Design and Construction of Driven H-Piles for Landslide Stabilization in Marlboro Clay Formation-Paper

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Heavy rainfall in May 2014 triggered a major landslide along Piscataway Drive in Fort Washington, Maryland. Ground movement damaged a 450-foot section of roadway, broke utility lines, and threatened nearby homes, prompting evacuation of 28 residences. The site is underlain by Marlboro Clay, a landslide-prone formation between permeable sand deposits. Investigations found critical failure surfaces at the sand–clay interface and within the clay, generally 20–36 feet below ground, with some shallower failures along the hillside.<br /><br />The team combined borings, laboratory and in-situ testing, inclinometer monitoring, slope-stability analyses, and lateral pile analyses to evaluate remedial options. Driven steel H-piles were selected to address cost, environmental considerations, property and utility constraints, and the need for rapid construction. Design analyses treated soil above the failure surface as providing no resistance and relied on soil below it for lateral support.<br /><br />The final stabilization used 410 HP16x141 piles arranged in two or three rows along the roadway and hillside toe. Piles were driven 60–70 feet deep, at 5–7-foot spacing, with 35–50 feet of embedment below anticipated slip surfaces. The design targeted a long-term slope factor of safety of 1.3; predicted pile deflections were generally 0.75–1 inch, with a maximum below 2 inches.<br /><br />Ground movements were monitored during and after construction. Post-construction readings showed no significant movement in the stabilized or adjacent areas, supporting the effectiveness of the driven-pile approach for this deep-seated landslide.

Keywords

landslide

Marlboro Clay

Fort Washington Maryland

Piscataway Drive

heavy rainfall

slope stabilization

driven steel H-piles

roadway damage

inclinometer monitoring

slope stability analysis