考虑有效应力的软土固结系数变化规律

Variation Characteristics of Coefficient of Consolidation for Soft Soil Considering Effective Stress

在渗透系数与孔隙比以及有效应力和孔隙比的2类经验回归拟合关系的基础上,推导出固结系数和有效应力的表达式,通过算例和室内试验研究了不同固结应力软土压缩过程中固结系数的变化规律,同时提出考虑有效应力的软土固结系数三次多项式拟合回归方程.研究结果表明:随着有效应力的增加,考虑固结系数变化的软土地基固结速率,相对于太沙基固结理论预测的固结速率,会在一定程度上加快(压缩指数Cc与渗透指数Ck的比值Cc/Ck<1)或减缓(Cc/Ck>1)土体的固结,Cc/Ck=1时,与太沙基固结理论假设一致;采用统一的三次多项式拟合固结系数与有效应力的关系,达到了很好的拟合效果,此结果为数值分析中参数选取的准确性提供了保障,能较准确预估软土地基的变形速率.

Based on two kinds of experimental regression and fitting relationship between coefficient of permeability and void ratio as well as the relationship between effective stress and void ratio of soil, an expression between coefficient of consolidation and effective stress is derived. A series of calculation examples and laboratory test are conducted to study the variety law of coefficient of consolidation of soft soil with different consolidation stress under compression, and proposes the cubic polynomial regression and fitting equation on coefficient of consolidation of soft soil considering effective stress. The obtained results verified that when the variety in coefficient of consolidation of soft soil under an increase of effective stress is considered, consolidation rate of soft soil foundation is usually faster （ Cc/Ck 〈 1 ）, or slower （ Cc/Ck 〉 1 ） than traditional Terzaghi consolidation theoretical calculation of it. The proposed result reduces to Terzaghi＇s theory for a special case of Cc/Ck = 1. An unified cubic polynomial fitting relationship between coefficient of consolidation and effective stress is adopted in a very good fitting effect. The positive results can increase the accuracy for the numerical analysis of consolidation, and deformation rate of soft soil foundation can be predicted accurately.