At the invitation of IRSM, Professor YAO Yangping from Beihang University (BUAA) attends academic forum and delivers a report on Dec 20. The forum is hosted by Director FENG Xiating from State Key Laboratory of Geomnechanics and Geotechnical Engineering (SKLGME).

With the topics of Generalized Nonlinear Strength Theory (GNST) and Unified Hardening Model (UN model), Professor YAO introduces the latest research achievements and progress. GNST includes a series of single nonlinear strength theories which have already existed and might appear in the future. A unified expression describing the nonlinear characteristics of strengths of various materials on the π plane and the meridian plane is used in the GNST, thus a brand new system of the nonlinear strength theory is formed.

The over-consolidated unified hardening model (UH model) proposed by Yao can describe many characteristics of clays well, including stress-strain relationships, stress dilatancy, strain hardening and softening, and path dependency behavior. The strain-hardening, softening and dilatancy behavior of overconsolidated clays at a given temperature can be described using the UN model considering temperature effect; the volume change behavior caused by heating can also be predicted. Compared with the modified Cam-clay model, the new model requires only one additional parameter to consider the behavior of the decrease of preconsolidation pressure with an increase of temperature.Professor YAO have discussion with researchers after his report, he also visits laboratory of IRSM.

　　YAO Yangping is the professor of Beihang University, Chief Scientist of 973 Plan; he is also the member of many societies including Chinese Society for Rock Mechanics and Engineering, and Chinese Society of Theoretical and Applied Mechanics. Yao works as editor of professional journals at home and abroad. He proposes TS method and UH model.