ABSTRACT
In geotechnical engineering there are numerous sources of vague, imprecisely defined boundaries and subjective data. Conventionally, in the construction of the mathematical models in limit states design, these uncertain data are treated as random variables. Probability theory is viewed as the unique methodology to handle uncertainty in limit states analysis. But in geotechnical engineering, data and associated rules (geological maps, sampling, field tests, modes of failure, elasticity and plasticity theories, static and kinematics models…) are connected with fuzzy, dubious and to a great extent non-statistical data. In addition, there is impreciseness in the definition of system performance and failure events. That is, in the geotechnics, probability theory can not be considered as the only appropriate methodology in the limit states design.
The utilization of fuzzy logic provides a technique for the estimation of uncertainty in geotechnical structural analysis. Within the limit states design, this means that the risk of failure is not a crisp failure event but rather a fuzzy failure event. The environmental parameters are thus rendered into fuzzy variable, and the structural reliability is characterized by fuzziness.
In this paper, the application of fuzzy logic concepts within the framework of limit states analysis will be introduced. Further, disadvantages and difficulties of the conventional stochastic methods will be epitomised. Numerical examples illustrating this approach will be dealt with especially with reference to the European Code of practice EC 7.
