Forensic Analysis of an Excavation Bracing System Failure
by Daniel C. Brahana, P.E., M.ASCE, (ABE Enterprises, Inc., 1925 Vaughn Road, Suite 110, Kennesaw, Georgia 30144), William M. Tanner, P.E., A.M.ASCE, (ABE Enterprises, Inc., 1925 Vaughn Road, Suite 110, Kennesaw, Georgia 30144), Larry D. Mullins, P.E., M.ASCE, (GeoSystems Engineering, Inc., 570 Colonial Park Drive, Suite 312, Roswell, Georgia), and Cameron Troxel, A.M.ASCE, (GeoSystems Engineering, Inc., 570 Colonial Park Drive, Suite 312, Roswell, Georgia)
Section: Reliability Problems in Geotechnical Engineering, pp. 2032-2041, (doi: http://dx.doi.org/10.1061/41095(365)206)
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| Document type: |
Conference Proceeding Paper |
| Part of: |
GeoFlorida 2010: Advances in Analysis, Modeling & Design |
| Abstract: |
This paper presents a case study of the failure of an excavation shoring (bracing) system with a sloping backfill. The initial stages of the failure were detected by a continuous automated monitoring system. Early detection allowed remedial measures to be implemented to minimize the effects of the failure and restore stability to the slope. An evaluation of the site conditions after the failure concludes that the failure mechanism was related to slickensides present within the weathered rock and rock matrix. Prior to the failure, the slickensides were undetected by previous design geotechnical studies completed by the project geotechnical engineer or preliminary observations of the excavation. Geotechnical and construction conditions that led to the failure are examined as well as an analysis of the failure using reliability methods. The results of the analysis considering the presence of slickensides are compared with the results of the analysis with the absence of slickensides. This enabled the authors to estimate the probability of failure in either case and make a comparison as to the likely cause. |
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