Experimental Study On Anisotropic Properties Of Loess

There are anisotropic properties in undisturbed loess and remolded soil samples.The undisturbed loess in the deposition process,in the horizontal direction of the compression is higher than the vertical direction.The layered structure formed by the undisturbed soil during the deposition has the original anisotropy,and the secondary anisotropy produced by the force action is also caused by the anisotropic properties of the remolded sample and the undisturbed sample the reason.Since the remolded sample also forms a layered structure during the compaction process,the anisotropy characteristics of the loess can be further studied by preparing the remolded sample.The strength and deformation anisotropy of undisturbed loess and remolded loess are analyzed by using the True tri-axial tester,which can reflect the actual stress of the soil.The effects of different conditions on the anisotropic properties of undisturbed loess and remolded loess were compared by means of Deng Kenzhang's(Duncan-Chang)hyperbolic model and axial strain coefficient ratio.The experimental results show that the influence of different confining pressure and the ratio of the middle principal stress on the anisotropy is significant.The increase of confining pressure induces the secondary anisotropy of undisturbed loess.With the increase of the ratio of the middle principal stress,the stress of the middle principal stress increases,and the anisotropy is remarkable.However,the anisotropy does not increase with the increase of the ratio of the middle principal stress.The compressive strength of remolded loess is smaller under the action of vertical large principal stress than that of lateral large principal stress.Finally,the deformation anisotropy of undisturbed loess under vertical and horizontal compression is studied by means of consolidation test.Through the contrastanalysis,compression coefficient was between 0.1MPa-1~0.5MPa-1,the test loess belongs to the medium compressibility loess,consistent with the actual soil;in the process of consolidation of natural loess after deposition,the vertical soil pressure is greater than the horizontal stress of overlying soil caused by gravity,so the horizontal compression is greater than that of vertical compression.