Backup and Restore Site collection using powershell

clear-host

Add-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction SilentlyContinue

Backup-SPSite "http://abc.com/sites/bcd" -Path "C:\backups\kmt\bcd.bak"

Restore-SPSite http://server_name/sites/site_name -Path C:\Backup\site_name.bak