Experimental Study On Mechanical Properties And Micro-structure Of Structural Clay

Research on the micro-structure of natural geotechnical material, which generally has astrong and complex structure, has been the difficult point and forefront. The macro characteristicsare concerned with the change of the microstructure, so to find out the evolvement rule of themicrostructure can provide the foundation to the research of the mechanical properties and clarifythe damage reasons of the geological engineering structure. In this paper, both methods of macrotest and micro-structural analysis are used to study Xuzhou Q3clay. The mechanicalcharacteristics and the micro-structural evolution of the structured clay are researched, and acritical state constitutive model has been proposed. Research in this paper can further provide thefoundation to the research of the mechanical properties.The main research contents and innovation achievements are as follows:1. One-dimensional consolidation tests have been conducted to study the influence ofstructure yield stress and stress history on undisturbed and remolded clay.2. By using GDS triaxial apparatus, consolidation triaxial tests under middle-highpressure have been conducted to study the mechanical characteristics of clay samples withdifferent stress paths and different pre-consolidation pressure. According to the macro test data,the difference of undisturbed and remolded clay samples are discussed, which should be as areflection of structure stress.3. Structure clay has the certain final state so that a critical state constitutive model has beenproposed to reflect the structure properties. In this model, the initial anisotropy tensor was beenintroduced to reflect the initial structural and anisotropy after consolidation. The structuralparameter has been used to describe the structural failure under disturbance of load. This modelhas been proved to be suitable by comparing with part of test data.4. Parallel tests are conducted to study the micro-structural morphology in the process of consolidation tests and triaxial tests. Amount of SEM pictures are taken by the Scanning ElectronMicroscope, and by working with those pictures we can obtain the information of themicro-structural parameters. The evolution of micro-structural parameters along with the consolidation strain and the different stages of triaxial tests with different stress paths anddifferent pre-consolidation pressure are also discussed in this paper.This thesis has79figures,18tables and referred to109articles.