摘要
饱和土体的固结过程伴随着土骨架的压缩和孔隙水的排出,其孔隙比及渗透系数随固结过程不断减小,但当前的Biot和Terzaghi固结理论均没有考虑固结过程中孔隙比及渗透系数的变化。这种处理方法对于压实土地基的固结过程来说,计算结果与实际相差甚微,但对于孔隙比很大的欠固结软黏土层、尾矿堆积层以及淤地坝库区的固结沉降来说,计算结果与实际过程的差异则会很大。首先建立土体固结过程中孔隙比与体应变的关系式,再利用渗透系数与孔隙比的关系式建立了渗透系数与体应变的关系式,最后利用弹性力学的几何方程得到渗透系数与单元位移的关系式。将这一关系式代入Biot固结理论,即得到变渗透系数固结理论,并在COMSOL中实现了求解计算。理论分析和数值计算表明:变渗透系数固结理论能够反应固结过程中因孔隙比减小造成的孔压消散缓慢、沉降速率降低的客观现象;土体初始孔隙比越大,体应变越大时,修正的渗透系数对固结过程的影响越大;渗透系数的减小只影响固结过程,不影响固结计算的最终结果。
The consolidation process of saturated soil is accompanied by the discharge of pore water and the compression deformation of soil skeleton.The pore ratio and permeability coefficient of saturated soil decrease continuously with the consolidation process.However, both of the current Biot and Terzaghi consolidation theories do not take into account the changes in pore ratio and permeability coefficient during consolidation.The calculation results of this treatment for the consolidation process of compacted foundations are slightly different from the actual results, but for the consolidation settlement of the under-consolidated soft clay, tailings accumulation layer and warping dam reservoir with large pore ratios, the difference between the calculation results and the actual results is too noticeable to be neglected.In this paper, the relationship between pore ratio and volumetric strain of soil mass was firstly established, based on which, the relationship between permeability coefficient and pore ratio, volumetric strain and displacement was established.Then, the relationship was applied to the traditional Biot’s consolidation theory and thus a new formula was acquired, which can consider the variation of porosity ratio and permeability coefficient.Finally, the calculation was realized in COMSOL,and its rationality and reliability were verified by theoretical and experimental analysis.Results reveal that the Biot’s consolidation theory considering permeability coefficient variation can reflect the objective phenomenon that pore pressure dissipates slowly and settlement rate decreases due to pore closure in the consolidation process.The larger the bulk strain of soil, the greater the influence of the modified permeability coefficient on the consolidation process.The modified theory proposed in this paper only affects the consolidation process without affecting the consolidation result.
作者
党发宁
宋靖宇
周玫
张乐
DANG Faning;SONG Jingyu;ZHOU Mei;ZHANG Le(State Key Laboratory of Eco-hydraulics in Northwest Arid Region,Xi'an University of Technology,Xi'an 710048,China)
出处
《中国水利水电科学研究院学报（中英文）》
北大核心
2022年第6期506-515,共10页
Journal of China Institute of Water Resources and Hydropower Research
基金
国家自然科学基金项目(51979255,51679199)
陕西省重点研发计划重点产业创新链(群)项目(2022ZDLSF07-02)。
关键词
孔隙比
体应变
渗透系数
BIOT固结理论
COMSOL
数值计算
void ratio
bulk strain
permeability coefficient
Biot's consolidation theory
COMSOL
numerical calculation
