Project: Kansas City Southern Rail Road
Location: Robstown, TX
Asset: Mainline and sidings over a large concrete box culvert (replacing a former mainline bridge)
CHALLENGE
A large concrete box culvert was installed to replace a mainline bridge when two new sidings were constructed. Approximately 15 feet on each side of the new culvert was backfilled with locally available clay soil placed without adequate compaction. Settlement of the improperly placed backfill began soon after the project was completed and continued until it reached about 5 inches on one side and 6 inches on the other, significantly affecting railroad operations and requiring frequent maintenance.
SOLUTION
Superior densified the improperly placed clay backfill in place, injecting grout under pressure to tighten the loose soil (compaction grouting). Grout was injected at 26 locations on each side of the culvert, in a triangular pattern with approximately 7 feet of spacing between points. Injection was performed both under and on both sides of the existing mainline and sidings. The area outside the existing track bed was also remediated to allow for future siding construction.
RESULTS
The improperly compacted clay backfill was densified in place.
Work was completed in the spring of 2014. Settlement stopped, and the area has required only routine maintenance since then.
The subgrade outside the track bed was also improved, preparing the area for future siding construction.
