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Reactivation of a deep-seated ancient landslide Incorporation of designed structure into slide mitigation Extremely cost effective The Washington Park Station of the Westside Light Rail Project was constructed on a deep-seated ancient landslide. Initial excavation for the station headhouse reactivated the ancient shear plane of the landslide. Excavation was temporarily halted after Landslide Technology determined that a local slope failure would likely occur during continued excavation. In association with the firm of Parsons Brinckerhoff Quade & Douglas, Landslide Technology performed an investigation of the reactivated ancient landslide and conceived an imaginative solution to provide resistance against sliding at a very low cost. Piles that were initially designed as the foundation support for the station headhouse were modified to resist the lateral forces of the deep landslide. A line of piles on the uphill side of the excavation was redesigned as heavily reinforced concrete shear piles. A landslide monitoring system was designed, installed and implemented by Landslide Technology to closely monitor the reactivated ground movement and to allow construction to continue. In addition, Landslide Technology developed a long-term landslide monitoring plan using the automatic data acquisition system of in-place inclinometers, multiple-level piezometers and a rain gauge. The automated system allowed a critical “threshold movement rate” to be established in the event of reactivated ground movements. This landslide remediation won the Project of the Year Award in ACEC Oregon Engineering Excellence competition. |
