Get a specific page's excerpt within the loop Wordpress

I am trying to create a loop that loads a random image from any posts, whilst also retrieving the excerp开发者_如何学Got of a specific page. I have done the random post part, but cannot get it to retrieve the page excerpt... I think I may need to query the pages in their own loop but I'm not sure how to do this. I have installed the function to get page excerpt support etc. but I think I am doing something wrong within the loop, any help would be appreciated.

<div class="postimage">
<?php if (have_posts()) :
query_posts('showposts=1&orderby=rand');
while (have_posts()) : the_post(); ?>
<a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><?php the_post_thumbnail('blog-post-image'); ?></a>
  <div class="borderimage"></div>
  <div class="tagline"><h1><?php the_excerpt('$page_id=8'); ?> </h1>
</div>
  </div>
</div>
<?php endwhile; else : endif; ?>

query_posts replaces the global $wp_query, which you don't want to do since you want to keep that query for your page. Try this instead...

if (have_posts()){
    while(have_posts()){
        the_post(); //global $post now has the page in it
        $args = array("posts_per_page"=>1,"orderby"=>"rand");
        $random_posts = get_posts($args); //returns an array
        $random_post = $random_posts[0];
        //do your stuff... 
        //$post contains the original page
        //$random_post contains the random post
     }
}