From my view point, unfortunately, no.
Public transportation companies are obliged by law to take passengers to their destination (final destination on the ticket) on the same day – even if they have to change trains several times or take a diversion. However, The Swiss Federal Law on Public Transport contains no provisions with regard to compensation for missing flight connections, theatrical performances, concerts, examinations and the like, or for loss of working hours.
Likewise, SBB is exempt from liability if it can prove that the damage was caused by the fault of the person traveling or was due to circumstances that it could not avoid and the consequences of which it was unable to prevent (e.g. accident involving a person, severe weather, rockfall, strike, etc.).
I wondered why it was not possible to take an alternate route as there are mutiple possibilites to get to Chur?
You may try to request a partial refund of your ticket, but not a full refund since your ticket was valid for the entire day. If you will get a partial refund then it is an act of courtesy and not because SBB is obliged to do so, as I explained above.