Highlighting links between Geology, index properties and mechanical behaviour at the beginning of a first course in Soil Mechanics

Abstract

The paper reports the experience of the authors teaching Soil Mechanics to undergraduate students. The focus is on the first three or four weeks of the semester. The practice consists of establishing, for the main soil archetypes (sedimentary sands and clays and residual soils), a strong relationship between: i) geological conditions prevailing during soil formation and thereafter; ii) soil physical-identification parameters; iii) basic trends of mechanical soil behaviour. The purpose is to explain - through simple mental models - how to interpret the basic physical and geological characterisation of the soil, in order to anticipate the main difficulties for a given (simple) project. These difficulties may include insufficient bearing capacity, very large and delayed settlements (soft clay), large settlements under seismic loading (loose sands), etc. In light of these difficulties, some solutions (just the main idea) are discussed (soil reinforcement, acceleration of settlements, vibro compaction, deep foundations instead of shallow foundations, etc.). The experience of transmitting this perspective is that these early classes enable: i) a better apprehension of the subsequent truly mechanical chapters; ii) a proper evaluation by the students of the technical and practical relevance of the subjects; iii) a strong motivation for the study of the discipline.