Study On Seismic Dynamic Response Of Lebuguolaji Tunnel In Ya'lu Expressway

Along with the implementation of West Development Strategy, a lot of tunnels for highways, railroads, and water and electricity projects will be built in strong seismic regions. Does the dynamic response of mountain tunnel follow any rules under strong earthquake? Is the tunnel safe when it is constructed in strong seismic regions? How to make earthquake resistance and damping designs? All these are the concerned problems of a project designer. It is of great actual value to study the seismic responses and the vibration-absorption measures of the shallow buried mountain tunnel built in the strong seismic regions. This paper's contents are summarized as Following:1. The seismic dynamic responses of the Lebuguolaji tunnel portals were numerically simulated. And the rules of variation of the peak value of displacement and internal force were analyzed and compared. Meanwhile, the rules of seismic dynamic responses of the mountain tunnels located in strong seismic regions in are studied in particular.2. Two kinds of grouting measures are adopted on the tunnel portals, including partial grouting measure and grouting around the tunnel with a distance from the lining measure. The seismic dynamic responses rules of the peak value of the displacements, the peak value of the internal force and the variation of the plasticity regions were compared between the portal after grouting and the original design. The vibration absorption effects of the measures on mountain tunnels, which located in strong seismic regions, were studied in particular.By the above study, the following conclusions are reached:1. There is a dislocation between the two lines of the tunnel. The peak values of the horizontal displacements and the internal forces mostly appear in portal of signal line part of the double-line tunnel (the dislocation part). The seismic dynamic responses are very patency in this part. It should be put attention to the seismic fortification of this part of tunnels. 2. The vibration absorption effects of the measures are obvious near the portal. When it is far from the portal, the effects are inconspicuous.3. The measure of partial grouting could reduce the peak values of the displacements, the peak value of the internal forces and the plasticity regions near the portals, and reform distributing rules of internal forces of the transect of the tunnel lining.4. The measure of grouting around the tunnel with a distance from the lining could weaken the seismic dynamic responses in some degree, and reduce the displacements, the internal forces and the plasticity regions near the portals.