Solution for Existing Foundations built on Weathered Rock-Lateral Restraint with Drilled Micropiles-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes temporary support solutions used during rehabilitation of the Henry Hudson Bridge’s southern approach (Project HH-88B). The work addressed concrete damage caused by alkali-silica reaction (ASR), while requiring five lanes of traffic to remain open throughout construction.<br /><br />The site posed significant challenges, including extensive excavation and structural support needs, limited headroom, congestion, and complex construction conditions. The original excavation support system included micropiles and timber lagging, as well as internally braced supports and rock anchors.<br /><br />During construction, weathered bedrock was encountered as an unforeseen condition, affecting the planned lateral support of the excavation. The presentation focuses on the resulting solution: providing lateral restraint to the weathered rock using drilled micropiles. Design and analysis materials included DeepEx software, along with additional assessment of excavation and structural support requirements.<br /><br />The project involved a multidisciplinary team led by the Metropolitan Transportation Authority and included engineering, construction, demolition, and specialty foundation firms.

Keywords

Henry Hudson Bridge

Project HH-88B

temporary support

alkali-silica reaction

micropiles

excavation support

weathered bedrock

lateral restraint

bridge rehabilitation

DeepEx software