GeoStabilization International® was asked to look at an urgent situation above a national railway operator’s switching yard, which was on the edge of the roadway of a key route in the area. The affected area was supported by gabion baskets above a highly fractured rock substrate 100 feet above the railroad yard. This support issue jeopardized 80 linear feet of the roadway.
GeoStabilization’s engineers performed site investigation utilizing rope access techniques due to the site’s limited accessibility. Measurements and photographs were taken from various vantage points, and Dr. Skip Watts (Radford University) and Dr. Brendan Fisher (Fisher & Strickler Rock Engineering) were consulted for additional repair options. All data collected was used to produce field sketches, then developed into an estimate, and eventually to perform global stability modeling to verify the field observations and initial conceptual design approach. A firm price proposal was submitted in 2011 and was funded by the railroad in 2012.
During the repair, GeoStabilization provided road traffic control while the railroad handled coordination with train traffic. The work included installing multiple rows of various lengths of grouted Self-Drilling SuperNails® installed through the gabion baskets for the entire length. Bedrock was encountered beyond the gabion baskets. Despite multiple time delays for trains over a two-week period, the project was invoiced at the proposed firm price amount.
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.