Engineering Cohesive Soil Micro-structure Of The Quantitative Research

Many special behaviours owned by engineering clay can not bedescribed with the methods of conveniently continuous mediummechanics,which makes it difficult to appraise the engineeringcharacters of clay quantitatively.So, it is imperative tore-observe the clay from the structureal features of theclay itself to look for a new way for estimate it.At first of this present paper, the author points out theproblems existing nowadays and the problems to be solvedurgently combining the case in China based on analysis ofhistorical and present situation as well as the tendency of claymicrostructure researches.Then, it introduces a Tempreture Graded Vaccum SublimationInstrument designed by the author to dry the undisturbed freezesamples, which has supassed that reported in Chinaand that in U.S.S.R in the speed of sample preparation and whichprovides a reliable premise for later work.Cooperated with the Computer and Information Department inHEFEI Polytechnic Univesity, the author make researches on thecomputer system for analysing the image of the microstructure ofclay,which is the first time to make quantitative study onclay structure with computer in China.Its success has brought thequantification work of clay structure to a new field.The systematic scientific method is used in the essay to makesystematic analysis on engineering clay.The concepts are putforward about engineering clay structure, the level of structureand structure state from the viewpoint of system.The levels ofclay structure is classfied and the main structure level ispointed out,which make clear the vague concept of claystructure.The author then introduces the concept of structureentropy from the features of engineering clay,considering thatthe entropy can be used as a quantitative parameter to appraisethe structure state of clay system,and its characters are set forth.This opens a new way for quantitative study of soilstructure.Taking NINGBO clay as an example, the author expounds thereducing laws of clay entropy and the changing laws of theelements of microstructure with the data of mechanicalexperiments and the quantitative analysis of clay's structurethat when the pressure stress get to a certain value the clayparticles will have the phenomenen of mutual polymerization andthe phenomenon that the pattern of particle Io be flat,and theexperienced formulas of the structure change of NINGBO clayare given.Then the author analyse the mechanism of structurechange e.g evoluting mechanism,discuss the resources ofthe non-linear stress and strainrelationship,unisotropy,and unconvenient strain handening ofclay.At last,the author point out the relationship between theparameters of microstructure and the mechanical properties ofclay. It is thought that will be a bright future by using theparameters of microstructure to help appraising the claybehaviors,clay classification, rock weathering study,collapsibleloess research and to help establishing the real constitutiverelation of soil.