Compression Consolidation Rheology Test And Model Analysis Of Soft Soil

Soft soil is a kind of multiphase medium with complex composition and structure.It has always been a hotspot in the research of geotechnical engineering materials.Because the deformation of soft soil has obvious aging characteristics,it has a non-negligible effect on the long-term strength and stability of engineering structures.The aging deformation of soft soil includes consolidation deformation and rheological deformation,among which the stable time of rheological deformation is longer.At present,there are relatively few long-term consolidation rheological tests for soft soils,and a unified understanding of the mechanism of rheological deformation has not yet been formed.In this paper,a long-term one-dimensional compressive consolidation rheology test was conducted with bentonite,kaolin and organic clay as"rheological materials"and quartz sand as the sample of artificial soil to explore the influence of material composition on the long-term rheological properties of soft soil.The long-term rheological curves and rheological laws of soft soils are explored and analyzed by establishing a macroscopic model of nonlinear rheological components and a microscopic creep model based on the concept of"shear migration drainage"and the theory of rate process.The main research contents and results of this paper are as follows:（1）Selecting bentonite,kaolin and organic soil as rheological substances,a series of saturated soft soils with different rheological moisture contents and rheological substance contents were prepared,and a long-term one-dimensional compression and consolidation rheological experiment was carried out.The long-term one-dimensional compression consolidation rheological test results show that the average value of the rheological coefficient k_cr and the secondary consolidation coefficient C_αe of the sample increases with the increase of the rheological content and the rheological water content of the soft soil.At the same time,the rheological material is different,the rheological coefficient and the secondary consolidation coefficient will also be quite different.It shows that the more rheological content in the soft soil,the more obvious the rheological deformation,and the rheological composition has a greater influence on the rheology of the soft clay.（2）The nonlinear elastic element is introduced into the five-element generalized Kelvin model to establish a nonlinear liquid rheological model of saturated soft soil,and to fit the one-dimensional compression and consolidation rheological test results.Through the sensitivity analysis of the model parameters,the relationship between the key parameters and the rheological content and the moisture content of the rheological material is established,which is introduced into the nonlinear liquid rheological model,and a set of simulations of the same rheological material in the The strain-time relationship curves of soft soils under different stress levels have a higher overall fit.（3）Based on the"shear migration drainage creep mechanism"proposed by Prof.Fang Yingguang,the creep rate equation of soil"shear migration drainage"is derived on the basis of the rate process theory,and the"shear migration drainage"creep equation of saturated soft soil is further derived from this.After simplifying the equation into a shear migration drainage creep model,the model was fitted to the test rheology curve after consolidation was completed,and the model was found to be a good fit.