主讲人：Peijun Guo 教授

邀请人：宫全美 教授

时间：2023年12月12日（周二）上午9:00-11:00

地点：通达馆103会议室

主讲人简介：

Dr. Peijun Guo is Professor in the Department of Civil Engineering at McMaster University. Dr. Guo has extensive experience in experimental study of soil behaviour, numerical modelling of complex geotechnical structures, seismic soil-structure interaction, and the development of stress-strain models that account for the effects of stress level, density and internal structure on mechanical properties of geological materials. He has published more than 100 publications in international refereed journals (SCI). More recently, his research interests have been extended to multi-scale and multi-physics coupled problems in geotechnical and geo-environmental engineering to account for the impact of environmental factors related to climate change. His research on applied technology includes seasonal response of geotechnical structure in permafrost, seismic responses of deeply buried structures considering soil-structural interaction. He has received research funds from various grant agencies (including NSERC, CFI, OIT and MITACS) and industry.

主讲内容简介：

The fast development of high-speed railway network causes new challenges in geotechniques owing to the high frequency, low (displacement) intensity vibration superposed to geotechnical structures, including the embankment and subbase. An experimental study has revealed shear resistance reduction and additional volume change of granular soils caused by high-frequency, low intensity vibration. In contrast to the liquefaction of sand that is attributed to a decrease of effective stress induced by an excess pore pressure in saturated sand under undrained conditions, vibration-induced shear resistance reduction is related to the internal structural change in vibrating granular media. In extreme cases, it may lead to natural hazards, such as the triggering of landslides during earthquakes, the initiation of avalanches, and even long-runout landslides of dry soil on the moon and Mars. Vibration-induced shear resistance reduction in granular “fault gauges” is believed to be a potential mechanism for the dynamic triggering of earthquakes in geophysics. On the positive side, vibrational techniques have been used in geotechnical engineering when installing piles in sandy soils since the pile's vibration significantly reduces both shaft and toe resistance. Nevertheless, the lack of a fundamental understanding makes it difficult to handle the coupling of high-frequency vibration and quasi-static loading. A theoretical framework is recently developed by extending the energy-based rate process theory and the concept of shear-transformation-zone theory to describe this phenomenon involving simultaneous vibration and quasi-static loading with different characteristic time scales. The framework is expected to provide new tools for the analysis of geotechnical problems related high-speed rails and underground transportation systems.

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