Forensic Analysis of a Distressed RE Wall and Rigid Pavement in a Newly Constructed Highway Approach

Abstract

The current study details structural damage to a newly constructed rigid pavement and reinforced earth (RE) walls, as well as the corrective measures employed. When construction of the RE wall began and reached 1 m above the existing ground level, the client has decided to build a box culvert across the highway, for uninterrupted passage of rainwater across the highway. The bottom of the box culvert was 7 m below ground level. After the construction of box culvert, the surrounding soil below the ground level was not properly compacted due to accessibility constraints. As a consequence, a 5 mm-wide crack in the rigid pavement over the RE wall was observed just before opening for traffic. Moreover, the RE wall had fascia settlement of about 25–65 mm on both sides. Furthermore, around 150 mm gap between Pavement Quality Concrete (PQC) and Dry Lean Concrete (DLC) layers was also noticed over few meters along the approach. A forensic investigation was sought to understand the causes of distress of RE wall and rigid pavement. Non-destructive testing, such as Multichannel Analysis of Surface Waves (MASW) and Ground Penetrating Radar (GPR) testing were conducted to assess the condition of backfill and foundation soil. The investigation revealed that the damage was primarily caused due to improper compaction of soil below ground level and adjacent to the box culvert. Pressure grouting of the subsoil in the vicinity of the box culvert and the gap between PQC and DLC layers was resorted to. Further as a safety measure, a simple load test was conducted on DLC layer beyond opening the highway for traffic, and the settlement of DLC layer was found negligible. In addition, the DLC layer settlement was continuously monitored during traffic loading, and no settlement has been observed even after 60 days.