Artificial ground freezing has been applied to many geotechnical projects as temporary and permanent ground stabilization. This paper presents numerical formulations implemented in SMAP-T2, which is specially designed for geotechnical applications of heat transfer problems, along with a new efficient method to compute average heat capacity at freezing point. As one of the practical applications, a frozen backfilled egress shaft is presented in this paper. The aim of this example is to evaluate time requirements for freezing and maintaining the frozen shaft, to evaluate freezing front migrations and possible insulation schemes, and to assess the relative advantages of various stemming materials such as pure water and combinations of soil/water mixtures.

The seasonally frozen ground has been focused on as research topics such as the frost heaving under the asphalt road rather than the permafrost ground due to the latitudinal location of Korea. However, the recent construction of the second Korean Antarctic research station, the Jangbogo station and the participation on the development of the natural gas pipeline in Russia arouse the research interests on the behavior of the permafrost ground. At the design process of the geotechnical structures on the permafrost ground, the evaluation of the mechanical characteristics of frozen soil is very important. In the laboratory tests, it is crucial to understand the effects of testing conditions such as loading rate and temperature on the mechanical behavior of frozen soils. Therefore, unconfined compression tests are performed to evaluate the loading rate effects on the mechanical characteristics of frozen granular soils. Based on the experimental results, the loading rate affects both the strength and deformation characteristics of the frozen soils. The ASTM standards on the loading rate of the frozen sands are fast enough for the strength evaluations but not for the stiffness evaluations. Furthermore, the loading rate effects are evaluated on the bearing capacity and deformation of pile installed on the permafrost via numerical analyses with experimental results.

A dusty thermal vacuum chamber (DTVC) containing a regolith simulant bed is essential for testing equipment and techniques related to lunar surface exploration. Space agencies have been reluctant to operate a DTVC because of the challenge of controlling soil disturbance of the lunar regolith simulant bed during pumping down or depressurization, which may contaminate or even damage the chamber and vacuum equipment. There appears to be no previously available solution to this problem, or how to avoid it. We investigated the mechanism of soil disturbance during depressurization and established a criterion for evaluating its occurrence. The proposed criterion was validated by extensive experiments and numerical modelling to simulate air evacuation from soil voids. There is a critical pressure difference (CPD) between the top and bottom of the lunar regolith simulant bed that causes soil disturbance during depressurization. We found a simple equation estimating the CPD and further provided guideline on the optimum depressurization rate to avoid soil disturbance before the target vacuum level is achieved under varying soil conditions.

In situ capping is one of the preferable remediation technologies for sediments contaminated by heavy metals because of its relatively modest cost. However, it has been used to isolate heavy metals without having detailed information available regarding the effect of consolidation and the chemical isolation caused by in situ capping. This paper presents a numerical estimation of in situ capping efficiency for mitigating heavy metals in sediments when a groundwater flow condition is included. Numerical simulations were conducted using a computational model (CST2) in which contaminant transport occurs by advection, dispersion, and sorption. The results from numerical simulations indicate that the discharge rate of dissolved heavy metals increases during and for some time after capping installation but decreases because of a significant reduction in advection after 100% consolidation. In addition, tailing effect which is the main reason for the long term release of heavy metals is caused by consolidation. Further simulations shows that a multilayered capping system with a thin reactive layer provides an effective barrier to contaminant transport even though consolidation caused by in situ capping results in the negative effects on mitigating heavy metals.