QUANTITATIVE APPROACH ON MICRO-STRUCTURE OF ENGINEERING CLAY
This present paper concerns with the micro-structure of engineering clay and the method as well as the equipments to deal with it.At first, two instruments are introduced, one of them is a Temperature Gradient Vacuum Sublimation System designed by the author to dry the quiekly freezen samples of undisturbed clay. The success in developing of this equipment highly raises the degree to keep samples for structure analysis undisturbed, which has supplied reliable premise for later work; another equipment is a computed image processing system developed by the author Hefei Polytechnic University for quantitatively studying of the micro-structure from clay's micro-images, by which, more quantitative informations about clay's micro-structure can be gotten.With system ideas, the these is analyses theoretically the engineering clay as a system, dividing the levels of clay structure, pointing out the main structure levels. It is concluded that the system of engineering clay has not fixed structure pattern but the structure state that may relatively stable at certain time and changes from one state to another with the variation of engineering circumstances. It is suggested that the confusion degree of the connections between clay particles can be used as quantitative parameter reflecting clay structure state and raised the concept of the entropy of structure state, pointing out its properties.From mechanic tests and structure analysis on Ningbo clay, following facts have been found:( 1 ) The arrangment entropy of clay reduces by logarithm with time under the charge of certain pressure.( 2 ) The entropy of clay goes down by logarithm with the increase of pressure.( 3 ) In average values, the area of particles of clay become bigger when pressure get to certain value, and the bigger the pressure is, the quicker the increase rate is.( 4 ) The average shape parameter of particles of clay is also becoming bigger with the increasing of pressure. This reflects that the particles are becoming flater and flater.It may be considered that these phenomenon of structure change of clay that are different from the other materials is the source of the special mechanical properties of clay system. Based on the changes of structure parameters of clay under charge of pressure stress and time, the mechanism of clay's behaviours under pressure has analysed, pointing out that the structure evolution is the internal facter of all properties and functions of clay.Finally, The paper points out possible foreground of utilities of micro-structure parameters by studying the relations between structure parameters and the engineering properties of clay.