Study On Experiments And Engineering Applications Of Induced Anisotropy Of Granite Residual Soil

Granite residual soil is widely distributed along the southeast coast of China and itis one of the most important soil constructors have to deal with in Fujian Province.Granite residual soil has different engineering properties from sedimentary soilbecause of its special genesis and composition structure. In order to avoidengineering accident and wasting in practice caused by unacquaintance with theseproperties, it is necessary to carry on systematic study on the engineering propertiesof granite residual soil.laboratory soil test is one of the most important method to study on the parametersof soil strength and deformation as well as constitutive model. There are twoinfluencing factors in laboratory tests, sampling disturbance and anisotropy. In thispaper, the traditional test method applying small-sized specimens and isotropicconsolidation is changed. large-sized specimens can be used to weaken the influenceof sampling disturbance and inherent anisotropy, and K0consolidation is adopted torestore the soil specimens to the state of induced anisotropy. Based on the changedtest methods, influences of induced anisotropy on the engineering properties ofgranite residual soil are studied.Compared to the other constitutive models of soil, Hardening-Soil model canreflect the deformation rule of soil more entirely. And it can be used in the numericalsimulation of foundation pit engineering. But the theory of Hardening-Soil model isbased on traditional triaxial test and incapable of considering the influences ofinduced anisotropy. In this paper, the Hardening-Soil parameters of granite residualsoil is adjusted based on the changed test and a set of parameters of Hardening-Soilmodel under induced anisotropy is presented for granite residual soil. Based onpractical engineering, applicability of this set of parameters for foundation pitengineering of granite residual soil is demonstrated.The results show that,(1) Specimen size and consolidation method have great influence on the stress-strain relationship and shear strength indices of the granite residual soil.Large-sized specimen and K0consolidation can make the results more suitable to thein-situ consistence of soil.(2) The engineering properties of granite residual soil under the status of inducedanisotropy have significant differences to the results of traditional tests and theparameters of Hardening-Soil model change as well.(3) The Hardening-Soil-model parameters under induced anisotropy for graniteresidual soil preserve the advantages of traditional Hardening-Soil-model parametersand they also can reflect the effects of induced anisotropy. When used in thefoundation pit engineering of granite residual soil, this set of model parametersobtain more accurate prediction results.