php 合并数组内的字母 组成新的单词

Question

foreach ($d[3] as $k2 => $v2) {
  for ($i=0;$i<strlen($v2);$i++) {
  $value[$k2][] = $v2[$i]; 
  } 
 }

$value有三个数组分别为["a","b","c"]["b","c","a"]["x","y","z"] 我想让这三个数组安照一样的顺序两两合并为数组["abbcca","axbycz","bxcyaz","bacbac","xaybzc","xbycza"]应该怎么做，谢谢解答