Innovative Bottom-Up Retaining Wall Constructed in Slickensided Red Bed Material

A permanent, tied back soldier pile and lagging retaining wall has been constructed along the West Virginia Route 2 (WV2) roadway in Wellsburg, West Virginia, as part of the Wellsburg Bridge project. The new bridge allows for the crossing of the Ohio River to connect Wellsburg, West Virginia, to Brilliant, Ohio. An expansion of the original two-lane WV2 roadway was required to allow for inclusion of entry and exit lanes to the bridge. The portion of WV2 requiring expansion is located along a mountainside that has evidence of historical deep-seated slope failures. Limitations in the existing topography required the use of a fill wall to allow for additional width of WV2. However, due to the historical deep-seated instabilities at this location, the type of wall to meet project global stability is limited. A thin creep zone of low residual strength material, known as the Pittsburgh red beds, is located at the soil-rock interface. This problematic material was a key driver of the retaining wall design, requiring innovative methodologies to design the wall and careful considerations for construction to confirm design criteria was met. This paper will summarize the design considerations and challenges faced during construction of this 1,219 m (4,000 ft) long, 12.2 m (40 ft) high retaining wall. Advanced numerical analyses considering the complex subsurface stratigraphy and construction staging required for construction of the soldier pile systems provided an optimized design for the client. Challenges included those associated with an atypical bottom-up construction of a tieback wall that were solved by using low tieback lock-off loads to allow soldier pile movement as the backfill was placed. This resulted in the final position of the top of the soldier piles within project tolerance in most cases. Instrumentation was utilized along with Schnabel's infrastructure monitoring service (IMS) to track the performance of the wall through construction and to compare measured movements to those predicted by analysis including numerical models of the staged construction.