An International Railway owner/operator maintains a large through fill in the Northern Plains and over time the steep fill had sloughed and eroded. Railroad maintenance forces had installed retaining walls consisting of large stones retained by timber piles in the upper portion of the fill. Over time, those piles began to rotate and were weakened by grass fires in the area.
The only practical access to the fill site was over the tracks from either end. However, with clear track times averaging 15 minutes, traditional construction techniques such as drilled soil nails were not feasible. Moreover, any construction technique that would destabilize the track area during the construction process (like traditional drilled soil nails) would not be appropriate. GeoStabilization’s engineers designed an array of launched soil nails on either side of the tracks, which were then faced with reinforced shotcrete.
Launched soil nails have a reload time of approximately 90-120 seconds, which allowed multiple nails to be installed during the short track time windows. Additionally with no open hole drilling or waiting for grout to set up, launched nails immediately are able to accept load at their installation. This allowed the railroad operator to continue service on the track with no downtime or safety concerns during the construction process.
A variation of karst sinkhole grouting is the grouting of mined coal seams and workings located below existing infrastructure that exhibit the potential to propagate to the surface and cause sinkholes and/or subsidence.