考虑温度耦合效应的竖井地基固结有限元分析

针对塑料排水板(PVD)安装热源能提升PVD性能、加速竖井地基固结这一工程现象，基于热-水-应力 (T-H-M) 三场全耦合的有限元方法来模拟利用热源进行地基处理新技术(PVTD)。首先，以微分形式与等效弱形式分别给出T-H-M耦合控制方程，并推导出其有限元方程组。然后在多场耦合有限元软件中建立饱和土的T-H-M全耦合模型，并通过与已有解析解比较，验证了模型正确性。最后，对一个经典有涂抹区的竖井地基算例，分不耦合温度(UT)、耦合温度但不考虑其对饱和土物性影响(CT)、耦合温度考虑温度对饱和土渗透性影响(CTP) 3种情况进行固结计算分析。研究结果表明，相对于无热源竖井地基，CT情况下由于热源产生的附加孔隙水压力，固结速度略有下降；CTP情况下，由于热源有效改善涂抹区的渗透性能，竖井地基固结速率明显加快。上述研究结论从理论上较好地阐明了PVTD的作用机制。

Finite element analysis of foundation consolidation by vertical drains coupling thermo-hydro-mechanical effect

Prefabricated vertical drains (PVD) incorporating with a heat source, which can accelerate the foundation consolidation in vertical drains system, is stimulated by finite element method based on the thermo-hydro-mechanical (THM) coupling. Firstly, both differential form and weak form of control equations for THM coupling problems are presented; and the finite element formulations are deduced. Secondly, a fully coupling THM model is established in Comsol Multiphysics software. Comparison between numerical results and analytic solutions are carried out in order to validate the model. At last, a representative calculation example of a single drain foundation in which has a smear zone is adopted. In order to study the influence of the thermal effect on consolidation, the example is modified through a heat source set in the well zone; and three cases (1) uncoupling temperature(UT), (2) coupling temperature without considering the thermal effect on property of soil (CT) and (3) coupling temperature with considering the thermal effect on property of soil(CTP) are executed. The results show that the rate of consolidation decreases a little in the CT case since the heat source produces the extra pore pressure; and increases significantly in CPT case due to the higher temperature enhancing the hydraulic conductivity in smear zone.