A three‐phase thermo‐hydro‐mechanical finite element model for freezing soils
A three‐phase thermo‐hydro‐mechanical finite element model for freezing soils
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DOI：
10.1002/nag.2184
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发表时间：
2013-12
影响因子：
4
通讯作者：
M. M. Zhou-M.;Günther Meschke
中科院分区：
文献类型：
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作者：
M. M. Zhou-M.;Günther Meschke
人工冻结法是岩土工程中常用的一种软土隧道施工中的地下水控制和开挖临时支护等地基处理技术。与该技术相关的主要潜在问题是，它可能在地面产生隆起和沉降，这可能对地面基础设施造成损坏。此外，冻结过程和获得稳定冻土所需的能量可能会受到渗流的显著影响。显然，AGF的安全设计和执行需要可靠地预测冻土的耦合热-水-力学行为。基于孔隙力学理论，提出了以固体颗粒、液态水和结晶冰为分离相，以混合物温度、液体压力和固体位移为主要场变量的三相有限元土模型。除了水转化为冰的体积膨胀外，微低温抽吸机制对冻胀现象的贡献在模型中使用预融动力学理论来描述。通过基本的物理定律和相应的状态关系，该模型捕捉相变之间的各种耦合，在孔隙空间内的液体传输，以及伴随的机械变形。模型的验证和确认是通过选定的分析。一个应用实例与隧道开挖过程中的AGF有关，研究渗流对冻结过程的影响以及建立封闭支撑冻结拱所需的时间。Copyright © 2013 John Wiley & Sons，Ltd.
Artificial ground freezing (AGF) is a commonly used technique in geotechnical engineering for ground improvement such as ground water control and temporary excavation support during tunnel construction in soft soils. The main potential problem connected with this technique is that it may produce heave and settlement at the ground surface, which may cause damage to the surface infrastructure. Additionally, the freezing process and the energy needed to obtain a stable frozen ground may be significantly influenced by seepage flow. Evidently, safe design and execution of AGF require a reliable prediction of the coupled thermo‐hydro‐mechanical behavior of freezing soils. With the theory of poromechanics, a three‐phase finite element soil model is proposed, considering solid particles, liquid water, and crystal ice as separate phases and mixture temperature, liquid pressure, and solid displacement as the primary field variables. In addition to the volume expansion of water transforming into ice, the contribution of the micro‐cryo‐suction mechanism to the frost heave phenomenon is described in the model using the theory of premelting dynamics. Through fundamental physical laws and corresponding state relations, the model captures various couplings among the phase transition, the liquid transport within the pore space, and the accompanying mechanical deformation. The verification and validation of the model are accomplished by means of selected analyses. An application example is related to AGF during tunnel excavation, investigating the influence of seepage flow on the freezing process and the time required to establish a closed supporting frozen arch. Copyright © 2013 John Wiley & Sons, Ltd.