We can disable the back navigation by adding following code in the webpage. Now the catch here is that you have to add this code in all the pages where you want to avoid user to get back from previous page. For example user follows the navigation page1 -> page2. And you want to stop user from page2 to go back to page1. In this case all following code in page1.
<script type="text/javascript">
window.history.forward();
function noBack() { window.history.forward(); }
</SCRIPT>
</HEAD>
<BODY onload="noBack();"
onpageshow="if (event.persisted) noBack();" onunload=""></script>