INFLUENCE OF FREEZING RATE ON FROST HEAVING

THE MAJOR THERMAL INFLUENCES ON THE FROST-HEAVING PROCESS IN SOILS ARE REVIEWED. LABORATORY EXPERIMENTS THAT ARE DESIGNED TO PREDICT THE FROST SUSCEPTIBILITY OF SOIL IN THE FIELD ARE SHOWN TO BE STRONGLY INFLUENCED BY THE FREEZING PROCEDURE. IT IS BELIEVED TO BE MISLEADING TO COMPARE THE FROST SUSCEPTIBILITY OF DIFFERENT SOILS BASED ON FREEZING TESTS THAT ARE CARRIED OUT AT THE SAME RATE OF FROST LINE PENETRATION. APPLYING THE SAME RATE OF HEAT REMOVAL IS THOUGHT TO GIVE MORE MEANINGFUL COMPARISONS OF FROST SUSCEPTIBILITY. IN GENERAL, INCREASING THE RATE OF HEAT REMOVAL CAUSES THE HEAVING RATE TO RISE TO A MAXIMUM FOLLOWED BY A REDUCTION THAT INTERCEPTS THE IN-PLACE PORE WATER PHASE CHANGE EXPANSION LINE. ARAKAWA'S CONCEPT OF ICE SEGREGATION EFFICIENCY IS INTRODUCED, AND ITS USEFULNESS FOR ASSESSING FROST SUSCEPTIBILITY IS DISCUSSED. THE ICE SEGREGATION EFFICIENCY RATION, E, GIVES THE FRACTION OF THE HEAT REMOVED FROM THE FREEZING FRONT IN THE SOIL THAT IS DIRECTLY ATTRIBUTABLE TO ICE LENS FORMATION. WHEN E=1, THE TOTAL HEAT EVOLVED IS FROM THE PHASE CHANGE INVOLVED IN ICE LENS FORMATION; WHEN E HAS A VALUE BETWEEN ZERO AND ONE, ONLY A PART OF THE HEAT EVOLVED IS DERIVED FROM ICE LENS FORMATION; AND WHEN E=0, NO ICE LENSING OCCURS. FINALLY, SUGGESTIONS ARE MADE FOR THE IMPROVEMENT OF FROST-SUSCEPTIBILITY TESTS IN THE LABORATORY. /AUTHOR/