Effects of Traffic Loading on Seasonal Temperature Change-Induced Problems for Integral Bridge Approaches and Mitigation with Geosynthetic Reinforcement

Approach slabs are commonly used to smooth the transition between an integral bridge abutment and its adjacent backfill-supported pavement where differential settlement may exist. This settlement can be aggravated by abutment cyclic movements caused by seasonal temperature changes. When the backfill surface settlement near the abutment is large enough to create a void under the approach slab, traffic loads on the approach slab are transferred to the abutment and the end of the approach slab near the adjacent pavement. Differential settlement may also develop at the joint between the approach slab and the adjacent pavement due to traffic loading. Sleeper slabs on geosynthetic-reinforced soil have been proposed to be placed underneath the joint to mitigate this differential settlement. However, no physical model test has been conducted so far to investigate the effects of traffic loading on the approach slab and the mitigation benefits of geosynthetic reinforcement under the sleeper slab. In this study, three physical tests were designed and conducted to fill this knowledge gap. This study found that compaction of the backfill by contact stresses under the approach slab and movements of the abutment due to traffic loading caused backfill surface settlement. As the backfill surface settlement increased, the contact stresses under the approach slab and the sleeper slab decreased. Geosynthetic reinforcements under the sleeper slab reduced the contact stresses under the approach slab, thus minimizing the settlement, but increased the contact stresses under the sleeper slab. In addition, the geosynthetic reinforcements significantly reduced the differential settlement between the two sides of the sleeper slab.