THE BEHAVIOR OF A PIER FOUNDATION IN A SWELLING CLAY

OBSERVATIONS OF THE MOVEMENT OF THE PIER AND BEAM FOUNDATIONS OF A BLOCK OF FLATS BUILT ON A SWELLING CLAY IN A SUBURB OF ADELAIDE ARE PRESENTED. OVER A PERIOD OF SEVEN YEARS, THE FOUNDATIONS HAVE SUFFERED UPLIFT RANGING UP TO TWO INCHES IN PLACES AND AT THE BEGINNING OF 1968 MOVEMENT IS STILL CONTINUING AT A STEADY RATE. THEORETICAL CONSIDERATIONS SUGGESTED THAT THE PIERS HAD EITHER FAILED IN TENSION, OR WERE BEING LIFTED BY THE SWELLING OF THE DEEPER LAYERS OF CLAY AS A RESULT OF A RISING WATER TABLE. EXAMINATION OF ONE OF THE PIERS THROUGHOUT ITS LENGTH REVEALED NO SIGN OF FAILURE, WHEREAS SUBSEQUENT MOVEMENT OBSERVATIONS HAVE PROVIDED STRONG SUPPORT FOR THE SECOND OF THE ABOVE ALTERNATIVES. CHANGES IN THE DESIGN OF PIERS ARE EXAMINED IN THE LIGHT OF THE CONCLUSIONS DRAWN FROM THE STUDY. /AUTHOR/