Experimental Study On Static And Dynamic Characteristics Of Saturated Soft Clay With Different Degree Of Consolidation

There are saturated soft clay foundations with different degrees of consolidation in the coastal areas of southeast China,including underconsolidated,normal consolidated and over-consolidated soft clay.Soft Clay has poor engineering properties and is prone to instability and excessive deformation under static and dynamic loads.Firstly,there is little research on underconsolidated soft clay,secondly,there is little research on anisotropic overconsolidated soft clay under different stress paths.In this paper,a series of static and dynamic tests are carried out for saturated soft clay with different degree of consolidation The static shear behavior of soft clay with different underconsolidation degree（U）is studied,the influence of over-consolidation ratio（OCR）,over-consolidation stress ratio（K）,stress path（η）,cyclic stress ratio（CSR）and some drainage conditions on the cyclic behavior of anisotropic over-consolidated soft clay is discussed.The main findings and results are as follows:（1）Based on the unconsolidated degree of soft clay reconstructed by volume strain control,triaxial static shear tests were carried out on the unconsolidated soft clay,the results show that underconsolidation degree has a great effect on the pore pressure-strain relationship and stress-strain relationship of saturated soft clay,but has little effect on the static strength envelope,and the underconsolidation degree has a linear relationship with the strength.（2）For under-consolidated soil,the stress-strain relationship is fitted by strain hardening model and strain softening model respectively,and the results show that the stress softening model is effective.（3）Based on dynamic triaxial apparatus with variable confining pressure,the coupling of cyclic deviator stress and cyclic confining pressure is used to simulate the coupling of cyclic normal stress and cyclic horizontal stress under traffic load,the dynamic modulus and dynamic damping law of anisotropic over-consolidated soft clay under different stress paths are studied,and the effects of over-consolidation ratio（OCR）,consolidation stress ratio（K）and stress path slope（η）on them are emphatically analyzed.The results show that the dynamic modulus decreases with the increase of shear strain,and the dynamic damping increases with the increase of shear strain.When the dynamic strain is small(10^-2～10^-1%),the influence of OCR,K,ηon the shear modulus is great;When the dynamic strain is about 0.02%,the effect of OCR on the dynamic modulus is the biggest,and the smaller the K value is,the more obvious the effect of OCR is.（4）Through long-term cyclic loading tests under partial drainage,the cyclic properties of saturated soft clay under anisotropic consolidation,such as axial strain,volumetric strain,axial cumulative strain rate and resilient modulus,are analyzed,the ultimate cumulative strain of soil is smaller,the bulk strain of anisotropic consolidated soil is larger than that of isotropic consolidated soil,the cumulative rate of ultimate axial strain is higher when K value is smaller,and the resilient modulus of clay is lower when K value is lower.