function addHtmlFragment($doc,$parent,$html)
{
$tempDoc=new DOMDocument('1.0','utf-8');
$tempDoc->loadHTML("$html",LIBXML_HTML_NOIMPLIED|LIBXML_HTML_NODEFDTD);
foreach($tempDoc->documentElement->childNodes as $child){
$parent->appendChild($doc->importNode($child,true));
}
}
$doc=new DOMDocument('1.0','utf-8');
$parent=$doc->createElement('div');
addHtmlFragment($doc,$parent,"hoge
");