The Study Of The Soft Clay's Structure And Model

Soil structure cy, i.e. the peculiarity,shape and fabric of soil grain and the impact between the grains. Most of the nature soil has some structure cy, soft clay, because of the particular history condition and mineral element, also has structure cy, and the structure type has peculiarity of its own. The structure cy affects the works cy strongly.Soft clay of structure cy has fabric intensity. So it fragility destroy, and destroy stress is small. Soil of structure cy, in works, usually destroy suddenly, and has no forebode. Study the structure cy of soft clay has important meaning to the design of construction, and design of foundation stabilization. Shen Zhujiang believes that soil structure cy is one important element in the elements, which affect the peculiarity of rock mechanics, it's looked as "the core issue of soil mechanics in 21century." The article studies the change feature of undisturbed soil and remolded soil, base on macroscopic mechanic test. The main outcomes as follows:(1) Study the indexes's change confines, changecy, the correlation of indexes's and the statistical distribution regular analysis of indexess, by collecting 158 physical and mechanical indexes datas of un-disturb soft soil. The study result shows that: physical and mechanical indexes of soft soil in different place different greatly; indexes's are relation to w and e;ρ,ρ_d, W_L,W_p,I_p,q_u and st obey the normal distribution; nature moisture content, aperture rate and cohesion obey the normal distribution approximately; S_r,G_s,K_v,a_v1-2,E_s1-2 andφobey the abnormal distribution. The study consequence has important meaning to the soft soil engineering.(2) Studying the structure cy parameter and compression peculiarity of undisturbed soil and remolded soil with structure cy by 3 different means, by consolidation￡compression test, the result shows that the structure cy affects the compression peculiarity a lot; structure cy parameter m_p＞1, when the loading is big, m_p 1; the compression factors of undisturbed soil and remolded soil different a lot at the loading beginning, but the compression factors of undisturbed soil will tent to be equal to the remolded soil's. The author gives the compression￡deformation's tiny behavior of soft clay with structure cy, and shows the compression changing course of the soil sample by the SEM pictures.(3) It can be concluded from statistic and analysis of the test datum of 50 undisturbed soil samples in the same place, that void ratio, moisture content,density and dry unit weight are important influence factors to the compressibility of soft clay. Assaying coefficient of consolidation,coefficient of compressibility and modulus of compressibility on the one-dimensional compression test of undisturbed soil and remolded soil, The result shows that structure cy influents the soft clay's compressibility a lot. The author gives the tiny behavior of compressibility, and expounds some viewpoints of his own.(4) Study the stress -strain relation of soft clay of structure cy in different confining pressure, the influence to the soft clay of structure cy by the stress path, and the change rule of pore water pressure on the triaxial consolidated undrained test and unconsolidated undrained test.(5) The article introduces soft clay's microanalysis working process on soil sample preparation, sample for photo preparation, photos taking of SEM picture, digital picture disposal , etc. Assaying shade of gray histogram, picture threshold value partition, and border detection using MATLAB. Probing influence from threshold value partition and border detection operator to SEM picture. Introducing the SEM picture measuring method and skill using IPP specialized picture analysis software.(6) Assaying changing regular under loading of dimension of grain, average shape coefficient of grain and aperture gap's area, average shape coefficient of aperture gap, aperture gap's number, aperture gap's equivalence caliber, surface pore-solids ratio, surface porosity, aperture gap's roundness, aperture gap's direction finding frequency, etc. using IPP software.(7) The article introduces the destructive ratio concept, ameliorates the Duncan-can model. The ameliorated model can reflect the stress -strain relation of soft clay of structure cy better. Probe the change rule of strain softening and strain hardening of soft clay of structure cy, so the conclusion is there will be different initial elastic model and K,n amounts in the different stage.(8) According to the soil structure's indeterminacy and the non-linearity of its mechanics property, it's a workable way to establish no-linear model of structural parameter using BP nerve lattice model. Study the relationship of structural parameter and structural character parameter. The results show that the aperture gap's total area, the aperture gap's average aperture, and the aperture gap's roundness have close relationship with structural parameter; the aperture gap's dimension, grain's total area, and grain's average aperture have remoteness relationship with structural parameter.