考虑流变效应的软黏土地基大应变固结研究

Study on large strain consolidation properties of soft soil considering rheological effect

软黏土压缩性高,在固结过程中变形较大时需要考虑大应变的影响。同时,软黏土具有明显的流变效应,对地基的长期沉降有着重要影响。为此,基于通用有限元软件ABAQUS平台编制土体流变模型UMAT子程序,进行软黏土地基大应变流变固结分析。比较大应变与小应变固结过程中超静孔压消散与沉降发展的差别,并分析模型参数对计算结果的影响。采用半对数经验公式考虑渗透系数随孔隙比的变化,分析渗透指数对固结过程的影响。研究结果表明:大应变固结最终沉降比小应变小,超静孔压消散比小应变快;土体固结对模型中Hooke体弹性模量的变化比Kelvin体弹性模量变化敏感;随着渗透指数的增大,土体固结速率增大。

Soft soil often exhibits large settlement during consolidation because of high compressibility,and so the effect of large strain needs considering.Meanwhile,soft soil also has a significant effect of rheology.Therefore,user subroutine of a rheological model was coded on the platform of the FEM software ABAQUS.The study on large strain consolidation of soft soil was performed,based on which the difference of the dissipation of excess pore pressure and the development of settlement between small strain and large strain consolidation were compared,and the effects of the model parameters were analyzed.The variation of permeability was considered by semi-logarithm empirical formula,and the effects of the permeability index were analyzed.The results show that the settlement of large strain is smaller,and the dissipation of excess pore pressure is more rapidly.The consolidation process is more sensitive to the change of modulus in Hooke spring than that of modulus of Kelvin spring,and the consolidation rate increases with the increase of the permeability index.