Experimental Micromechanical Study on the Influence of Environment-soil and Fluid-soil Interactions at the Grain Contact Interfaces

Description

The behaviour of unsaturated soils in the presence of wetting/drying cycles, which alter the saturation and stress states of the ground, has attracted significant amount of research by geotechnical engineers. In Hong Kong and many other regions with tropical/subtropical climate, heavy rainfalls and seasonal changes of the groundwater level have resulted in landslide failures and the instability of buildings/infrastructures, which, combined with the presence of variously weathered soil profiles, has triggered the interest by the geomechanics community to look into the problem of soil-environment interaction because of the uncountable losses of life and social/economic problems encountered. It is also well accepted today that soil behaviour may be significantly influenced by oxidation and development of iron-oxide coating in natural deposits. Iron-oxide coating has also triggered the interest by engineers/scientists not only on the point of view of a natural-environmental process, but it has also been used in recent years to prevent ground pollution/soil contamination. Soil coating, water-soil interaction and, in a broader sense, fluid-soil interaction have been topics of major interest as well by soil scientists and petroleum engineers since, for example, hydraulic fracturing in petroleum extraction encounters soil-rock interactions in the presence of fluids/lubricants of various viscosities. Despite the realisation by the scientific community that understanding of the complex problems involving soil-environment interaction and the improvement of our predictive tools in the safe and sustainable design of infrastructures and utilisation of resources necessitate a better understanding of the behaviour at the grain-scale and the interactions of soil grain and grain-rock contacts, there has been relatively limited amount of work investigating these problems at the fundamental level of grain interfaces in the laboratory. This project will look into the problem of soil-environment interaction at the grain scale/grain interfaces by performing an original research with cutting-edge laboratory facilities and methods, and provide new insights into various problems of major interests in Hong Kong and internationally. The major points of focus of this project are: (i) The micromechanical behaviour of variously weathered soils/rocks in the presence of wetting/drying cycles and changes in the saturation state (ii) The behaviour of iron-oxide coated grains and (iii) The interactions of soil grains and grain-rock interfaces in the presence of fluids/lubricants of various viscosities. The outcomes of the project will put an important innovative contribution to the state-of-the-art research associated with environment-soil interaction and the development of cutting-edge experimentation at the scale of grain interfaces.