报告题目：颗粒材料质量损失及其联系熵对力学特性影响
Title: Mechanical consequences of mass loss in granular materials and contact entropy
报 告 人：Dr. Daniel Barreto/Edinburgh Napier University
报告时间：2013年5月17日 14：00-16：00
报告地点：紫金港校区安中大楼B328
欢迎有兴趣的老师和学生参加！
报告简介
Mass loss phenomena are observed in multiple geotechnical applications including (i) landfill analysis – due to biodegradation of material; (ii) internal erosion in dams and (iii) settlement due to dissolution of gypsiferous deposits. Experimental work using sand-salt mixtures has been carried out to quantify and understand the mechanical consequences of mass loss. In an extensive set of oedometric and triaxial tests, the effects of confining stress, initial density as well as amount and size of soluble materials have been assessed. It has been found that the effects of both the amount and size of soluble particles are the most significant in terms of volumetric behaviour and stress-strain response. An additional effort has been made to quantify these effects. As a consequence, a new parameter dependent on the change of both the void and solid phase changes during dissolution together with the concept of grading entropy has been used to successfully interpret the experimental tests.
In parallel to the experimental tests, a set of DEM simulations that replicate the physical experiments have been performed to gain further insight on the micro-scale interactions underlying the observed macro-scale response. It has been confirmed through these simulations that the observed experimental results can be explained in terms of the evolution of strong force chains that carry most of the stress within the granular material and their interaction with the soluble particles.
In this talk the experimental findings and their interpretation will be presented followed by a sample of the DEM results, making emphasis on the findings that help to explain the fundamental mechanisms. The final part of the talk will present for the first time the concept of contact entropy, which is an extension of the grading entropy used for the dissolution tests, but in this case applied to the analysis of DEM simulations under generalised stress conditions. It is proposed that the concept of contact entropy can be used instead of conventional DEM analysis tools for a better understanding of the anisotropic behaviour of granular materials.
报告人简介
Dr Barreto has over 9 years work experience in Geotechnical Engineering including analysis and design of foundations for marine structures, bridges, embankments, retaining structures and pavements. He also has significant experience in slope stability assessments, ground investigation and soil laboratory testing.
Daniel has a very strong academic background, including 5 years (MSc & PhD) of experimental and numerical research on the behaviour of granular materials at Imperial College London. He is an expert in the use of the Distinct Element Method (DEM) in Geotechnical Engineering and his main research interests are related to the effects of soil fabric and structure on soil behaviour under generalised (3D) conditions. Examples of current research projects he is involved with include (i) experimental and numerical studies on the mechanical changes due to mass loss in soils; (ii) experimental research on the behaviour of peat and (iii) numerical research using DEM to gain further understanding of various geotechnical problems.
Being a Lecturer at Edinburgh Napier University since 2009, Dr Barreto has also pursued research interests in the area of technology-enhanced learning. He teaches various subjects in Geotechnical Engineering at both undergraduate and postgraduate level including topics such as consolidation, shear strength, slope stability, bearing capacity and design of foundations according to Eurocode 7.
He has presented his work at various workshops, conferences and symposia and has delivered some invited talks at different universities in the UK and abroad. He is the author of several journal and conference papers and has been a reviewer for geotechnical journals such as Geotechnique, the Canadian Geotechnical Journal, Computers & Geotechnics and Particuology. On the educational/learning side he has also reviewed papers for the European Journal on Engineering Education and the ICE Proceedings.
浙江大学交通工程研究所
省岩土力学与工程学会岩土本构 理论与数值分析专业委员会