The stability performance of the frozen curtain formed under standpipe freezing is closely associated with the weak zone penetrated by thermal gradient-related fracture (TGF). The TGF-rich zone further affects the liquid phase flow when the frozen curtain is thawed. However, there is a lack of studies on the TGF-rich zone within the frozen curtain. To address this gap, a simplified and practical 2D bonded particle model-based numerical simulation strategy was developed to identify the possibility of acquiring field characteristics of the TGF-rich zone by conducting numerical tests on samples considering size effects. The results, validated by the experiment, indicated that the influence of size on crack localization zone was comparable to that of the parameter gradient but had a weaker characteristic on crack orientation, which represents the orientation of TGF. In particular, the characterization result of the TGF-rich zone using crack localization zone in the simulation closely matched that using lateral strain localization zone both in simulation and experiment. Regarding the size effects of the TGF-rich zone revealed in the simulation, the estimated field length of the TGF-rich zone accounted for approximately 30% of the zone width characterized by a horizontal thermal gradient, with maximum orthotropic deformation occurring at about 10% of the zone width. These observations validate the existence of TGF within the frozen curtain and contribute to the development of a precise grouting technique to mitigate subsidence within soil deposits subjected to freeze-thaw.

The Diviner Lunar Radiometer Experiment on the Lunar Reconnaissance Orbiter and the Microwave Radiometer (MRM) onboard Chang'e-2 (CE-2) orbiter performed nearly coincident measurements of the lunar south polar region in 2010-2011. In this study, we reconcile infrared data from Diviner and microwave data from MRM to reveal thermal behavior of lunar regolith at very low temperatures. Assuming a uniform density structure and dielectric properties across the polar region, we retrieve a relative apparent thermal-gradient map based on radiative transfer model. The result shows apparent thermal gradients in the permanently shadowed regions (PSRs) are much larger than that in non-PSRs, which implies a systematic difference in thermal conductivity and/or density of lunar regolith in PSRs. We also model surface temperature and microwave brightness temperature over time in PSR and non-PSR locations. The modeling results at these representative locations and the thermal gradient map confirm that the regolith in the PSRs is consistent with a much lower thermal conductivity and higher porosity than non-PSRs.

Laboratory measurements of physical properties of planetary ices generate information for dynamical models of tectonically active icy bodies in the outer solar system. We review the methods for measuring both flow properties and thermal properties of icy planetary materials in the laboratory, and describe physical theories that are essential for intelligent extrapolation of data from laboratory to planetary conditions. This review is structured with a separate and independent for each of the two sets of physical properties, rheological and thermal. The rheological behaviors of planetary ices are as diverse as the icy moons themselves. High-pressure water ice phases show respective viscosities that vary over four orders of magnitude. Ices of CO2, NH3, as well as clathrate hydrates of CH4 and other gases vary in viscosity by nearly ten orders of magnitude. Heat capacity and thermal conductivity of detected/inferred compositions in outer solar system bodies have been revised. Some low-temperature phases of minerals and condensates have a deviant thermal behavior related to paramount water ice. Hydrated salts have low values of thermal conductivity and an inverse dependence of conductivity on temperature, similar to clathrate hydrates or glassy solids. This striking behavior may suit the dynamics of icy satellites.