MECHANICS OF PENETRATION OF PILES INTO PERMAFROST

LABORATORY AND FIELD TESTS HAVE BEEN CONDUCTED TO DETERMINE THE FEASIBILITY OF USING ROCKETS FOR DRIVING PILES. PHASE I CONSISTED OF USING GUNS TO DRIVE HOLLOW CIRCULAR MODEL PILES INTO ARTIFICIAL PERMAFROST. MEASURED PARAMETERS WERE THE PENETRATIONS AND IMPACT VELOCITIES OF PILES HAVING VARIOUS EXTERNAL DIAMETERS. THE MAIN PURPOSE OF PHASE II WAS THE MEASUREMENT OF PARAMETERS IN ORDER TO FIND A PHYSICAL MEANING OF THE EMPIRICAL EQUATION DEVELOPED IN PHASE I. THE FIELD TEST PROGRAM CONSISTED OF DRIVING THIN, HOLLOW, FULL-SIZE PILES INTO NATURAL PERMAFROST USING A ROCKET AS THE DRIVING AGENT, AND MEASURING THE SAME PARAMETERS AS IN PHASE I. THE RESULTS INDICATE THAT USE OF ROCKETS IS TECHNICALLY FEASIBLE. IT IS ESTIMATED THAT A 6 IN. NOMINAL DIAMETER PILE OF 0.56 IN. WALL THICKNESS COULD BE DRIVEN 6 TO 8 FT INTO PERMAFROST BY A 100,000 LB THRUST ROCKET HAVING AN 80 MSEC BURNING DURATION. TO RESIST COLLAPSE UPON IMPACT WITH THE PERMAFROST, THE PILE SHOULD HAVE EITHER A REINFORCEMENT SHOE OR A MINIMUM WALL THICKNESS OF 0.56 IN. A DESIGN OF AN INTEGRATED PILE-ROCKET ASSEMBLY MEETING THESE REQUIREMENTS IS PROPOSED. /AUTHOR/