Structural Characterization And Hardening Soil Model Parameters Analysis Of Granite Residual Soil

The weathered granite residual soil is widely spread in the southeastern part of China.It is a kind of regional special soil.With the rapid development of China's economy,the transportation network has been enriched,and the granite residual soil has gradually become a common carrier and geotechnical material in engineering,but its special structural characteristics make the engineering accidents of this type of soil occur frequently.In view of this,the thesis selects some granite residual soil of a slop in Bozhi County,Zhaoqing City,Guangdong Province as test samples,and conducts a series of direct shearing,consolidation and triaxial tests to multi-dimensional characterize the structural characteristics of granite residual soil.We also study the parameters of the hardening soil model of the undisturbed soil and the remolded soil and provide reference for related engineering.In the direct shear and consolidation tests,the variables of the undisturbed samples are loading direction and saturability,and the variables of the remodeled samples are water content.The test results show that the undisturbed soil exhibits obvious anisotropy,disturbance and water softening.The internal friction anglejof remolded soil decreases with the increase of water content,and the cohesion c first increases and then decreases with the water content.The structural potential parameter increases rapidly with the increase of the stress level until it reaches a peak and then decreases,and finally stabilizes,showing that the structural strength of the compression test is about 100-200 kPa.The structural potential parameter increases first and then decreases with the increase of water content,and reaches a peak when the water content is about 28%,which has the best structure.Triaxial compression tests were applied to undisturbed soil,remolded normal consolidated soil and remolded over-consolidated soil.The experimental results show that both undisturbed soil and remolded over-consolidated soil exhibit certain structural characteristics,the volume change of drainage shear both show obvious dilatancy,and the stress-strain curves show strain softening.The excess pore pressure of undrained shear increased first and then decreased,but the excess pore pressure of undisturbed soil decreased more steeply.The initial Janbu stiffness constants n of undisturbed soil and remolded soil are 0.1328 and 0.6535 respectively,K are 208.64 and 31.99 respectively.The value c?jof undisturbed soil are larger than that of remolded soil.The valuejof overconsolidated soil is close to that of remolded normal consolidated soil,and the value c is larger than remolded normal consolidated soil.The undrained shear strength of overconsolidated soil is in accordance with the SHANSEP theory,and the test constant?43?₀ is 0.6676.The normalized stiffness of remolded normal consolidated soil decreases slowly with loading,Completely yielding when ?₁=15%.The normalized stiffness curves of undisturbed soil and remolded overconsolidated soil cannot overlap,and structural yielding occurs at ?₁=1.5%and ?₁=1%,respectively,and both completely destruction at about ?₁=15%.The larger confining pressure,the closer development feature of the stiffness curve of structural soil is to remolded the soil.The HS model parameters of undisturbed soil and remolded normal consolidated soil are all located in the common range.The three strength parameters?c?????of the undisturbed soil are larger than that of the remolded soil.The three stiffness modulus of the undisturbed soil(E₅₀^ref?E_ur^ref?E_oed^ref)are also larger than that of the remolded soil,but m is smaller than the remolded soil.TheK₀ of undisturbed soil is smaller than that of remolded soil,whileR_f is larger than that of remolded soil.