时间：2012年9月7日（周五）下午15：30

地点：岩土楼203

Professor David Toll

School of Engineering and Computing Sciences

Durham University, UK

    Abstract: The lecture will discuss advances in measuring and controlling suction in unsaturated soils. Devices for measuring water content will also be considered. Significant advances in unsaturated soils testing have been gained through the development of high suction tensiometers allowing direct measurement of suction beyond 100kPa. This has allowed the implementation of techniques that measure and control suction directly, where the soil is tested in the same conditions as in nature. Previously, much reliance had been placed on indirect measurements of suction and on control of suction using the axis translation technique. It is argued that this technique should be avoided as the use of an elevated air pressure does not replicate natural conditions. The lecture will present advances resulting from the use of high suction tensiometers for laboratory testing. An automated suction control system using the air circulation method will also be described that can impose controlled cycles of drying and wetting. For water content measurement, advances in the use of TDR and electrical resistivity will be discussed.

    Biodata: Professor David Toll has been carrying out research into unsaturated soils for 30 years. He was one of the first to set out a critical state framework for unsaturated soils in 1990. He has published extensively on the shear strength and volume change behaviour of unsaturated soils. The application of his research is primarily in rainfall-induced landslides and the impacts of climate change on slopes. He is a member of the ISSMGE Technical Committee TC106 on Unsaturated Soils and is also Chair of Joint Technical Committee JTC2 on Representation of Geo-Engineering Data in Electronic Form. He has been an organisor of Conferences on Unsaturated Soils and Information Technology in both Asia and Europe. Dr Toll has held Visiting Professor or Research Fellow posts at National University of Singapore, Nanyang Technological University, University of Western Australia and University of Newcastle, Australia. Professor Toll was founding editor of the international journal Geotechnical & Geological Engineering and is a member of editorial boards for the Quarterly Journal of Engineering Geology and Hydrogeology and Géotechnique Symposia in Print.