| Due to the structural and anisotropic characteristics of the natural sedimentary soils,it will exhibit different compression and strength mechanical behavior in the conventional one-dimensional Ko consolidation tests and tri axial isotropic consolidation tests.In this paper,the undisturbed and remolded samples of natural sedimentation clay in Fuzhou are used for compression and triaxial tests,including:one-dimensional K0 compression,isotropic compression Comparison tests and isotropic consolidated undrained shear triaxial and K0 consolidation undrained shear triaxial Comparison tests.The influence of different consolidation conditions and structural characteristic on the mechanical properties of natural sedimentary soils was studied.The main research contents and results are as follows:(1)Compression tests under different consolidation conditions are performed on natural and remolded Fuzhou clays.Test results show that on one dimensional K0 consolidation compression and isotropic consolidation compression tests,the compression curves of one dimensional K0 consolidation compression and isotropic consolidation of undisturbed soil are all above the remolded soil,and the compression curves of undisturbed soil have obvious inflection point.The yield stress of isotropic compression is greater than that of one-dimensional K0 consolidation compression,and the compression index of soil sample obtained by one-dimensional compression test is significantly larger than that of isotropic compression.The compression curves of remolded soils in the Iv-Ig?x' coordinate system are basically coincident with the intrinsic compression line proposed by Burland,and the compression curve of the undisturbed soil is located above the intrinsic compression line.The stress sensitivity of isotropic consolidation is higher than that of one-dimensional K0 consolidation.(2)Based on the analysis of consolidated-undrained triaxial shear test results of different consolidation conditions:The stress-strain curve obtained from the undrained consolidation test of the undisturbed soil is slight strain softing type,and the stress-strain curve of the K0 consolidation undrained shear test is obvious strain softing type,with the increase of the effective consolidation stress of K0 consolidation,the degree of softening is more obvious.The stress-strain curves of the remolded soil and the undisturbed soil obtained from consolidation and K0 consolidation can be normalized after the yielding of the structure.Secant modulus E50 obtained from K0 consolidation test was significantly higher than that of isotropic consolidation test.(3)Based on the analysis of the strength obtained from triaxial.test:The relationship between the undrained strength obtained from K0 and isotropic consolidation and the moisture content after consolidation is almost on the same curve.The relation curve between the undrained strength and the modified water content obtained from undisturbed soil is located above the remolded soil,and the increase of effective consolidation stress will make them tend to be consistent.The total stress intensity envelope of undisturbed soil is composed of two straight lines before and after yielding,and the slope of the total stress intensity envelope obtained by K0 consolidation test is obviously larger than that of the isotropic consolidation.The effective internal friction angle obtained by K0 consolidation test is smaller than that of isotropic consolidation,but the effective cohesion value of the their are very close. |
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