Performance of Utility‐Trench Shoring: Case Study

Numerous workers are injured or killed each year due to trench caveins. The cause of death in many cases is due to suffocation or the force of the cavein, which causes a crushing injury to the chest. Utility‐trench excavations frequently have little money available for subsurface exploration, and the trenches extend over long distances. Because of these factors, there are more opportunities for cave‐ins in utility trenching. The paper describes a case history dealing with the collapse of utility‐trench shoring. There were two lessons learned from this case history. The first was the presence of a parallel storm drain surrounded by sand backfill that was categorized as running soil. Loss of support from the storm‐drain backfill allowed the shoring uprights to slide downward. The second lesson was that the shoring uprights did not extend all the way to the bottom of the trench. If they had, they would not have been able to slide downward and cause the collapse of the shoring system.