Old thread, but I had the same problem so I figured I'd share my solution!
The link pedrum golriz provided is helpful. We implemented it here: www.learnerds.com
On the destination page, we used this code:
<script>
var url = window.location.href; \\ grabs the complete url with the query strings
var temp = new Array(); \\ creates an array that will store our values
temp = url.split('?'); \\ this function splits the url into 2 parts
\\ temp[0] (everything before the question mark) & temp[1] (everything after the question mark)
disqus_url = temp[0]; \\sets the disqus_url to be the same regardless of query strings
</script>
You could also probably do window.location.href.split('?')[0] for less lines of code.
Hope that helps!