Abstract: To address the adaptation problem between the precast internal structure and the shield segments for an electric power tunnel, a novel fully precast internal compartment structural design draft based on the grouting rubber capsule is proposed, which could be used to eliminate the problems in the existing plans. The design draft has the merits of self-adapting the assembling tolerances of the shield tunnel and quick assembly with dry connections, etc. However, because the construction site Beijing is located at the region that the seismic precautionary intensity is eight degree, the seismic safety is a critical factor for the selection of design drafts. The seismic responses of the novel structure and their differences compared with the alternative structural plans should be analyzed. In the study, the nonlinear three-dimensional site-tunnel-internal structure finite element models were built based on the proposed
novel design draft, the post-grouting mortar and the cast-in-place design draft. The seismic analyses were conducted using the integrated response displacement method. The structural deformation, connection region deformation and internal force responses were compared. Results show that the deformation of the internal compartment structure was small. It could normally transfer the internal force with good structural stability. Moreover, the flexible rubber capsule arranged between the precast bottom compartments and the segments deformed under the seismic effect in both radial and circumferential directions of the tunnel. It absorbed some
seismic effect which should had been loaded on the internal structure. The axial and shear force responses of the internal structure were drastically decreased. But for the post-grouting mortar design draft, the contact shear stress was concentrated at regions near the circumferential seam. Therefore, the seismic safety of the novel structural design draft is better than those of the two traditional design drafts. In addition, because the grouting capsule have another advantage, such as dry connection and rapid construction, there is a great potential for the proposed novel design draft to be practically used.

Key words: precast internal structure, seismic analysis, electric power tunnel, grouting capsule, precast compartment structure, seismic resistance of electric power infrastructure