One-Dimensional Large-Strain Rheological Consolidation Analysis Of Saturated Soft Soil Ground

When constructing infrastructure projects in areas along the rivers and coastal of our country where there are deep and thick soft soil layers,problems such as excessive settlement and excessive settlement speed of the foundation will be encountered.The theoretical basis of traditional settlement prediction methods is generally Terzaghi’s consolidation theory,but the latter is based on the assumption of small strain.Based on this,the predicted settlement results of the foundation often differ greatly from actual results.Therefore,in order to further explore the one-dimensional large-strain consolidation mechanism of saturated soft soil,this paper uses a high pressure consolidation odometer to conduct one-dimensional rheological consolidation tests on saturated and remolded soft soil in Xinyang,Henan Province,and verifies the applicability of the unified hardening(UH)model considering the time effect.At the same time,UH model is introduced to describe the elasto-viscoplasticity strain of saturated soft soil during consolidation.Non-Newtonian index flow equation is introduced to describe the non-Darcian characteristics of flow.Then considering the influence of factors such as the distribution pattern of initial effective stress and time-dependent loading,one-dimensional large-strain consolidation equation is deduced,and the finite difference method numerical calculation formulas of the equations are given.Moreover,the calculation program is written with Fortran software.The correctness of the algorithm is verified by comparison with the experimental results of this paper and related research.Finally,the influence of related parameters on the one-dimensional large strain consolidation properties of saturated soft soil are investigated.The main conclusions are as follows:(1)The unified hardening(UH)constitutive model considering the time effect has good applicability to saturated soft soil.(2)In the early stage of rheological consolidation,the viscosity of the soil causes the increasing of excess pore pressure at the undrained boundary.In addition,increasing the secondary consolidation coefficient,non-Newtonian index,the thickness of the foundation soil layer,the overburden load of the foundation and extending the loading duration will all intensify this phenomenon.Moreover,considering that the initial effective stress increases linearly along the depth and when calculating by the large strain consolidation theory,the phenomenon is more obvious.However,decreasing the permeability index and initial permeability coefficient will weaken this phenomenon.(3)Increasing the non-Newtonian index,the secondary consolidation coefficient and the thickness of the soil layer will all delay the dissipation of the pore pressure in the foundation and increase the settlement of the foundation at the same time.However,increasing the external load and permeability index will speed up the dissipation of the pore pressure in the foundation.In addition,changes in the permeability index and non-Newtonian index will have no effect on the final settlement of the foundation.(4)Compared with the assumption of small strain,the pore pressure in the foundation dissipates faster when calculating by the large strain consolidation theory,and the settlement of the foundation is also larger.Compared with the case where the initial effective stress is uniformly distributed along the depth,when the initial effective stress increases linearly along the depth,the pore pressure dissipation rate and settlement rate of the foundation in the early stage of consolidation are slower,but in the middle and later stages,the settlement and consolidation process of the foundation both are faster.And the final settlement is also larger.(5)The time-dependent loading has a great influence on the rheological consolidation of the foundation: extending the loading duration will delay the dissipation of the excess pore pressure in the foundation and the settlement process of the foundation at the initial stage of consolidation.But it has a small effect on the rheological consolidation of the foundation in the middle and later stages of consolidation.