push an associative arrays as a one associative array

I have this desired associative array format (refer below)

$url = array (
    "a1" => array(
        'k1' => "content of k1 in a1 array",
        'k2' => "content of k2 in a1 array"
    ),
    "a2" => array(
        'k1' => "content of k1 in a2 array",
        'k2' => "content of k2 in a2 array"
    ),
);

and in Laravel thing, I retrieved a records in a database table and loop on it and then get its value and push it unto an array.

$k = kk::with('kk_names')->get();
$k_array = array();
foreach($k as $item){
    $sr = array($item->name => array("k1" => $item->items[0]->description,"k2" => $item->items[1]->description))
array_push($k_array,$sr);
}

it did works but the associative array format (refer above associative array format) was not the one I want, it gives me this instead.

$url = array (
    array("a1" => array(
        'k1' => "content of k1 in a1 array",
        'k2' => "content of k2 in a1 array"
    )),
    array("a2" => array(
        'k1' => "content of k1 in a2 array",
        'k2' => "content of k2 in a2 array"
    )),
);

any ideas, help please?

via Chebli Mohamed