Stabilization of the Historic Morton Street Bulkhead-PPT Presentation

PPT Presentation

Pdf Summary

The 145-year-old Hudson River bulkhead, built between 1873 and 1877, had experienced ongoing lateral movement and settlement. Earlier repairs—including relieving piles and riprap—had not stopped movement. Investigations in 2014 combined surveys, ground-penetrating radar, pavement coring, inspections, movement monitoring, and stability analyses. Findings included gaps of up to 8.9 cm behind the bulkhead, voids beneath the pavement, and movement rates of 0.25–1.8 cm per year.<br /><br />Geotechnical analyses identified the Type B section, with its steeper glacial-sand slope, as particularly vulnerable. The team designed a stabilization system of 46 pile-and-tieback pairs, arranged to limit required workspace, avoid work outboard of the bulkhead, and reduce conflicts with existing piles.<br /><br />Marine construction took place from April 2017 through December 2018. Low-vibration drilling was used to install the piles, while sonic drilling installed the soil anchors with minimal soil disturbance and no spoils. Tiebacks were tested and stressed in a carefully planned sequence.<br /><br />Automated monitoring tracked bulkhead and ground movement during construction. Maximum lateral movement measured by inclinometers was 28 mm. Data also revealed deep-seated movement to 24.3 m below ground, supporting the conclusion that soft-organic-soil slope creep contributed to the problem. Movement stabilized following construction.<br /><br />The project’s success relied on a tailored design, careful sequencing, and construction methods that minimized vibration and disturbance while accommodating the historic structure.

Keywords

Hudson River bulkhead

lateral movement

geotechnical analysis

stabilization system

pile-and-tieback

soil anchors

sonic drilling

inclinometer monitoring

historic structure

slope creep