Research For Microstructure Of Hangzhou Soft Clay

in Hangzhou, there is large area of soft clay. It has high compressibility, low bearing capacity and high porosity. Soil macro-mechanical properties depend on soil microstructure. Soil mechanical behaviors can be better understood by its microstructure, then the research results of soil microstructure can be used for macro-mechanical calculation. In previous research, the soft clay is studied from the macro perspective of the physical and mechanical properties. It is unable to reveal the mechanism of inner nature which contributes to these properties. For this, the soft clay is studied from the view of microstructure in the paper. There are three key problems in the study of soil microstructure:the first is the preparation technique of structure sample, the second is the quantitative study of soil microstructure, the third is the relationship between the microstructure and the macro-mechanical properties. Therefore, the soft clay in Hangzhou was taken as the research object, it was studied from the aspect of the formal three key problems. The main experiment works were as following:(1) Based on the existing soil microstructure test method, a better method to make SEM soil sample that could keep the original structure was given. The reasonable SEM testing parameter was studied too. And The Gray Threshold Partition Method was proposed according to soil porosity obtained in laboratory tests.(2) The microstructure characteristics of Hangzhou soft clay was observed using scanning electron microscope (SEM), and was described from the morphology of the particles, the form of permutation and combination, the contact form and the pore characteristics.(3) The microstructure characteristics of Hangzhou soft clay was quantitatively studied here using Image Pro-Plus (PP) software. The quantitative parameters of soil microsturucture were calculated, the reliability of quantitative research was analized here, The quantitative relation between micro and macro was established.(4) Scanning electron microscope (SEM) microstructure research technique was introduced in the practice engineering, Hangzhou Wulin-square underground space development project was taken as an engineering example here, Scanning electron microscope (SEM) microstructure research technique was introduced, and the unified calculation theory of water and earth pressures was applied, then the parameter ζ, which means pressure coefficient of soil-water coaction could be calculated, as well as the active earth pressure. The unified calculation theory of water and earth pressures could be applied into engineering practice well.