Determination of partial factors for the verification of the bearing capacity of shallow foundations under open channels

Abstract

The limit state design method has been introduced into the design criteria for geotechnical structures. The current paper attempts to apply the reliability-based design method, at Level II, to the bearing capacity of the foundations of open channels from the viewpoint of the limit state design. To examine the applicability of the proposed procedure for practical structures, the reliability index is computed for evaluating the stability of the foundations of existing open channels designed by the conventional method. The conventional design procedure makes excessively safe side design. We applied the FORM to the existing open channels designed by the conventional design procedure, and consequently, large values of reliability index, 3 and 5 were obtained for clayey and sandy soils, respectively. Finally, the partial factors for the soil parameters have been determined, corresponding to the target reliability indices β _t =1, 3 and 4.

Keywords:

• open channel
• bearing capacity
• limit state design
• first order reliability methods (FORM)
• reliability index
• statistical property of soil parameters
• foundations
• geotechnical reliability
• reliability analysis

Acknowledgements

The authors are grateful to Mrs Hitoshi Yano and Taro Seto of Japanese Ministry of Agriculture, Forestry and Fisheries, and its Tokai Branch for their help in collecting the data and providing some arrangements and suggestions. The members of performance-based design committee of the Japanese Institute of Irrigation and Drainage are also acknowledged for their discussion.