Frozen Rock Mass Research Articles

Model of time-distance curve of electromagnetic waves diffracted on a local feature in the georadar study of permafrost zone rock layers

In GPR (georadar) studies, one of the most popular procedures for determining electromagnetic waves propagation velocity in a rock mass is the selection of theoretical hyperbolic time-distance curves and subsequent comparison with the time-distance curve obtained from a GPR measurement. This procedure is based on the model of homogeneous medium, but nowadays the subject of GPR study is often inhomogeneous media, such as horizontally layered media characteristic of loose permafrost zone sediments. The paper presents the findings of studying the formation of hyperbolic time-distance curves of georadar impulses in a horizontally layered medium without taking into account the dispersion and absorption of electromagnetic waves. On the basis of geometrical optics laws, formulas were derived to calculate the shape of the hyperbolic lineup of georadar impulses reflected from a local feature in a multilayer frozen rock mass. On the example of a permafrost zone rock mass containing a layer of unfrozen rocks, the effect of the thicknesses of rock layers and their relative dielectric permittivity on the apparent dielectric permittivity resulting from the calculation of the theoretical hyperbolic time-distance curve was shown. The conditions under which it is impossible to determine the presence of a layer of unfrozen rocks from a hyperbolic time-distance curve are also presented. The established regularities were tested on synthetic georadar radargrams calculated in the gprMax software program. The findings of the theoretical studies were confirmed by the comparison with the results of the analysis of the georadar measurements computer simulation data in the gprMax system (the relative error was less than 0.5%).

Investigation of the mechanical behaviour of frozen fissured sandstone addressing the role of fissure ice

Due to the existence of ice in rock fissures and the complex ice–rock interactions, the exact role of fissure ice in altering the mechanical behaviour of frozen rock mass remains unclear. In this study a series of uniaxial compression experiments were conducted on frozen sandstone samples that bearing precut fissures of different angles at both freezing and room temperatures. The failure process of samples was recorded using a high-speed camera. Besides, a particle flow code-based simulation, addressing the role of fissure ice, was performed. The results indicate that: (1) Freezing does not alter the trend of strength variation concerning the fissure angle, but it does strengthen the samples significantly. (2) At both room and subzero temperatures, the crack initiation mode of the specimens showed a changing trend of "tensile cracking → shear cracking → tensile cracking" as the fissure angle increased. (3) The change in fissure angle leads to a change in the stress state at the fracture end, while the fissure ice, through ice–rock interaction, further alters the fracture's stress state, thereby affecting the initiation and expansion mode of the fracture. Based on the simulation results, three strengthening mechanisms of fissure ice are proposed: (I) under compression, the ice acts as a filling support; (II) the fissure ice shortens the fracture length, resulting in a reduction of the stress intensity factor at the fracture ends; (III) under tensile or shear states, the ice acts as a binder. The above strengthening effects of fissure ice act simultaneously or alternatively at different fissure angles.

Numerical Simulation Study on Blasting-induced Damage Characteristics of Frozen Rock

Rock masses in cold regions are exposed to a negative temperature environment for extended periods, causing significant changes in their mechanical properties. This inevitably results in substantial differences in the blasting characteristics compared to rocks at normal temperatures. To reveal the influence of different temperatures on the blasting characteristics of frozen rocks, this paper utilized a finite element method-based LS-DYNA software for numerical simulation of single borehole blasting at freezing temperatures of -5°C, -10°C, -20°C, and -30°C. The results showed that under negative temperature conditions, the degree of rock blasting-induced damage gradually decreased as the rock temperature decreased. As the temperature decreased from -5°C to -30°C, the volume of rock blasting-induced damage decreased by approximately 14%. Additionally, this paper has further investigated the effects of ignition locations, free surface, and borehole burdens on the blasting-induced damage characteristics of frozen rock. It was found that the volume of the blast cavity is the largest in reverse detonation. While forward detonation is more favorable for damaging the top rock and helps to improve the rock fragmentation at the orifice. Increasing the free surface can significantly improve the effect of blasting-induced damage. There is an optimal borehole burden distance, which can fully utilize the explosive energy and break the rock efficiently. Finally, based on multivariate nonlinear regression analysis, an empirical formula of the reduction coefficient of the specific charge for frozen rock mass is developed, which can provide a theoretical basis for designing and optimizing rock engineering blasting in alpine and cold regions.

The stability issue of fractured rock mass slope under the influences of freeze–thaw cycle

Freeze–thaw failure of frozen rock slope often occurs during engineering construction and mining in cold area, which poses a great threat to engineering construction and people's life safety. The properties of rock mass in cold region will change with the periodic change of temperature, which makes it difficult to accurately evaluate the stability of slope under the action of freeze–thaw cycle by conventional methods. Based on field investigation and literature review, this paper discusses the characteristics of frozen rock mass and the failure mechanism of frozen rock slope, and gives the types and failure modes of frozen rock slope. Then, the research status of frozen rock slope is analyzed. It is pointed out that the failure of frozen rock slope is the result of thermo-hydro-mechanical (THM) coupling. It is considered that freeze–thaw cycle, rainfall infiltration and fracture propagation have significant effects on the stability of frozen rock slope, and numerical simulation is used to demonstrate. The research shows that the safety factor of frozen rock slope changes dynamically with the surface temperature, and the safety factor of slope decreases year by year with the increase of freeze–thaw cycles, and the fracture expansion will significantly reduce the safety factor. Based on the above knowledge, a time-varying evaluation method of frozen rock slope stability based on THM coupling theory is proposed. This paper can deepen scholars' understanding of rock fracture slope in cold area and promote related research work.

Finite Element Analysis for the Mechanism of Stress Wave Propagation and Crack Extension Due to Blasting of a Frozen Rock Mass

The propagation mechanism of explosion stress waves in frozen rock mass is the main factor affecting the blasting efficiency and safety construction of strip mines in alpine cold regions. In order to study explosion stress wave propagation and crack extension in the blasting process of frozen rock mass with ice-filled cracks, RFPA2D is adopted to simulate the influence of the geometric parameters of ice-filled cracks (ice-filled crack thickness d, normal distance R from blasting hole to the ice-filled crack, and ice-filled crack angle α), loading intensity and loading rate on the explosion stress wave propagation effect and the damage range. The results show: The attenuation trend of explosion stress waves decreases gradually with an increase of thickness (e.g., In the case of R is 0.2 m, when d is 0.02 m, 0.04 m, and 0.08 m, the calculated attenuation factor of the minimum principal stress peak value is 7.128%, 18.056%, and 30.035%, respectively), and it decreases slightly with an increase of normal distance and ice-filled crack angle. The damage elements range of the ice-filled crack decreases when the ice-filled crack thickness and normal distance increases. The loading intensity and the loading rate have a significant influence on blasting hole fracture patterns. The ice-filled crack has a guiding effect on the growth of blasting cracks at the blasting hole. Nevertheless, the existence of ice-filled cracks inhibits the propagation of explosion stress waves in frozen rock mass.

Statistical Features of Georadar Signals Obtained by Probing Horizontal Layered Media in Permafrost

Relevance. To study the structure and properties of rock masses in the permafrost zone, such a method of geophysics as ground penetrating radar is successfully used. The existing methods of GPR measurements make it possible to obtain large volumes of reliable data on the layered structure of permafrost rocks. The methodological support for processing and interpreting data is developed much worse. Thus, manual and semi-automatic methods are used to identify the in-phase axes of georadar signals confined to the boundaries of rock layers, which significantly slows down the process of cameral work. Existing methods for automating the selection of in-phase axes of georadar signals do not always successfully cope with this task, since the statistical characteristics of georadar traces obtained by probing a horizontally layered media are very variable. The purpose of the research is to establish the statistical features of georadar signals that form the in-phase axes obtained by probing horizontally layered media in permafrost. Research methods – statistical analysis of the results of field georadar measurements in the Anabar region of the Republic of Sakha (Yakutia) at the site of the Mayat diamond deposit (AO Almazy Anabara) using the GPR OKO ABDL-Triton. Conclusions. The research of the amplitude characteristics of GPR signals that form the in-phase axes showed the presence of a random component, which significantly affects the recorded GPR wave field. Using the results of field measurements of horizontally layered media as an example, a change with increasing depth of the main statistical characteristics, as well as the distribution of amplitude values (normal–uniform–normal) was established. The results obtained will be very useful both in interpreting georadar measurement data and in improving the accuracy of modeling the propagation of ultra-wideband electromagnetic waves in horizontally layered media, and can also be used to refine the previously developed model of a georadar section of a frozen rock mass.

A fully coupled thermo-hydro-mechanical model for fractured rock masses in cold regions

Freezing-thawing disasters are caused by the coupling effect of thermo-hydro-mechanical (THM) activity in rock masses at low temperatures, which seriously threatens the safety of rock mass engineering in cold regions. The accuracy of the coupled THM model is controlled by coupling parameters, such as the migration velocity of unfrozen water, equivalent thermal conductivity, and freezing point. The main difference in the THM coupling process between the frozen rock mass and frozen soil is the anisotropy caused by fractures, and the main difference between the frozen rock mass and normal rock mass is the existence of the ice-water phase transitions. In this paper, the governing equations for THM coupling of fractured rock masses at low temperatures are established, including the mechanical equilibrium equation, continuity equation and energy conservation equation. These equations include the effect of fractures, ice-water phase transitions, water migration and thermal expansion and contraction, which can also be degenerated to equations for rock masses without fractures. Then, the main parameters for the THM analysis are studied. The migration velocity of unfrozen water is closely related to the fractures, temperature, pressure, and phase transitions. Based on the energy conservation law, the expression of the equivalent thermal conductivity is proposed, which is a function of the geometric parameters of fractures, the thermal conductivity of each component, and the content of unfrozen water. Finally, the correctness of the proposed model are validated by Neaupane's experiment and an actual open-pit slope.

Prospects for underground storage of lubricants in the Arctic

Currently, subsoil users in the Far North are faced with serious problems connected with logistics of shipment and storage of high-cube building materials, equipment, lubricants and produced minerals. Lubricants are mostly stored in surface tanks made of steel (or, less often, reinforced concrete). Operation of surface tanks involves some risks governed by evaporation of lubricants in summer period, fire and explosion hazards and loss of sealing of the tanks. In case of damage of steel tanks, lubricants spread over ground surface, and penetrate surface water, soil and air, which has a dramatic environmental impact. Land reclamation and nature recovery take much time (decades) and can be extremely expensive for subsoil users. An alternative to surface storage tanks in the conditions of the Far North can be underground storages arranged in impermeable permafrost rocks. Permafrost rocks represent a cryogenic barrier and eliminate migration of the stored products to the environment. Furthermore, mining industry waste placed in underground storages completely freeze with time and become a part of geological rock mass, which totally eliminates seepage and outlet of waste to ground surface. The underground storages can be mines, boreholes and trenches by type. This article describes the main technological aspects of construction of downhole underground storages which ensure reliable safekeeping of liquid hydrocarbons in frozen rock mass. The economic efficiency of such storages as compared with the surface analogs is briefly proved, the experience of commercial-scale introduction of the downhole storage construction technology is described, and the further routes of the research aimed to enhance efficiency of underground storages in development of remote lands in the permafrost areas are identified. To increase efficiency of this technology, it is proposed to launch R and D work. Finally, the article offers a proposal on construction of underground storages instead of time-worn surface steel tanks in the Far North.

Evolutions of the unfrozen water content of saturated sandstones during freezing process and the freeze-induced damage characteristics

The precise determination of unfrozen water content is of great significance to understand the freezing process of pore water and reveal the freeze-induced damage mechanism for frozen rock mass. In this study, low field nuclear magnetic resonance (LF-NMR) tests were conducted on five types of frozen sandstone samples. The changes in the T2 distribution and unfrozen water content (including unfrozen bound water content and unfrozen movable water content) were obtained and then analyzed. The experimental results indicate that there is little unfrozen movable water exists in the sandstone sample at the temperature of -5 °C and lower, whereas the amount of the unfrozen bound water is slowly decreased during the freezing process. The pore size distribution largely dominates the speed of water-ice phase transition and the total ice volume in the sandstone samples. A larger equivalent average pore radius (rm) leads to a higher speed of water-ice phase transition. The freeze-induced strains of the frozen sandstones were theoretically calculated based on a frost heave model. It is indicated that the freezing strain increases rapidly in the temperature range of 0 °C to -10 °C, while tends to be stable with further decreasing the temperature. Owing to the different pore size distributions, the movable water induces more substantial freezing strain than the bound water in terms of the Wuding sandstone and Linyi sandstone having an rm larger than 1.6 μs. However, it is exactly inverted for the other three sandstones including the Tengchong sandstone, Luzhou sandstone and Zigong sandstone with much smaller rm. The study provides a reasonable method for quantifying the unfrozen water content and freeze-induced strain in frozen rock, as well as important guidance for the design and construction of rock engineering in cold regions.

Investigation and Control of the Blasting-Induced Ground Vibration under Cold Condition

This paper focuses on the investigation and control of the blasting-induced ground vibration under cold condition. The mechanical performance and wave propagation characteristics of the frozen rock mass are quite different from that of the conventional condition. Laboratory tests were implemented to investigate the wave impedance of rock mass in the frozen, saturated, normal, and drying states. Results reveal the longitudinal wave velocity could be enlarged by 40 percent in the frozen state. Then long-term monitoring of blasting vibration was implemented based on the blasting excavation of the Fengman hydropower station reconstruction project in the north of China. Results demonstrate the PPV and frequency both attenuate much slower when the rock mass is frozen, and the obvious turning points of PPV could be found between different temperatures, where the change of the PPV relationship happens. At last, numerical simulation of the blasting seismic wave attenuation and the response in the protected structure was implemented. The equivalent freezing simulation method was proposed and verified with the site experiment data. Results demonstrate that the attenuation coefficient decreases obviously as the frozen depth of the rock mass increases. The dynamic degree response in structure is much stronger and the maximum charge weight per delay was limited more strictly under the frozen condition. A most adverse frozen depth was determined when the charge weight per delay gets the minimum value. With the above control approaches, a total of 676 blasting was completed in Fengman hydropower station reconstruction and no case of excessive measurement could be found.

ОБОСНОВАНИЕ ТЕХНОЛОГИЧЕСКИХ ПАРАМЕТРОВ ТЕРМОМЕТРИЧЕСКОГО КОНТРОЛЯ СОСТОЯНИЯ ЛЕДОПОРОДНОГО ОГРАЖДЕНИЯ

Актуальность исследования обусловлена отсутствием в нормативных документах, регламентирующих выполнение контроля за породным массивом в условиях его искусственного замораживания, единых требований к организации и осуществлению контроля за формированием и состоянием ледопородного ограждения. Цель работы заключается в обосновании оптимальных технологических параметров термометрического контроля ледопородных ограждений строящихся шахтных стволов. Объектами исследования в настоящей работе являются замораживаемый породный массив и система искусственного замораживания. Методы: экспериментальные исследования динамики температуры замораживаемых горных пород, статистическая обработка и анализ экспериментальных данных; математическое моделирование термодинамических процессов, происходящих в условиях искусственного замораживания породного массива. Результаты. Приведены результаты обработки экспериментальных измерений температуры горных пород в контрольно-термических скважинах строящихся шахтных стволов способом искусственного замораживания. На основании обработки и анализа экспериментальных данных установлена закономерность влияния процесса искусственного замораживания на локальные участки породного массива. Проведено исследование влияния расположения контрольно-термической скважины на точность решения обратной задачи Стефана, позволяющей производить корректировку теплофизических свойств породного массива и рассчитывать температурное поле во всем объеме участка замораживаемого массива горных пород. Определено, что термометрическую скважину следует размещать в замковой плоскости ледопородного ограждения в точке с наименьшей температурой. На основе анализа аварийного выхода из строя замораживающих колонок найдено требуемое количество контрольно-термических скважин, которое позволяет обеспечить всесторонний контроль за состоянием ледопородного ограждения. При осуществлении термометрического контроля для установления достоверных параметров ледопородного ограждения и выполнения дальнейшего адекватного моделирования термодинамических процессов, происходящих в замораживаемом породном массиве, выполнено обоснование оптимального расположения и количества контрольно-термических скважин с необходимым пространственным разрешением измерений температуры горных пород по их глубине. По результатам проведенной работы разработана методика выбора технологических параметров способа термометрического контроля ледопородных ограждений шахтных стволов.

Algorithm for processing and interpretation of ground-penetrating radar data in the study of permafrost geocryological structures

Relevance. Ground ice is one of unstable components of the cryolithozone and occupies 400–600 km3 in total. Changes in the conditions of heat transfer of ground ice under the influence of external or internal factors can lead to the formation of thermokarst sinkholes, solifluction mudslides, cryogenic landslides and other dangerous cryogenic phenomena in the frozen rock mass. Various methods are used to study underground ice. You can distinguish the method of GPR. Its advantages are efficiency and high detail of measurements. However, the process of identifying underground ice based on the results of processing and interpreting ground-penetrating radar data is currently not formalized in the form of an algorithm. Purpose of the work. Rapid mapping of geocryological structures requires the development of an appropriate algorithm (sequence of formalized procedures) for the processing and interpretation of ground penetrating radar data. Methodology of the algorithm is based on the analysis of characteristics of GPR traces, the use of fast Fourier transform to calculate the spectra of GPR traces and further analysis of the results. Results of the study. The developed algorithm will make it possible to quickly study the structural features of the frozen rock massif with the release of layer ice. The algorithm was tested on the results of physical and computer modeling of ground-penetrating radar measurements of rock mass with ice included. Conclusions. The use of algorithms for processing and interpretation of ground-penetrating radar data for the operational mapping of geocryological structures of frozen rock massifs makes it possible to reasonably and rationally apply a set of measures to prevent the occurrence of unfavorable geotechnical processes or to reduce economic losses when negative geocryological processes are activated.

Prospecting and Evaluation of Underground Massive Ice by Ground-Penetrating Radar

Data from geocryological studies of soil and rock massifs in permafrost zone are very important as a basis for predicting possible negative consequences associated with climate change. A promising technique for studying geocryological structures (various types of underground ice) is the ground-penetrating radar (GPR) method. This paper presents the applications of the GPR method to prospect and evaluate massive ice in a frozen rock mass. To study the features of GPR signals received during sounding of underground ice, a model of a single GPR trace for the structure “frozen rock-ice-frozen rock” was developed. As a result, regularities were established in the kinematic and dynamic characteristics of GPR signals at the upper and lower boundaries of massive ice, depending on its geometric parameters. The established features were confirmed by the results of computer and physical simulation of GPR measurements of a frozen rock mass model. The main result of the study was to obtain a set of criteria for identifying massive ice according to GPR measurements. The developed criteria will allow the use of GPR for a detailed study of the structure of permafrost rocks to prevent the development of dangerous cryogenic processes in undisturbed and urban areas of the Arctic.

Geological and engineering conditions of deposits as foundation of their safe development

The article studies geological and engineering conditions of the mineral deposits located in cryolithic zone. The demand to study and analyze geological and engineering conditions is justified by safety requirements established to development of the deposits. The article is focused on pebble-phosphate deposit located in Polar Urals. The geological and engineering conditions of this site fall within very severe category, which is connected with endogenetic and exogenic processes of its accumulation. It is the genesis of the deposit that generated the factors that complicate drilling-in conditions, included but not limited to weathering crusts with significant depths and discontinuity, frozen rock mass and its cavernous porosity.

Совершенствование методов прогнозирования состояния ледопородного ограждения строящихся шахтных стволов с использованием распределенных измерений температуры в контрольных скважинах

Development of mineral deposits under complex geological and hydrogeological conditions is often associated with the need to utilize specific approaches to mine shaft construction. The most reliable and universally applicable method of shaft sinking is artificial rock freezing – creation of a frozen wall around the designed mine shaft. Protected by this artificial construction, further mining operations take place. Notably, mining operations are permitted only after a closed-loop frozen section of specified thickness is formed. Beside that, on-line monitoring over the state of frozen rock mass must be organized. The practice of mine construction under complex hydrogeological conditions by means of artificial freezing demonstrates that modern technologies of point-by-point and distributed temperature measurements in test wells do not detect actual frozen wall parameters. Neither do current theoretical models and calculation methods of rock mass thermal behavior under artificial freezing provide an adequate forecast of frozen wall characteristics, if the input data has poor accuracy. The study proposes a monitoring system, which combines test measurements and theoretical calculations of frozen wall parameters. This approach allows to compare experimentally obtained and theoretically calculated rock mass temperatures in test wells and to assess the difference. Basing on this temperature difference, parameters of the mathematical model get adjusted by stating an inverse Stefan problem, its regularization and subsequent numerical solution.

Geocryological exploration of frozen rock mass by nondestructive electromagnetic methods

Geocryological exploration of frozen rock mass by nondestructive electromagnetic methods

FORMATION OF GEOCHEMICAL ANOMALIES IN HYDROCARBON MIGRATION IN THE PERMAFROST ZONE OF WESTERN SIBERIA

Climate warming can be caused by global changes due to emissions of the greenhouse gases, which are mainly carbon dioxide and methane. Although vertical migration of hydrocarbons (seepages) to the surface from oil and gas fields has been known for many years, this important environmental factor has not yet received due attention in the study of the Arctic and Subarctic regions. The major hydrocarbon-induced chemical and mineralogical changes within the permafrost stratum were investigated in the south of theTazPeninsulainWestern Siberia. The samples of frozen core from the deep (35 m) hole, which had been drilled from the top of hydrolaccolite, were examined to analyze the cryogenic texture of the frozen rock mass, to estimate the gas content in rock and ice, and to determine the authigenous mineral association using SEM and EDX spectroscopy analysis. It is shown that the migration of hydrocarbon gases through the permafrost stratum is caused by shear deformations with the formation of cryogenic crack-type textures on the sliding surfaces, which are characterized by the presence of gas-saturated ice crystallites and high jointing of quartz. It has been established that the migration of hydrocarbons, primarily methane, frozen in sedimentary strata causes significant changes of the pH/Eh parameters: local anaerobic conditions may be changed by microaerophilic ones through the formation of oxygen during crystallization of the water in the slide area; mainly neutral and weakly acidic conditions can locally be changed by the alkaline ones due to the cryogenic concentration of chlorides during freezing. It was found that the impulse character of hydrocarbon migration in permeation zones of frozen strata causes mosaic distribution of sulfate and iron reduction processes, which control the neogenesis (including as a result of microbiological processes) of various forms of iron compounds: sulfides – carbonates oxides.

Mechanical properties of frozen rock mass with two diagonal intersected fractures

Based on previous research results, this paper investigated the influence of fracture morphology on mechanical properties and failure modes of rock mass with two diagonal intersected fractures. This study carried out a series of triaxial compression tests on rock-like specimens with two crossed fractures under negative temperature, concluded the following conclusions. The strength and failure modes of rock mass are significantly influenced by the dips of two crossed fractures. The strength of rock mass with two fractures cannot simply be estimated using the method that was developed for the rock mass with a single fracture. When the intersecting angle is less than 30°, the failure plane initiates at the tip of “artificial ruptures” and extends to the upper and lower ends of the specimen. In case of a higher dip and intersecting angle ranging from 30° to 60°, the failure plane propagates along one of these two fractures. The mechanical parameters of rock mass are not only related to the trace length, but also depend on the trace length ratio. One could roughly calculate the strength parameters using the approximation proposed in this paper. For the rock mass with a trace length ratio <0.3 (short trace length/long trace length), the failure mode is dependent on the fracture with a longer trace length. When the trace length becomes significant and the trace length ratio approximates to 1, the failure plane propagates along two fractures, where an X-shaped failure pattern is presented. For the rock mass with moderate fractures and a trace length ratio of approximately 1, the failure mode is independent on fractures, which is similar to the damage pattern of intact rock. The strength and elastic modulus of rock mass decrease with the increase of spacing between fractures, while Poisson's ratio is independent on the spacing. The failure mode can be determined by the area of triangle created by two fractures. Damage occurs at the smaller triangle area first, and propagates with the two sides of the larger triangle.

Frequency-time presentation of georadar profiles based on continuous wavelet transform

The article proposes to estimate electromagnetic energy dissipation in a medium using a new processing method of georadar profiles based on continuous wavelet transform. The proposed method applicability to location of inhomogeneities in a highly electroconductive frozen rock mass is illustrated.

Nouveau coulis à base de ciment pour le scellement d'ancrages dans le roc gelé du Grand Nord

At present time, in frozen rock, the anchors are not grouted with conventional cement grouts as these are inefficient, or deteriorate with the formation of ice lenses during the freezing of the mixing water. The problem is avoided by boring deeper into the rock mass, until the unfrozen horizon is reached, if accessible, or by using thermal protection systems, which result in additional costs. Substantial economies may be obtained by grouting the anchor in the frozen rock, along a length necessary and sufficient to insure the stability of the structure, by using an antifreeze grout with a Portland cement base without resorting to thermal protection. In this context, the results of a study carried out in the Far North are presented, including pull-out tests of anchors grouted with a Portland cement base grout in a rock frozen at −12 °C. The resistance to frost of the cement grout has been achieved by using an antifreeze chemical admixture, the sodium nitrate (NaN02), which has allowed the setting of the anchors without heating the steel bars, the rock, or the grout. The results obtained show that the cement grout used may be considered as an efficient grouting product for the design of grouted anchors in the frozen rock or in the permafrost of the Canadian Far North. Key words: frozen rock mass, permafrost, grouted anchor, pull-out test, Portland cement grout, antifreeze chemical admixture, Canadian Far North, Arctic.