Import Export SiteCollection using STSADM

Export:

stsadm -o export -url http://localhost/sites/recovery -filename recovery.export -versions 4 -includeusersecurity

Create Site Collection:
Create a site collection because IMPORT command doesn't create a new site collection

stsadm -o createsite -url http://localhost/sites/recovery_copy -owneremail administrator@company.com -ownerlogin domain\administrator -sitetemplate STS#1

Import:

stsadm -o import -url http://localhost/sites/recovery_copy -filename recovery.export -includeusersecurity

Note :
Please note import / export is only used to backup/restore a sub-web ( SPWeb ). For backup/restore of site collection you will need Backup / Restore commands from STSADM or Powershell