php语法中如何增加数组的维度

<?php
header("Content-type:text/html;charset=utf-8");
$arr=array("vue","html","css3","node","php","mysql");
echo "原一维数组：";
var_dump($arr);
 
$chunk=array_chunk($arr,count($arr)/2);
echo "将一维数组转为二维数组：";
var_dump($chunk);
?>