Is it possible to have the service collecting the responses from participants on a webserver in a separate network zone separate from the admin server?

Yes,

Not an issue : LimeSurvey auto adapt according to the current webserver alias used.

Just remind to set publicurl : www.limesurvey.org/manual/Optional_setti...vanced_path_settings

I want to use 3 tier architecture and deploy a separate webserver in public network for end-users to access the published surveys and another application server in our private network to create and manage surveys.
Is it supported to publish the created surveys files to the webserver (the server in public netwok) and when end-users open the surveys, they access this webserver to fill up the published survey and submit their responses?

Yes,

Just try …