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RISK ANALYSIS AND OBSERVATIONAL METHODS IN PRACTICE: WHAT DO NEW CODES IMPROVE? (2011)
The construction of cuts, embankments and dam in and on different ground require the analyses of slope stability, deformations and often the use of the observational method. New codes, such as Eurocode 7 or its sister code in Switzerland SIA 267, prescribe the use of partial factors on friction angle and cohesion for slope stability analyses. This methodology has many shortcomings, as experienced in practice, in particular with steep slopes and irregular ground conditions. Examples with substantial deviation between analyses with the partial factors of safety and the global factor of safety will be presented. The use of the factor of safety on shear strength will be proposed, as had been used before in the limiting equilibrium methods, which is also called global factor of safety. The factor of safety on shear strength integrates the effects of shear strength, whether undrained shear strength, effective strength described by cohesion intercept and friction angle or curved envelopes; the effect of geometry and seepage and porewater pressures. With this approach stability analyses, deformation prediction and the observational method can be integrated this ultimately leads to safer construction.
ISGSR 2011 - Vogt, Schuppener, Straub & Bräu (eds) - © 2011 Bundesanstalt für Wasserbau
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