Characterization of the mechanical response of fine-grained soils for earthquake engineering practice

点击翻译按钮获取中文摘要

Liquefaction of soil has caused severe damage to structures and lifelines during past earthquakes, and has led to loss of life and disruptions to living and working conditions of citizens. The Metro Vancouver Region of British Columbia (BC) is located in a zone of high seismicity, and it has been reported that the damage costs from a major earthquake in Vancouver could be as high as $75 billion. Saturated fine-grained soils (e.g., silts) are commonly found in natural river deposits and also originate as a waste product in tailings derived from the mining industry. Recent earthquake experience suggests that liquefaction of natural silts is a concern; it is also known that densification of silt to mitigate liquefaction is more expensive than the methods required for sands. Much of the current research focus has been on the liquefaction of sands whereas the seismic behaviour of low-plastic fine-grained silts has been investigated only on a limited scale. There is strong evidence that silt behavior is complex and not well understood, and there is a need to develop robust approaches for silt liquefaction assessment for safe and cost-effective designs. This requires advancing the knowledge on the mechanics of silts under seismic shaking and investigating the effects of the key physical factors on the behaviour of silts. With this impetus, systematic experimental research will be undertaken to study the fine-grained soils through the following focused themes: (i) Cyclic shear response of sand-silt and silt-clay Mixtures; (ii) Effect of vibro-replacement on the response of silts; and (iii) Particle structure of silts. The research will generate a comprehensive database for silt behaviour useful for improving the numerical models predicting earthquake-induced geotechnical hazards. The work will develop practice guidelines with robust approaches to assess liquefaction of silts, advance the laboratory technology for testing of silts, and develop new methods for assessing the effectiveness of the measures taken to improve silts against liquefaction. The use of modern imaging technologies to study the particle structure of silts will provide new insight to supplement the conventional seismic design approaches in a novel way. The results will be of global significance to geotechnical design in earthquake-prone silt-soil areas, and especially with respect to enhancing the seismic safety of Canadians. With the knowledge gaps bridged, the work will contribute to developing novel methods with particular applicability to civil and mining engineering. Three masters and four doctoral students will be trained, thus adding to the earthquake engineering expertise in Canada. With the high quality of training received, the students entering the workforce will possess a high employability.