Lateral Testing of Bridge Abutment Backwall with 8' Sandy backfill Test 1

A reinforced concrete abutment backwall specimen with dimensions of 15 ft in width, 8.5 ft in height and 3ft in thickness was pushed under quasi static lateral loading into a 8.0 ft high, densely compacted SE 30 backfill material according to Caltrans bridge design specifications. Wingwalls were simulated using sheets of plywood material furnished with several layers of PVC foil to minimize wall soil interface friction. A set of 6 actuators was installed between the backwall and a high capacity reaction block in horizontal and diagonal arrangements to displace the wall laterally and prevent any uplift movement. The test was controlled using the MTS Flextest GT software. The backfill material was compacted with a vibratory roller to an average compaction of 96%. The backfill was also furnished with low strength gypsum columns to investigate the location of the soil failure surface. The test was performed under displacement control with increasing displacement of up to 12.5 inches. Small loading-reloading cycles were applied at each displacement level, but not allowing soil gapping.