Sponsored by Geotechnical Engineering of “111” Intelligence Base for Intelligent Construction and Safety of Geotechnical and Underground Engineering in Southwest Jiaotong University (SWJTU), the Department of Geotechnical Engineering invited Professor Zhaohui (Joey) Yang, director of the Geotechnical and Permafrost Engineering Research Laboratory at the University of Alaska Anchorage, USA, to give two academic lectures related to geotechnical engineering on September 29, 2021. Before the lecture, Professor Yang Tao, dean of the Department of Geotechnical Engineering, expressed his welcome and thanks to Professor Yang on behalf of “111” Intelligence Base and the Department of Geotechnical Engineering, and gave a brief introduction to the contribution and future development made by geotechnical engineering in talents cultivation and national major engineering services.

Then, Professor Yang started his presentation titled “Geotechnical Challenges and Assessment of Perennial Permafrost Melting and Ground Settlement in the Arctic Region of Alaska under Climate Warming”. In the presentation, Professor Yang first analyzed the historical temperature change pattern in Alaska, proving the fact of global warming. Then he used different temperature prediction models to demonstrate the temperature change in the Alaska region in the next 80 years, and made predictions about six changes caused by climate warming in the Arctic region of Alaska, such as the time increase of frost-free period and the changing of intensity and distribution of precipitation. Based on those changes, Professor Yang gave examples of the geotechnical challenges encountered in Alaska where permafrost is widespread since climate warming. The challenges include differential settlement of building foundations, deep foundation damage in the permafrost layer, and differential settlement of highway roadbeds on the permafrost layer.

Later on, Professor Yang focused on how to assess the melting of permafrost under warming conditions and how to predict the ground settlement caused by thermal thawing of permafrost. Professor Yang’s wonderful presentation showed us the geotechnical engineering challenges brought about by the melting of permafrost in the Arctic region of Alaska. To cope with these challenges, he proposed three research needs that should be considered in future research: coupled hydrothermal models, permafrost thawing and sinking prediction, and risk assessment framework and response strategies for building structures in permafrost areas threatened by climate warming.

In the second presentation titled “Bridge Foundation Engineering in Seasonally Frozen Soil Area: Seismic Performance and Design”, Professor Yang firstly demonstrated his collections of a large number of seismic examples of medium bridge pile foundations in Alaska during historical earthquakes, which led to the special seismic weaknesses of medium bridge pile foundations in seasonally frozen soil zone during winter. The dynamic response of pile foundations under the two working conditions of liquefied and non-liquefied soil layers under the permafrost was systematically studied by means of field tests, such as indoor shake table tests and numerical simulations, revealing that under the effect of seismic load, the maximum bending moment position of the pile foundations under the seasonally frozen soil shifts upward and increases to some extent due to the high stiffness and strength of the surface permafrost. Finally, Professor Yang proposed seismic design solutions and ideas for bridge foundation engineering in seasonally frozen soil zone for this specific case, and the recommendations were incorporated into the bridge design manual of the State of Alaska Department of Transportation and Public Facilities.

After the lecture, experts, scholars and postgraduates from SWJTU and other related research institutes in China had an in-depth discussion with Professor Yang on the relevant issues mentioned in the presentations, and Professor Yang gave detailed answers to questions. At last, the participating teachers and students once again expressed their gratitude to Professor Yang for his wonderful lectures and hoped that they would have more opportunities to invite Professor Yang for more presentations in the future.

This lecture is the first one of the series of “Geotechnical Engineering of ‘111’ Intelligence Base for Intelligent Construction and Safety of Geotechnical and Underground Engineering”, which attracted more than 100 experts, scholars and postgraduates from SWJTU, related domestic institutions and research institutes. The lecture series broadened both teachers and students’ horizons and showed the efforts of SWJTU’s geotechnical engineering in pioneering, innovation, learning from others’ strengths and studying in a rigorous way. It helped open a new page for the school’s academic exchange and talent cultivation, and strongly promote the internationalization of School of Civil Engineering in SWJTU.

News Source: School of Civil Engineering