What will be the staged construction phases if an existing tunnel is modelled which is embedded into the soil under seismic loading?

Dear Manisha,

Generally it's better to use a model for static analysis in the static phases (for instance HSsmall) and change the materials to a model for seismic analysis only when doing the dynamics analysis. 

With kind regards,

Dennis Waterman

if I have to use user-defined models such as PM4sand and Pm4silt, then the same stages to be used, as these models are for dynamic and liquefaction analysis? It will affect the results if I will be using these models in static phase?

Yes exactly, Thanks

Thanks Dennis. 

If you would simply activate the tunnel in the initial stage without modelling the construction process, it is almost certain that the structural forces in that tunnel as well as the soil stresses around the tunnel are incorrect. Which mean that the results of the seismic phase have no meaning.
Hence, your advice is not good modelling practice!

The correct way to do it is to at least model the construction of the existing tunnel in a couple of phases, this can be a simplified construction sequence compared to the real building sequence, then reset the displacements to zero and then do the seismic analysis.

With kind regards,

Dennis Waterman