Nicholson in the Neighborhood: Virginia's North Hill Project-PPT Presentation

PPT Presentation

Pdf Summary

The North Hill project transformed a 33-acre former mobile-home site near Alexandria, Virginia, where slope instability and ground movement had made development difficult. The site was divided between multifamily housing and townhomes, with retaining walls needed to create usable land while preserving a planned park and limiting disturbance to wooded areas.<br /><br />Subsurface conditions were highly variable, including plastic clays, silts, sands, groundwater, and potentially slickensided soils. Previous erosion and movement complicated the definition of soil properties. Design requirements included global stability factors of safety of at least 1.25, a maximum wall-top movement of 2 inches, and a block-style architectural finish.<br /><br />The project used large-diameter drilled soldier piles and high-capacity strand anchors, with bond zones extending beyond deep failure surfaces. The multifamily wall was about 800 feet long and up to 15 feet high, with one anchor row in anchored sections. The townhome wall was about 1,000 feet long and up to 40 feet high, with as many as three anchor rows.<br /><br />Construction encountered collapsing drill holes, perched water, and running sands. Crews adapted from open-hole drilling to temporary and segmental casing, and adjusted methods for setting soldier-pile beams. Anchors were drilled, grouted, and post-grouted; every anchor received a proof test, with additional performance and creep testing. A specialized subcontractor installed the architectural shotcrete face.<br /><br />The presentation emphasizes the importance of safe working platforms, adapting construction methods to changing ground conditions, and quality control. It includes wall-movement material but provides no numerical performance results in the supplied text.

Keywords

North Hill project

Alexandria Virginia

retaining walls

slope instability

ground movement

drilled soldier piles

strand anchors

global stability

shotcrete face

perched water