Sometimes you need to backup a site collection or wish to perform a restore. This could be done via powershell:
To create a backup from a Sharepoint 2010/2013 site collection use the Backup-SPSite cmdlet:
Backup-SPSite http://SP –Path C:\YourBackup\TheSiteCollection.bak
To restore a Sharepoint 2010/2013 site collection use the Restore-SPSite cmdlet:
Restore-SPSite http://SP –Path C:\YourBackup\TeSiteCollection.bak