LATERAL EARTH PRESSURE ON A BRIDGE ABUTMENT

THE LATERAL EARTH PRESSURES ON THE ABUTMENTS OF A 110M LONG REINFORCED CONCRETE FRAME BRIDGE HAVE BEEN MEASURED DURING THE COMPACTION OF THE BACK FILL AS WELL AS AFTER THE COMPLETION OF THE BRIDGE. THE BACK FILL CONSISTED OF SANDY GRAVEL AND MEDIUM SAND, WHICH WAS COMPACTED IN LAYERS BY A 3.0 TON VIBRATORY ROLLER AND BY A 140KG VIBRATORY PLATE COMPACTOR. MODERATELY HIGH EARTH PRESSURES WERE MEASURED DURING THE COMPACTION OF THE BACK FILL MATERIAL, WHICH INCREASED APPROXIMATELY LINEARLY WITH DEPTH. THE LATERAL EARTH PRESSURES VARIED APPRECIABLY DURING THE YEAR AS THE BRIDGE EXPANDED AND CONTRACTED DUE TO TEMPERATURE VARIATIONS AND SHRINKAGE. THE HIGHEST EARTH PRESSURES WERE MEASURED DURING THE SUMMERS WHEN THEY WERE APPROXIMATELY EQUAL TO THOSE IMMEDIATELY AFTER COMPACTION OF THE BACK FILL. THE LOWEST EARTH PRESSURES WERE MEASURED DURING THE WINTER WHEN THE BRIDGE CONTRACTED. LARGE DAILY VARIATIONS OF THE LATERAL EARTH PRESSURES CAUSED BY EXPANSION AND CONTRACTION OF THE BRIDGE WERE ALSO OBSERVED. /TRRL/