The effect of rock particles and D2O replacement on the flow behaviour of ice

Ice–rock mixtures are found in a range of natural terrestrial and planetary environments. To understand how flow processes occur in these environments, laboratory-derived properties can be extrapolated to natural conditions through flow laws. Here, deformation experiments have been carried out on polycrystalline samples of pure ice, ice–rock and D2O-ice–rock mixtures at temperatures of 263, 253 and 233 K, confining pressure of 0 and 48 MPa, rock fraction of 0–50 vol.% and strain-rates of 5 × 10−7 to 5 × 10−5 s−1. Both the presence of rock particles and replacement of H2O by D2O increase bulk strength. Calculated flow law parameters for ice and H2O-ice–rock are similar to literature values at equivalent conditions, except for the value of the rock fraction exponent, here found to be 1. D2O samples are 1.8 times stronger than H2O samples, probably due to the higher mass of deuterons when compared with protons. A gradual transition between dislocation creep and grain-size-sensitive deformation at the lowest strain-rates in ice and ice–rock samples is suggested. These results demonstrate that flow laws can be found to describe ice–rock behaviour, and should be used in modelling of natural processes, but that further work is required to constrain parameters and mechanisms for the observed strength enhancement

Experimental observations that simulated active-layer deepening drives deeper rock fracture

The impact of changes in active-layer thickness on the depth of pervasive macrofracture (brecciation) in frost-susceptible bedrock is unclear but important to understanding its physical properties and geohazard potential. Here we report results from a laboratory experiment to test the hypothesis that active-layer deepening drives an increase in the depth of brecciation. The experiment simulated active-layer deepening in 300 mm cubic blocks of limestone (chalk) and sandstone. Temperature, surface heave and strain at depth were measured during 16 freeze–thaw cycles. Macrocracks photographed at intervals were digitally analysed to visualise crack growth and to quantify crack inclination and length. In chalk, an upper horizon of macrocracks developed first at about 100 mm depth in a shallow thaw active layer during cycles 1–8, followed by a lower horizon at about 175‒225 mm depth in a deeper thaw active layer during cycles 9–16. The longest cracks (>35 mm) were most common at inclinations of 0–30° from horizontal, and numerous cracks <5 to 15 mm long developed at inclinations of 40–50°, with some longer vertical to subvertical cracks linking the two brecciated horizons. Overall, the observations support the hypothesis that a thickening active layer drives deeper rock fracture by ice segregation

DEM Modelling of Ice Filled Rock Joints

The research we present in this paper is part of a wider project about the modelling of climate change effects on the degradation of permafrost, with particular attention for the stability of rock masses. The presence of ice and/or mixtures of ice and granular materials in rock joints has a big impact on the shear resistance of joints and on the evolution of joint persistence. In previous research we modelled the mechanical behavior of ice and frozen soils with a Distinct Element model and compared the evolution of the resistance with ice content with experimental data available in the literature. In this paper, we are focusing on rock joints and we are modelling both fill material (ice and frozen soil mixtures) and rock as collections of Distinct Elements, taking advantage of the previous experience in terms of calibration of the parameters. In particular, in this preliminary study, we will focus on the shear resistance of joints as a function of the composition of the fill material. The purpose of this research is to study the mechanical behavior of joints and derive the corresponding force-displacement relationship to be assigned to the interfaces between blocks in a full scale model of rock masses

Energy-saving technologies in design and construction of residential buildings and industrial facilities in the far North

The article discusses the main problems of energy saving and special features of design, construction and operation of residential buildings and industrial structures in extreme climatic conditions of the Northern territories. The impact of permafrost, seasonal thawing of soils and low bearing capacity of thawed soils on the choice of ways of arrangement of cities and pipelines in the Northern regions of Russia have been analyzed. There have been assessed the effect of climate change and the associated natural and man-made risks in the Far North on the development of a system of measures to ensure the reliability of energy facilities and options for emergency response. The solutions allowing to increase energy-saving capabilities of buildings and to reduce expenditures at their operation have been designated. Necessity of using non-traditional and renewable energy sources has been considered