Research On Micro Properties And Slaking Mechanism Of Nanyue Granite Residual Soil

The granite residual soil is distributed Hunan, fujian, guangdong and otherregions widely. Granite residual soil is the final product of disintegrated granite, it’shomogeneity is poor and it is prone to collapse under the influence of water. As theprocess of engineering construction speeds up, the special nature of granite residualsoil is shown gradually in the practical engineering, It has become one of theimportant issue in engineering construction how to solve the granite residual soil isprone to collapse under the influence of water in tunnel and slope excavation as wellas when the granite residual soil is regarded as subgrade filling. Based on laboratorytest and theoretical analysis, the physical characteristics, Microscopic properties,Slaking mechanism and Fractal mechanism of granite residual soi is researched.Based on the granite residual soil in nanyue district as the research object, theundisturbed soil samples ware collected with cutting ring and the disturbed soilsample was taken with spade. Through the screen grade testing, liquid-plastic limitstest and compaction test, the particle size distribution,plastic limit, liquid limit, thebest moisture content and maximum dry density and other physical parameters ofgranite residual soil was determined.The regular get to discover by screening testthat the residual soil particle size basic present the characteristics of\"two head moreintermediate less\"on the overall. Combination with the determination of thescreening test and plastic-liquid limit test results, the granite residual soil in nanyuedistrict is defined as silty clay.the engineering properties of geotechnical is affected its micro characteristicsat a large extent, especially it’s soil softening disintegration, swelling andpermeability etc. The microstructure of original granite residual soil was observatedby scanning electron microscope. When the original granite residual soil was shootfrom low to high power, it’s microstructure presents granular, block, plate, strip,sheet, layered in turn, it’s pore and fracture are development, and it’s structure areloose. From the phase analysis that it is measured by XRD test, the main mineralcomposition of residual soil are kaolinite, water pearl clay, plagioclase, sodiummanganese ore, halloysite, quartz, dickite, hauling and magnesium sulfate etc.The granite residual soil remodeling were studied on indoor disintegration test,with the improved large granite residual soil disintegration apparatus. Based on theimproved method of the initial reading, the disintegration characteristics of graniteresidual soil remake sample with different moisture content and compactness wasdiscussed. Through the factors of disintegration time, disintegrating rate, collapserate,disintegration time ratio at various stages were analyzed, the moisture contentof sample is higher and it’s compactness is greater, the disintegration rate of sampleis smaller and disintegration time is longer, the maximum disruption rate peak issmaller and it is later in time; The Disintegrating residue of sample presents cone,the height and base Angle of the cone are bigger along with the increase of moisture content and compactness of sample.The Six prism specimens and cuboid specimens that were made by Homemadeproofing device of six prism and cuboid combine with the cylinder sample were usedin disintegration test. The disintegration characteristics of granite residual soilremake sample with different shape and compactness was discussed. Theexperimental results show that the angular angle is smaller, the disintegration rate isgreater,the disintegration time is shorter, the maximum peak of collapse rate isgreater and it is earlier in time at the beginning of the sample collapse; In the late ofdisintegration, The influence of the shape on sample disintegration is smaller.The remake samples with different number of airport surface were used indisintegration test. The research shows that reducing the airport surface of graniteresidual soil can effectively reduce the contact area with water, reduce itsdisintegration speed and extend the disintegration time.The parallel samples of granite residual soil reshape samples with differentmoisture content and compactness were used in SEM test. Combined withdisintegration test and SEM test, the disintegration mechanism of granite residualsoil is explored that the kaolinite mineral with the nature of the collapse under theinfluence of water and pore fissure in a sample is the main factor of granite residualsoil disintegration.Finally, based on the fractional Brownian motion model of the fractal theory,the granite residual soil remake sample disintegration rate fractal model isestablished. Its fractal dimension of disintegration rate was determined between1.44~1.66, and the fractal dimension will be larger with the increase of moisture contentof the sample.