ASCE has honored Ning Lu, Ph.D., F.EMI, F.ASCE, with the 2017 Ralph B. Peck Award for his multiyear case study monitoring the subsurface hydrological and mechanical conditions leading to landslide occurrence on the coastal bluffs between Seattle and Everett, WA, and for using the data collected to develop a new hydromechanical framework for slope-stability analysis.
Lu’s research over the past decade has made significant contributions to the subject of rainfall-induced landsliding. Of particular note is his effort on a field investigation and corresponding case history that began in 2000 to determine the hydrologic conditions leading to landslide occurrence along a stretch of steep coastal bluffs located near Seattle. This location is a source of recurring landslide hazards and is a major concern to Burlington Northern Santa Fe Railway and Sound Transit, which operates a railway along the toe of the bluffs.
In January 2006, a slide occurred at Lu’s research site near Edmonds, WA, which had been fully instrumented to monitor weather, infiltration, positive and negative pore pressures, and associated slope displacements. Capturing such measurements during an actual slide-triggering event, most notably including direct and continuous measurements of soil suction, is a rare occurrence.
This effort provided unique data on rainfall-induced landslide initiation and some of the first direct quantitative evidence showing that slope failures can in fact occur under unsaturated soil conditions. Subsequent analysis of the case history showed that the timing and depth of the landslide could be reconciled within a unified effective stress framework for variably saturated soil that had been developed previously by Lu, and which was recognized with the ASCE Norman Medal. Results from the case history are currently being used to develop a comprehensive hazard mitigation strategy for the railway. The study is coming full-circle from measurement, to analysis, to recommended practice.
The Ralph B. Peck Award is presented for outstanding contributions to the geotechnical engineering profession through the publication of a thoughtful, carefully researched case history or histories, or the publication of recommended practices or design methodologies based on the evaluation of case histories.