San Diego Courthouse Commons Shaft Shoring and Tunnel Canopy Tubes-Video

Video Transcription

Video Summary

Condon-Johnson installed temporary shaft shoring and canopy tubes for a 320-foot inmate-transfer tunnel beneath downtown San Diego, connecting the County Jail to the courthouse. The 60-foot-deep tunnel crossed streets and passed near the Old Jail, where existing footings and grade beams required additional grouting to limit settlement risk.<br /><br />The 18-by-52-foot shaft was supported by secant piles beside the jail and soldier beams and lagging on the remaining sides. Crews excavated in stages, installed three levels of internal bracing and a temporary truss, then constructed a reinforced 9,000-psi bottom slab. Limited access, live dewatering wells, and the need to maintain truck access complicated the work.<br /><br />Three reaches of canopy tubes were installed, their alignment checked with a gyro, and the tubes grouted. Monitoring and inspections found no settlements or collapses during construction. The presentation credited teamwork among the owner, contractor, and field crews as key to the project’s success.

Keywords

temporary shaft shoring

canopy tubes

inmate-transfer tunnel

secant piles

downtown San Diego