The aim of the study has been to define the changes in the physical-mechanical properties of cement stone when adding different-concentration silica fume (SF) of different grades, and to experimentally compare the obtained values with the state standard (GOST) permissible values. Different-concentration cement slurry was mixed, with a 48-hour interval for thickening and solidification before the test. The obtained cement stone was tested for compressive and flexural strength using a hydraulic press; besides, its water separation and spreadability measurements were taken. Based on the experimental data analysis, the dependence of the cement stone’s strength properties on silica fume admixture was defined, and conclusions were drawn on the permissible amount of SF in the cement slurry. With the SF concentration exceeding 8%, the cement slurry no longer meets the standard values and becomes low workable and highly viscous. The article discusses the possibility of improving the cement stone properties in well construction for hydrocarbon deposits development. A series of experiments have been carried out with the purpose to modify the cement of PCT - 1-50 grade with silica fume admixtures of MK-65 and MK-85 grades. The reagent was chosen due to its ability to influence the strength and permeability of the cement stone, as well as the water separation, sulfate resistance, and density of the cement slurry. On the basis of the study done, it has been concluded that the above admixtures do influence the strength properties of the stone; though to increase the flowability of the cement slurry, further experiments are needed. A properly selected admixture can reduce the cement slurry’s viscosity, thereby making it possible to achieve the consistency meeting the production requirements.

In view of the difficult situation in the country in recent years regarding the accumulated environmental damage, including that caused by arsenic-containing waste of mining and processing industry, there is an urgent need to develop a methodology to eliminate the social and environmental consequences of this negative impact. The article presents a study of the soil sorption properties for the Svirsk municipal district that has been long subject to the arsenic waste pollution. In the course of the experiments, the sorption capacity of various soils typical of the examined territory has been defined. The study has shown that among the studied soil types, the dense scaly brownish loamy soils are distinguished as having the highest sorption capacity. The soil with the capacity of 2 to 9 m has proved to be an important geo-ecological barrier prohibiting penetration of arsenic and heavy metals into the underlying aquifers. Using the obtained data, a computer model has been developed with the purpose to predict the arsenic spread in the soil. Based on the research results, the remediation technology for the Svirsk municipal district has been developed. Using the data on various soil types’ sorption capacity and the layer thickness, it is possible to identify the territory zones that have the highest potential for self-conservation i.e. immobilization of mobile arsenic forms in the natural geochemical barrier. The developed model of arsenic migration can be used for predicting the toxicant spread in other regions contaminated with arsenic-containing waste of mining and processing industries.

Walking excavators (ESH) are the main mechanization means when developing coal fields in the regions of Siberia. The operational reliability and in-use performance of overburden dragline excavators determine the mining enterprises’ capacity. The previous studies show that a large percentage of the failures of the mechanical equipment used in opencast mining is connected with the draglines. Reduction of the dynamic load in the kinematic elements of the ESH 20.90 lifting drive increases the operational reliability of the excavators operating in arduous conditions. The statistical analysis has shown that most of the excavators’ breakdowns are connected with the failures of their traction and lifting mechanisms. Therefore, to increase the draglines’ reliability, it is necessary to limit the load on the kinematic elements of the mechanical structure in the periods of the year with a significant temperature gradient. For this purpose, a standard closed-loop control system of the lifting electric drive has been modelled. The modelling has shown an unacceptable level of the dynamic loads arising in the kinematic elements of the excavators operating at low temperatures. As a result, an advanced lifting drive control system for the ESH 20.90 excavator has been developed. The system allows to control the engine torque by the speed, and to stabilize the sustained power of the drive. The study has shown that the suggested system significantly reduces the dynamic stress in the mechanical elements and therefore, increases the excavator’s operational reliability. The application of the developed control system for the lifting drives of dragline excavators has been substantiated.

The aim has been to study the geotechnical conditions of certain ore deposits occurring in a permafrost zone, with the focus on the stress-strain properties of the rocks mass. The study was conducted in 2000-2018 at the Laboratory of Geomechanics and Rock Physics, INRTU. The main physical-mechanical properties of the rocks and ores have been defined in accordance with the requirements of the Russian Federation standards. The characteristics were selected based on the most common methods of estimating the geotechnical conditions of ore deposits, and on the stress-strain calculation for the structural components of the filed development systems. The analysis of the rock stress-strain characteristics has been carried out with the account of the main structural and cryogenic features of the ore deposit rock mass, and of rock outcrop in the mine workings. The study has distinguished three types of geotechnical conditions: permanent-frozen rock zone, frozen-to-thaw rock transition zone, and permanent-thaw rock zone. When evaluating the ore deposit geotechnical conditions, a differentiated approach to determining the rock stress-strain properties is suggested: natural dry state for the permanent-frozen rock zone; water-saturated state after 25 freezing-thawing cycles for the transition zone; natural dry and water-saturated state (depending on the hydrogeological factors) for the permanent-thaw rock zone. It is suggested that the conversion of the sample rock strength properties into those of the rock mass is done using the differentiated coefficient of structural slackening with the account of the permafrost, rock jointing, and the mining’s’ geometrics. When evaluating the burst risk and the brittle fracture susceptibility, the rock cryogenic state should be taken into account. It is recommended that the brittle fracture susceptibility is defined by either of the following methods: by the Kuznetsov criterion (the ratio of the rock’s compressive strength to its tensile strength), by out-of-limit deformation (the ratio of the rock’s modulus of elasticity to its modulus of decrease), or a by combination of the two. Based on the research results, a series of methodological and normative documents have been developed for regulating the rock pressure and defining the geotechnical parameters for the conditions of cryolythozone ore deposits underground mining.

The purpose of the study has been to substantiate, develop and test the methodological, methodical and technological principles of geoinformation mapping for monitoring the geological environment of the Angara water reservoirs. The research methodology is based on the concept of morphosystems that makes it possible to classify the relief and identify its dynamic hierarchy at three levels of generalization: morphostructure, basin, and slope. Based on the shoreline morphosystems maps, a morphodynamic analysis of the shores has been conducted, and the erosion rate has been determined. The information component of the morphosystems mapping is a computerized database containing survey, cartographic, and reference data. The main sources of information are remote sensing and field instrumental observation data from the model sites. The technological component is geoinformation mapping that allows modeling and dynamic analysis of the shoreline morphosystems at different scale and time levels. The ‘reservoir influence zone’ concept has been defined from the point of view of the morphosystems dynamics. For mapping purposes, the reservoir shores have been classified. The potential use of satellite images for decoding the morphosystems has been evaluated. A specific content of the compiled maps has been created. A system of system of notation conventions for the morphosystems’ maps has been developed. Authoring maps of the influence zone morphosystems for the Angara reservoir cascade have been compiled. A method of morphodynamic analysis of the reservoir shores has been developed and tested. The retrospective and prospective morphodynamic analysis of the model sites have defined the erosion rate in the past, present and future. The results of the study infer that based on the geoinformation mapping and morphodynamic analysis of the shoreline morphosystems of the reservoir influence zone, prompt monitoring of the geological environment can be done for large artificial water reservoirs such as the Angara cascade reservoirs.

The purpose of the study has been to create a compact and mobile excavating machine that allows permissible-dilution mining of thin bed strata and seams with different rise angles, and thus, cleaning-up of the mineral reserves both in quarries and underground mines. The article analyzes the known mining machinery and technologies used to extract mineral raw materials from thin bed seams in both opencast and underground mining. Geohods are considered promising mining machines as they make it possible to create significant pressure on the face by using the workings' contour as a support structure for the power loads. The paper presents a geohod structure developed for mining mineral reserves in thin bed ore bodies, and the technology of its application. It is an autonomous device consisting of a frame with guides and hydraulic cylinders, and double disc cutters with supporting sheets and pushers. The double disc cutters of the geohod create pressure on the face due to the frame expansion in the workings, the loosened rock mass being removed with a pneumatic conveying system. Thus, the machine structure is simplified in comparison with the known geohod structures. The power supply and control of the geohod are realized from an external module located on a quarry face or in an underground mine working. The layout of the geohod mill unit allows rectangular cross-section workings, resulting in a high extraction factor. The extraction technology using geohods provides an economic ground for cleaning-up the reserves of thin bed ore bodies.