Insert several lines in field collection programmatically
First be sure that that field in your field collection field setting accept multi value then try save your item with 

  $node-&gt;field_fc_intervenant_tab['und'][] = array('value' =&gt; $field_collection_item-&gt;item_id,
    'revision_id' =&gt; $field_collection_item-&gt;revision_id,);


and finally be something like 

if(!empty($intervenant)) {    

    // you should have $node here
      $field_collection_item = NULL;
      $field_collection_item = entity_create('field_collection_item', array('field_name' =&gt; ''field__doc_fc_intervenant_tab '));
      $field_collection_item-&gt;setHostEntity('node', $node);
      $field_collection_item-&gt;save(TRUE);
          foreach ($intervenant as $val) {
             if($val != null) {
      $node-&gt;field_fc_intervenant_tab['und'][] = array('value' =&gt; $field_collection_item-&gt;item_id,
        'revision_id' =&gt; $field_collection_item-&gt;revision_id,);
}
}
    $fieldcollection-&gt;save();
}