Project Summary/Scope:
In 2014, a condominium was constructed in Boston, but found to be right in front of a rock slope that had some structural deficiencies. Engineers were sent to evaluate the stability of the rock slope and create a remediation plan. A LiDAR survey was used to determine the cross-section of the rock slope, and to identify any wedge, planar, or toppling modes present within the mass. It was determined that there were multiple potential modes of failure present, and the bedrock within the rock slope had undergone significant weakening and loosening over time. Rockfall analysis provided the engineers with an idea of how the rock face would perform over time, and where the discontinuities would give way to failures, and what they would result in. At the base of the rock slope was a fence, which was installed previously. It was determined that this fence was inadequate by itself to stop rock falls from spilling into people’s backyards and impacting their homes, and without the fence being there, that would have occurred already.
The findings were then followed by recommendations for slope stabilizing measures, like the installation of rock dowels, anchored wire mesh, anchored drapes to catch rockfalls, and scaling. These proposed ideas were put before the owners of the condominium, agreed upon, and implemented in 2016.
Complementary Technologies Used:
LiDAR surveying
Alternate Technologies: The alternative solutions proposed included scaling, mechanical stabilization, anchored wire mesh, passive drape,
catchment barrier, and buttressing. These solutions were ruled out based on the size of rocks predicted to break off and fall from the slope.
Additional Photo:
Additional Photo or Drawing:
TBD
Performance Monitoring:
TBD
Cost Information:
TBD
Case History Author/Submitter:
Andrew R. Blaisdell, P.E., M.ASCE
GZA GeoEnvironmental, Inc., 477 Congress St., Suite 700, Portland, ME 04101.
E-mail: andrew.blaisdell@gza.com
Project Technical Paper:
Blaisdell, Andrew & Snow, Christopher & Vetere, Frank. (2018). Rock Slope Stabilization Evaluation, Design and Construction Greater Boston, Massachusetts. 330-344. 10.1061/9780784481622.026.
Date Case History Prepared:
January 2021