PROFESSOR SERGE Leroueil presented the 39th Rankine Lecture, 'Cuts and natural slopes - a geotechnical perspective', in London last month.
Leroueil, of Laval University in Quebec, used the prestigious Rankine platform to discuss the mechanism of slope failures, based largely on his experience of soft clays in Canada.
Leroueil singled out viscosity, fatigue, partial saturation and progressive failure as significant and not fully understood factors in governing the behaviour of slopes.
In particular he highlighted the concept of fatigue to explain how slopes can stand up through periods of extreme rainfall (and high pore pressures) but then fail shortly afterwards in a period of normal weather. 'It is accepted in other branches of mechanics and material science' but is not really accounted for in soil behaviour, he said.
In giving the vote of thanks Professor Dick Chandler of Imperial College described Leroueil's presentation as a valuable review of landslide mechanisms, adding: 'His work on the behaviour of natural heavily structured soft clays has implications beyond Canada.'
The lecture was followed by the Rankine dinner, attended by 370, including a number of former Rankine lecturers, at which it was announced that Professor John Atkinson of City University will present next year's lecture.