基于考虑时间效应UH模型的一维固结分析

结合考虑时间效应的统一硬化(UH)模型得到一维固结下土的一维应力-应变关系,以此建立一维固结控制微分方程,可以统一考虑土的主、次固结变形.采用差分方法对单面排水固结问题进行了分析,加载初期不透水层处存在有效应力减小的松弛现象,推导了不透水层处有效应力随时间减小的公式并进行分析.随后,采用数值方法分析了次固结系数、超固结度、压缩回弹系数等因素对固结的影响规律,分析结果也验证了所得公式的结论.此外,通过室内试验对控制方程预测规律进行了验证分析.当主固结基本完成后,变形主要由次固结产生,基于这个条件推导了平均固结度与时间的关系,该公式可以用于计算固结基本完成需要的时间.

1D-consolidation analysis based on UH model considering time effect

The soil stress-strain relationship under 1D consolidation condition was derived from the unified hardening (UH) model considering time effect. Based on this, a governing differential equation of 1D consolidation was established, which could simultaneously describe the deformation behavior of both primary and secondary consolidation. The one direction drainage consolidation problem was analyzed by the differential method. Since there is the phenomenon of relaxation that the effective stress pressure near the impermeable layer would decrease during the initiation of loading, a formula that can reflect the decrease of effective stress by time was deduced. Then, numerical analysis of the influence of secondary consolidation parameter, over consolidation ratio and the consolidation and swelling index was made and the results prove the conclusion of the formula. Besides, the laboratory tests were used to confirm the numerical prediction results of the governing equation. Depending on the condition that when the primary consolidation was almost finished, the main deformation was produced by secondary consolidation, a relationship between average degree of consolidation and time was deduced, which could be used to predict the time when primary consolidation would be finished.