Project Manager:
Yasser Korany, Ph.D., P.Eng., P.E., LEED AP, PMP
Technical Experts Involved:
Yasser Korany, Ph.D., P.Eng, P.E., LEED AP
Adam Lohonyai, M.Eng., P.Eng.
Incident Description
A masonry foundation wall in a semi-detached house collapsed suddenly during a basement underpinning project, causing severe structural damage to the nearly 100-year old building. Origin and Cause Inc. was retained to design emergency stabilization measures to ensure the safety of the public and to investigate and determine the cause of the collapse.
Investigation
After stabilizing the structure, a detailed visual examination of the affected unit was carried out. Permit drawings for the underpinning project were carefully reviewed and compared with the actual site conditions. The contractor and structural engineer working on the underpinning project were also interviewed to obtain further information about the progress of the project.
Cause of Loss
Origin and Cause Inc. determined that the affected foundation wall ultimately collapsed because the underpinning project had not been executed properly. The foundation wall bracing had not been properly designed to prevent inward movement at the base, the length of the undermined portion of the footing exceeded the maximum length recommended by the geotechnical engineer that had been consulted on the project, and temporary vertical shoring to carry the weight of the floors above had not been installed.
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