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    高压缩性软土一维非线性大变形固结分析

    One-dimensional Nonlinear Large Deformation Consolidation Analysis of Highly Compressible Soft Soil

    • 摘要: 固结理论揭示土体变形随时间的变化规律,高压缩性软土固结特性与压缩和渗透非线性直接相关,而当前大应变固结理论没有充分考虑低应力起始的材料非线性对软土固结特性影响.基于软土孔隙比-有效应力关系曲线的数学表达式和考虑液限影响的软土渗透系数-孔隙比数学表达式,提出以孔隙水压力为变量的一维非线性大变形固结控制方程,采用Crank-Nicolson差分法求解孔隙水压力、沉降固结度和孔压固结度,通过与已有孔隙水压力解析解和实测数据成果对比,验证了孔隙水压力差分解的有效性,并进一步探究初始孔隙比和液限孔隙比对高压缩性软土沉降固结度和孔压固结度的影响特性.研究结果表明,当初始孔隙比为定值时,随着液限孔隙比增加,超静孔隙水压力消散越慢,固结时间增加;当液限孔隙比为定值时,随着初始孔隙比的增加,超静孔隙水压力消散加快,固结时间缩短.

       

      Abstract: Consolidation theory reveals the change law of soil deformation with time,the consolidation behavior of highly compressible soils is related to the varied compressibility and permeability,the current large-strain consolidation theory had not adequately considered the effects of materials nonlinear on the consolidation behavior start from low stress level.Based on the proposed expressions of void ratio- effective stress,and the expressions of void ratio-permeability incorporating the void ratio at liquid limit,the one-dimensional nonlinear large-strain consolidation governing equation with pore water pressure as the variable is proposed.The Crank-Nicolson finite difference method is used for the solution of the degree of consolidation determined from deformation-time curve and the degree of consolidation determined from dissipation of excess pore pressure.The proposed solution is validated by comparing the measured excess pore pressure and the calculated results obtain from existing analytical solutions.The effects of initial void ratio and void ratio at liquid limit on the degree of deformation consolidation and the degree of pore pressure consolidation are also investigated.The results show that,when the initial void ratio remains constant,the dissipation of excess pore water pressure becomes slower with an increase in the void ratio at liquid limit,leading to an increase in consolidation time;when the void ratio at liquid limit remains constant,an increase in the initial void ratio leads to accelerated dissipation of excess pore water pressure,resulting in a shorter consolidation time.

       

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