I suspect you will be able to import 1 GB file through phpmyadmin But you can try by increasing the following value in php.ini and restart the wamp.
post_max_size=1280M
upload_max_filesize=1280M
max_execution_time = 300 //increase time as per your server requirement.
You can also try below command from command prompt, your path may be different as per your MySQL installation.
C:\wamp\bin\mysql\mysql5.5.24\bin\mysql.exe -u root -p db_name < C:\some_path\your_sql_file.sql
You should increase the max_allowed_packet of mysql in my.ini to avoid MySQL server gone away error, something like this
max_allowed_packet = 100M