考虑非达西渗流的天然结构性软土大应变非线性固结

天然软黏土的结构特性、大应变特性及低水力坡降下软黏土中的非达西渗流已渐被熟知。但同时考虑天然软黏土结构特性和非达西渗流的软黏土大应变固结理论仍鲜有报道。考虑非达西渗流和天然软黏土的结构特性对固结性状的影响,在拉格朗日坐标系中建立变荷载下软土一维大应变固结模型,并获得其有限差分数值解。在此基础上,与非达西定律下不考虑结构特性影响的软黏土大应变固结解对比,分析验证本文解的可靠性。最后,着重分析了非达西渗流、天然软土结构特性及外荷载对软黏土大、小应变固结性状影响的特征。结果表明:非达西渗流下土的固结速率相对于达西渗流延后,且非达西渗流参数越大固结速率延缓越明显,但其对土层最终沉降值无影响。相同非达西渗流参数下大应变固结速率快于小应变固结速率,但非达西渗流参数并不影响大、小应变固结速率的差异。当外荷载小于天然软黏土结构屈服应力时,土层在荷载作用下应变值较小,大、小应变固结速率的差异可忽略;随着外荷载的增加或结构屈服压力的减小,土层应变值逐渐增大,大、小应变固结速率的差异越明显。

Analysis on Nonlinear Large-strain Consolidation of Structured Soft Clay by Considering Non-Darcy Flow

Structural characteristics,large strain,and non-Darcy flow characteristics under low hydraulic gradient of natural soft clay have been gradually understood. Theory research considering both structural characteristics of natural soft clay and non-Darcy flow was rarely reported. By taking the influence of non-Darcy flow and the structural characteristics of natural soft clay into account, an one-dimensional large strain consolidation model under various loads was established in the Lagrange coordinate system, and the corresponding finite difference numerical solution was obtained. Meanwhile, the results were compared with the large-strain consolidation solution without considering the influence of structural characteristics. The reliability of the solution in this paper was analyzed and verified. Besides, the influences of structural characteristics of natural soft clay, non-Darcy flow characteristic, and external loads on the consolidation behavior were emphatically analyzed. Results show that the consolidation rate considering non-Darcy flow is slower than that without considering Darcy flow. This consolidation delay phenomenon becomes more obvious with the growth of non-Darcy flow parameters. However, the final settlement value is nearly the same. When under the same non-Darcy flow parameters, large-strain consolidation rate is greater than small-strain consolidation rate, while there is no effect on consolidation rate difference between large strain and small strain. In addition, the soil strain is small when the external load is less than the yield stress of natural soft clay, and the corresponding consolidation rate difference between large strain and small strain can be negligible. With the increase of the external load or the decrease of the yield stress, the soil strain increases gradually, and the difference between consolidation rate of large strain and small strain becomes obvious.