use sub-path url in php

My page's url is http://www.mydomain.com/channelname1/blog. it is panel page.
I also created a node content view which list the lastest blog post in another page. In the view, I want to add a more button which link to http://www.mydomain.com/channelname1/blog. my php code is

print '<div class="more-link">'. l(t('more'), arg(1) .'/blog') .'</div>';

but when I click 'more', it linked to http://www.mydomain.com/30/blog.
I think 30 is the nid. So how I can replace 30 to channel name?

Thanks.