Port expansion necessitates ever-deeper water to meet the increasing vessel sizes dictated by economics. The industry had met this challenge by introducing new and better materials along with improved construction and fabrication methods.
Typically, filled bulkheads had been desired over pile-supported platform docks because they provide a lower initial construction cost and lower maintenance costs. The bulkheads have generally relied upon tieback Z-sheets or combi-wall systems. Alternatively, in more expensive applications, the use of closed cell or diaphragm systems with flat sheet piles have been used. However, the increase in water depths is approaching or surpassing the practical limit of these wall types.
These structures can have configurations with narrow open cells and long tail walls, which will address even the most severe seismic, height, and soft soil conditions. The OPEN CELL SHEET PILE™ (OCSP) structure provides an economical alternative to other dock types that can meet these challenges. The OCSP structures use 99 percent recycled steel. Used commonly on docks and similar structures, the OCSP bulkhead is a cellular flat sheet pile structure in which each cell’s sheet piles are driven in the shape of a U when viewed from above. The system functions as a horizontally tied membrane relying solely on the vertical flat sheet pile anchor wall to retain a curved flat sheet pile arch face. The bulkhead becomes a series of U-shaped vertical member structures.
OCSP technology provides low cost and high performance. The system has been used effectively in locations that are susceptible to severe ice, soft soils, deep water, scour, and seismic events. The OCSP system provides high load capacity and requires minimal sheet pile toe embedment. It is easily modified for increased loading or unforeseen conditions and accommodates long-term settlement due to its flexible nature. The design provides cost savings for development in ordinary conditions and provides savings that are particularly evident in difficult environments (deep water, soft soils, etc.). The minimal cost of the structure is a result of a straightforward design, a simplified construction process, and low maintenance costs.