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

In simple, if there is an existing tunnel, kindly activate it (All tunnel elements) in the initial stage. Then, add loading stages later.

If you have modelled tunnel right now and want to predict the deformations under seismic loading, then don't activate the tunnel element in the initial stage. Rather activate it by stage-wise construction as usually carried out for tunnelling. Then add seismic loading

Kousik M P | Geotechnical engineer | India 

Thanks sir.

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

Thanks Dennis. 

Yes exactly, Thanks