The fancy agricultural term for this is a "clamp".
I am sorry, but the term "Clamp", near as I have been able to tell describes a pile of potatoes on top of the ground and covered with straw and plastic. Unfortunately such a set up will not keep the potatoes from freezing in climates like I have here. The winters are cold with temps down to minus twenty or lower some years and I have seen it be below zero for three weeks at a time. The frost penetrates when this happens. Water lines are put over 3 feet below grade in this country to prevent freezing.
The potatoes in my pit will be 14 inches below grade and then I will add some insulation over that , leaves or straw. If we get snow, as we usually do before zero Temps, then that also adds insulation. I have never had my potatoes freeze in this kind of pit, in spite of our nasty weather.
Gardening at 5000 feet elevation, zone 4/5 Northern Utah, Frost free from May 25 to September 8 +/-