Hy every one. I have a question about deconfinement method, in particulary would you know if there is some correlation about Mstage and 1-beta ? I learnet that Mstage is a global parameter and 1-beta may change for different case of tunnel's study. Besides we assign 1-beta to the deactiveted cluster to simulate the percentange of unsupported tunnel lining, instead Mstage is the percentage of balance resolved, correct? Thanks for your time.
Best regards,
Pasquale
A deconfinement value can be entered during staged construction as 1-β in the model explorer for any selected and deactivated soil cluster. This method intends to give similar results to those obtained when using the partial staged construction (ΣMstage) method while bringing additional flexibility since different deconfinements can be applied to different tunnels or different sections of the tunnel in the same phase.
The major advantage of the deconfinement option is that different deconfinement values can be applied to different soil clusters (e.g. tunnels with several sections) and, therefore, it adds greater flexibility to the calculation. In addition, in every stage, out-of-balance forces are solved (until the convergence criterion is reached), likely resulting in a more accurate approach.
When using the deconfinement option the soil clusters are completely deactivated and a support pressure is applied. When using the ΣMstage approach only a part of the self-weight of the deactivated soil clusters is effectively removed.
In both approaches, part of stresses resulted from the excavation are only applied when the lining is active. However, rather than applying a distributed load directly to the lining it is a new stress equilibrium for the final configuration, which involves the completed excavation and application of the support/lining.
Hope this helps.
Thaks Faseel for the answer.