<?php
$input = 'line1
line2
line3
line4
line5
line6
line7
line8
line9
line10
line11
line12';
$txtcontent = explode("\n", $input);
$input = array_chunk($txtcontent, 9, false);
foreach($input as $key => $array){
    foreach($array as $k => $v){
        $input[$key][$k] = '\text '.($k*6+1).',1,'.$v;
    }
}
function array_flatten($array) { 
  if (!is_array($array)) { 
    return FALSE; 
  } 
  $result = array(); 
  foreach ($array as $key => $value) { 
    if (is_array($value)) { 
      $result = array_merge($result, array_flatten($value)); 
    } 
    else { 
      $result[$key] = $value; 
    } 
  } 
  return $result; 
} 
$array = array_flatten($input);
print_r($array);
?>