Repairing Railway Spur Roadbed Failure Using Geotextile-Encased Columns (05-0881)**
Richard Donovan Short, Kleinfelder, Inc.
Yogesh Prashar, Kleinfelder, Inc.

When a rail bed failure occurs over soft weak soils the repair options are limited to ground improvement techniques or a deep foundation support system. The geotextile encased column method is a new method of embankment support that minimizes post installation settlement as well as reducing the waiting period after installation and before the application of load. The method was developed in Europe for support of high speed rail systems being constructed over compressible peat deposits. Kleinfelder used the GEC method to repair the failure of a rail spur line located on fill over Bay mud in Oakland California. The method consists of an array of closely spaced rock columns installed through a soft weak soil layer. The rock columns are wrapped in a geotextile sock forming a uniformly shaped column. The columns are installed using a steel pipe casing fitted with a trap door on the bottom. The array of rock columns is covered with a layer of geogrid and 24 inches (61mm) of aggregate base to form the rail bed. A load test was performed to measure settlement. It was concluded that the GEC’s are less costly than other methods such as deep mixing or augercast piles with pedestals, GEC’s can be loaded immediately saving delays for curing or preloading, and GEC’s reduce the post installation settlement compared to stone columns.