results, the engineering suggestions for seismic fortification of extra large tunnels are further proposed.