中文摘要：

现有的双层软土地基大变形固结理论均假定土中渗流遵循达西定律,但软黏土中渗流在低水力坡降下会出现偏离达西定律的现象已逐渐为人们认识。综合考虑双层软黏土中的非达西渗流、软土的非线性压缩渗透特性及实际中的变荷载作用,在拉格朗日坐标系中建立以超静孔压为变量的软土大变形非线性固结模型,并给出其有限差分解。在此基础上,通过与已有的非达西定律下单层地基大变形固结数值解计算结果相对比,以验证其差分解的可靠性。最后着重分析上、下层非达西渗流参数m_1、i_（11）及m_2、i_（12）对固结性状的影响,并分析了在大、小变形不同几何假定下对双层地基超静孔压消散及固结沉降影响的异同。结果表明：上层土参数m_1、i_（11）对固结性状的影响要比下层土参数m_2、i_（12）显著;m_2、i_（12）的增大会引起上层土超静孔压消散速率的加快,但双层地基的固结速率会减慢;大变形假定下双层软土地基的固结速率要比小变形假定下快,但两种几何假定下双层地基的最终沉降量是相等的。

英文摘要：

In the current large-strain consolidation theory of double-layer soft soil foundation,it is assumed that the seepage in the soil follows Darcy＇s law.However,it has been recognized that the seepage in soft clay may deviate from Darcy＇s law under low hydraulic gradient.The effects of non-Darcy flow,non-linear characteristics,and time-dependent loading are discussed comprehensively,and a model for the finite-strain consolidation is developed in Lagrangian coordinate by employing the excess pore water pressure as variable.Meanwhile,the corresponding finite difference solutions for this model are provided.On this basis,the numerical solutions for the proposed consolidation model are verified by comparing with the numerical solutions for the large-strain consolidation of a single soil layer foundation with non-Darcy＇s law.The influences of upper layer parameters m_1、i_（11） and sublayer parameters m_2,i_（12_ on consolidation behaviors and the differences in the dissipation of excess pore water pressure and in the consolidation settlement are investigated.The results show that the influences of m_1,i_（11） on consolidation behavior are more evident than m_2,i_（12）.The dissipation rate of excess pore water pressure in upper layer increases with the increase in the value of m_2 or i_（12）,whereas the consolidation rate of double layer foundation decreases with the increase in the value of m_2 or i_（12）.The consolidation rate of double layer foundation under large-strain assumption is larger than that at small-strain,whereas the final settlements under both large-strain assumption and small-strain assumption are the same.