<?php
$params = explode('&', $url, 2);
// вывод
Array
(
[0] => posts-new/test/
[1] => page=2&var1=1&var2=2
)
<?php
$params = explode('&', '/posts-new/test/?page=2&var1=1&var2=2', 2);
array(2) {
[0]=>
string(23) "/posts-new/test/?page=2"
[1]=>
string(13) "var1=1&var2=2"
}