EMPLOYEE WAS DRIVING AN ARTICULATED DUMP TRUCK WITH APPROXIMATELY 18 TONS OF MATERIAL. AS HE TOOK THE CORNER AT THE MAINTENANCE SHOP TO GO UP THE HILL THE LOAD SHIFTED TO THE RIGHT AND THE DUM P BODY TURNED OVER ON THE RIGHT SIDE. THE CAB WENT ONTO 2 WHEELS THEN CAME DOWN. EMPLOYEE RECEIVED STITCHES TO FOREHEAD.