Operator on #34226 Cat loader was loading out 3 haulers in the DII area pit just west of the #4 ramp. As he was loading #32039 hauler, a spoil slide occurred (approx 120' long by 45' wide). The slide pushed the rear of the hauler over approx 3' into loose coal causing the hauler to become stuck. The loader & haul operator along with two others were able to walk to a safe location.