From The Document Foundation Wiki
If you want to combine several ASCII files into a single sheet, follow this procedure:
- Open an empty spreadsheet.
- Go to ▸ .
- Select the File Type that you want (Text CSV .txt, dbase, etc.)
- Search for the file you wish to open.
- Click on the Insert button to close the window.
- Set the parameter in the Text import window as shown above.
- Click OK.
- Repeat the procedure from 2) for the other files.