All 18 elements in one group? ..or 3 repeat groups by 6 elements?there are 18 elements
2nd group elements have the same name as first group elements?
For each repeating group you have to do new table and irretate through group elements.
And maybe will be easier to do:
<?php if ($element_data1[0] == '0') {
$intervento1 = '' ;
}
echo $intervento1;
?>