The Job
This rail bridge pier stabilization project is located adjacent to the Congaree National Park. This project was a capital repair to a bridge pier for a Class I railroad. The rail line serves the Port of Charleston, SC.
The Challenge
The Congaree River south east of Columbia, South Carolina frequently sees high flow events, inundating the surrounding low country. At the transition from timber trestle to a bridge, the first bridge pier was originally constructed of stone. The pier bears on a timber mat with timber pile supports. Over time, the river channel migrated and began to expose the timber substructure and scour below the pier.
The nearest road was more than four miles away through impassible swamp. So, all work had to be performed from the river. All material had to be pumped across the bridge, a distance of approximately 600 feet. Due to the compressive nature of the underlying materials, any backfill material needed to be as light as possible. But, due to the high likelihood of flooding, couldn’t contribute significant potential uplift.
The Solution
To address the scour, minimize additional load to the underlying soils, and ensure long term stability of the structure, a third party consultant designed a two tier sheet pile jacket for the structure. They specified the backfill material as 65lb/cuft cellular concrete for the lower segment. And, approximately 45lb/cuft cellular concrete for the upper segment.
CJGeo designed mixes which would meet these requirements:
- be pumpable 600LF,
- tolerate the high vibration environment from the more than 12 trains per day, and
- facilitate a short installation timeframe.
After the general contractor installed the first level of sheet piling and dewatered the area, CJGeo placed approximately 150CY of 65lb/cuft CJFill-Under Water material. Next came installation of the second, smaller diameter sheeting ring. CJGeo then filled the annular space between it and the necked down pier with 45lb/cuft CJFill-Standard material.
CJGeo generated and placed all of the CJFill low density controlled low strength material over a period of four days onsite.
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Facing a similar challenge to this bridge pier stabilization project? Give us a shout or shoot us a text. Click the state marker for the location of your project for contact info for the appropriate rep.
