Application of fuzzy set theory in evaluation of soil collapse potential

Collapsible soils have considerable strength and stiffness in their dry natural state but settle dramatically when they become wet. This paper documents a low-cost, qualitative evaluation scheme using fuzzy set analysis to determine regional collapsibility based on subjective knowledge of the geological and geotechnical conditions and their uncertainty. The geological and geotechnical factors and their category were defined based on relevant literature. Each factor and category was then weighted or rated using linguistic terms developed from expert assessment. The linguistic data or information obtained from the assessments was represented and processed using fuzzy sets. To assess the criteria, 87 collapse potential tests were performed on undisturbed soil samples gathered from 27 different locations throughout Iran. It is shown that the geotechnical criteria predict soil collapsibility much better than the geological criteria