Experimental Study On Anisotropy Of Loess

With the implementation of"The Belt and Road Initiative"and other strategies,the characteristics of loess anisotropy in northwest China have more and more important influence on the design of composite foundation in loess region.At present,there is a lack of research in this field.Therefore,it is necessary to study the anisotropy of loess deformation.This paper takes loess from a construction site in qindu district of xianyang city as the object of study.Five kinds of loess soil samples with different depositional faces in xianyang area were sampled.The deformation anisotropy of undisturbed and remolded loess was analyzed under different moisture content.The anisotropy test of undisturbed loess and remolded loess shows that the anisotropy of both decreases gradually with the increase of water content until the saturation state tends to isotropy.But both in the direction of the low moisture content of five different anisotropy has showed the size of their relationship,undisturbed loess compression modulus of anisotropy of major principal stress direction is greater than the inclined 45 degrees in direction is greater than the intermeditate principal stress,minor principal stress direction,etc.,and reshape the loess compression modulus of anisotropy of major principal stress direction is greater than the inclined 45 degrees in direction is greater than the other three directions,and the other three direction approximately equal.Undisturbed and remolded loess e-p curves with different water content under various anisotropic conditions were obtained by consolidation test.The pore ratio of undisturbed and remolded loess under anisotropic conditions was fitted by mathematical model.The results show that the pore ratio of parameter A and different water content under the anisotropic condition has A corresponding proportional relation,and the parameter B is directly proportional to the compression modulus of the original and remolded loess.Therefore the compression modulus of undisturbed and remold loess in the initial pressure range,the final pressure range and the anisotropic conditions in the common vertical consolidation pressure range in engineering all weaken with the decrease of water content,And the performance of the respective compression modulus is consistent with the magnitude law of the previous direction.Then the consolidation test of xi'an loess was carried out to verify the rule.Finally,the equation e_undand e_remof the pore ratio of undisturbed and remolded loess under the condition of anisotropy were obtained through the equation of pore ratio of undisturbed and remolded loess under the condition of anisotropy.The pore ratio of soil under the direction of major principal stress under the pressure P and the optimal water content could be used to obtain the other water content and the pore ratio of other directions.By comparing the design specification of composite foundation,it can be extended to the calculation formula of the underlying bedding of composite foundation under the condition of considering anisotropy.Therefore,it can provide a theoretical reference for the calculation of pile spacing under the anisotropic condition.