Rock Cavities Research Articles

Моделирование вентиляции угольных шахт с учетом выработанных пространств

Mine ventilation network models are widely used in underground coal mining in Russia. The models cover a variety of practical problems ranging from simple air distribution in active mine workings to changes in the static air pressure gradient associated with complex technological or hazardous processes occurring in mines. Isolated gob areas are integral parts of ventilation networks in coal mines. The most commonly used underground coal extraction technology in Russia is the longwall mining. A gob forms when a coal seam is extracted, and the upper layers of the rock cave in. Gobs are isolated from active mine entries with seals, but there is always air leakages from active faces inducing the air circulation in isolated areas. Gobs join different coal seams and often become the sources of underground fires. Therefore, the inclusion of gobs in mine ventilation network models would help contain accidents and eliminate the caused damage. The study uses the method of representative elementary volumes to incorporate a porous medium into mine ventilation network models. Quadratic resistances are assigned to the edges of the model, where Kirchhoffs laws are valid. The aerodynamic resistances of the gob edges are calculated using the Ergun equation. The proposed method has been used to evaluate pressure gradients in the gob area of the Raspadskaya mine. Several scenarios of the aerodynamic resistance variation in the active mine workings surrounding the gob area, such as partial flooding and drilling of boreholes from the surface, have been simulated, and the corresponding changes in pressure gradients have been analyzed.

Votive Keimelia from Crete: Homeric Perspectives on a 7th-Century Deposit of Curated Objects

Recent excavations at Anavlochos in eastern Crete revealed votive material, consisting mostly of female figurines, deposited in natural rock cavities of a mountain ridge. One cavity stands out from the rest of the deposit for its anomalous finds, which notably include a Minoan sealstone. The various offerings from this "sealstone cavity," all curated objects, were probably deposited in the 7th century b.c. An examination of the use and meaning of curated objects (keimelia) in the Homeric epics shows that they could represent substitutes for a missing person—a possible interpretation for the finds from the sealstone cavity.

INVENTORY AND CHARACTERIZATION OF EROSIVE FORMS IN THE BARBANTIÑO RIVER (MIÑO BASIN, GALICIA, NW PENÍNSULA IBÉRICA)

The existence of forms sculpted by fluvial erosion is frequent in Bedrock Rivers. Since 1999, the Area of Physical Geography of the University of Vigo (Ourense Campus) has been conducting research on these rock cavities in various reaches of the middle Miño River. The exploratory study that is presented corresponds to the case of a section upstream of the Barbantiño river waterfall (Ourense, Galicia). Carried out within the framework of a research line with the objectives of inventorying, characterizing, interpreting and evaluating the erosive forms in the rocky channels of the Miño River and its tributaries, the employed methodology included phases of field work, creation of a database, and statistical analysis. From the records in the sampled sectors of the Barbantiño River, an inventory was made with 60 erosive forms, considering quantitative variables (measurements of length, width, depth) and qualitative variables (morphology of the bottom, state of the walls, and presence of deposits). The preliminary results of the exploratory analysis provide new information on the sculpted forms in bedrock, allowing comparison with previous studies. The erosive forms of the studied section are characterized by great variability in their depth (between 2 cm and 2.7 m), length (between 7 cm and 2.5 m) and width (between 4 cm and 2 m); the strong correlation between surface and bottom dimensions (Spearman's r> 0.85); and the coexistence of cavities in an incipient state, furrows and potholes. These results contribute to the advancement of knowledge of a natural legacy that is part of the geodiversity of the Miño River basin, with a complex of values associated with its condition of geomorphological heritage.

BACKGROUND OF U AND Th IN SEDIMENTS OF BEDROCK RIVERS

The Miño River is a good example of bedrock rivers, where sediment geochemistry is scarcely studied. Its urban reach when passing through the city of Ourense gathers some characteristics that provide interest to its sediments, like scarcity of fine sediments accumulation and the impact of several human activities. Sediments trapped by potholes and other rock cavities were considered. In order to evaluate society-nature interactions through sediment composition it is critical to determine the compositional background (in absence of human alterations), particularly when working with trace elements. This work presents an exploratory assay to determine background in sediments from bedrock rivers by using two uncommon elements, uranium (U) and thorium (Th). To determine their background different statistical techniques were applied in order to set the background composition value and calculate possible enrichments. Background was calculated by simple least squares lineal regression by using Al as independent variable (reference element) resulting in 8.7 mgU kg-1 and 5.6 mgTh kg-1. Enrichments were found in some particular samples and can be attributed to intrinsic microenvironment complexities inside rock cavities.

Sosialisasi pemanfaatan limbah batang pohon pisang Menjadi bahan additive lumpur dan semen pemboran pada masyarakat Desa Pandau Jaya Kecamatan Siak Hulu Kabupaten Kampar

Some people in Pandau Jaya village have banana trees in their yards, but most people throw away the tree trunks after the fruit is harvested, sometimes the banana stems that have been cut down are only used for fertilizer, animal food or left without further exploiting their potential. For this reason, the Service Team conveyed directly to the community that the waste of the banana stems, if collected, could be used as a useful additive for drilling oil wells, although this is the key to the results of tests conducted at the Petroleum Engineering Laboratory, where the additives are obtained from banana trees. has good quality in covering rock cavities, so as to prevent mud loss during the drilling process. The method used in this community service activity is interactive socialization, discussion and question and answer using supporting facilities and directly to the people of Pandau Jaya Village by providing examples of experimental results that have been carried out at the Petroleum Engineering Laboratory. So that the public can know the process of making additives from banana tree trunks and making drilling mud with the use of these additives. If this research can be applied to the oil field, it can increase income for the community.

ADAPTASI KONSEP PURUSA-PRAKERTI PADA PURA DANG KAHYANGAN KAPRUSAN DAN BATU BOLONG DI BATU LAYAR LOMBOK BARAT

This study aims to conduct a study of the adaptation of the purusa-prakerti concept at the Pura Dang Kahyangan, namely Kaprusan and Batu Bolong in Batu Layar District, West Lombok Regency. This study was designed as a qualitative descriptive study in order to describe the concept of purusa-prakerti adapted in Hindu religious temple at Kaprusan and Batu Bolong. Data were collected through observation, interviews and document analysis. This study found that Dang Hyang Nirartha's journey in Lombok built a number of temples as a place to do yoga which is still used as a place to carry out Hindu religious activities. Kaprusan Temple and Batu Bolong Temple are two temples where yoga practice has a special identity, namely adaptation to the purusa-prakerti concept taught in the samkhya darsana system. The Kaprusan temple is cosmologically related to the presence of a burst of sea water hitting the walls of the rock cave which is termed kaprusan as a representation of the phallus (masculine). The phonological dimension gives the meaning of "kaprusan" as a word that is identical to ka-purusa-an. The Hindu community continues to identify the temple that has these characteristics as the “Kaprusan” temple as an adaptation of the Purusa concept. Batu Bolong Temple has an identity related to the presence of a large stone that has a large hole which is identified with yoni (feminine). Judging from the etymology, batu bolong has the meaning of a big stone that has a hole so that it becomes the background for naming the “Batu Bolong” temple which is associated with Samkhya teachings as an adaptation of prakerti.

NOTES ON AN ARTIFICIAL ROOST OF Myotis albescens (CHIROPTERA, VESPERTILIONIDAE) IN SOUTHEASTERN BRAZIL

Myotis albescens has a wide distribution, occurring from southern Mexico to central Argentina and Uruguay, where it is usually caught near streams or flooded areas. M. albescens roosts during the day in cavities such as hollow logs, rock cavities, and buildings. Here, we describe a group of M. albescens roosting in a highway underpass in an Atlantic Forest area in Rancharia, southeastern Brazil. The group was found inside a culvert with a shallow stream passing through it. The animals left the roost and were mist-netted in the first hours of the night. The M. albescens group was composed of 18 individuals, eleven males and seven females. In October, all males had descended testes and two females were pregnant, as confirmed by abdominal palpation. Morphological characters of the specimens fell in the known variation for the species. Our data show that highway underpasses can be important day roosts for bats, especially if riparian areas are preserved

Deterioration and Cavity of Surrounding Rocks at the Bottom of Tunnel Under the Combined Action of Heavy-Haul Load and Groundwater: An Experimental Study

In China, the first tunnel was built in accordance with the 30-ton heavy-haul railway standard. Based on the change in water and soil pressure obtained from long-term on-site monitoring, the cavity mechanism of the surrounding rock at the bottom of a heavy-haul railway tunnel under rich water conditions was explored in this study. The cavity characteristics and degradation depth of the three types of surrounding rock under different axial loads and hydrodynamic pressures were analyzed through laboratory tests. The structural defects at the bottom of the tunnel and local cracks in the surrounding rock were determined to provide a flow channel for groundwater. The dynamic load of heavy-haul trains causes groundwater to exert high hydrodynamic pressure on the fine cracks. The continuous erosion of the bottom surrounding rock leads to a gradual loss of surrounding rock particles, which would further exacerbate with time. The cohesive soil surrounding rock is noticeably affected by the combined action of heavy-haul load and groundwater in the three types of surrounding rock, and the surrounding rock cavity is characterized by overall hanging. In the simulation experiment, the particle loss of the surrounding rock reached 1,445 g, which is 24.2% higher than that of the pebble soil surrounding rock and 40.8% higher than that of sandy soil surrounding rock. The findings of this study could be helpful for developing methods for defect prediction and treatment of heavy-haul railway tunnels.

Stress distribution ahead of mechanized longwall top coal caving face with great cutting height

Longwall Top Coal Caving (LTCC) technology with great cutting height is a new development trend in mining thick coal seam. The cutting height of LTCC face typically ranges from 2.8 m to 3.2 m in many coal mining countvies, but it recently reaches up to 4.2 m in many coal mines in China. Because the cutting height increases, the caving height accordingly decreases that changes the stress distribution around coal face and law of roof rock caving. Based on the geological condition of Longwall 4108 at Ping Shou coal mine, ShanXi province, China, this paper presents a modelling of LTCC mining process with a cutting height of 4.2 m by using the numerical program FLAC3D. From the modelling, the paper presents an analysis of stress distribution ahead of LTCC face with great cutting height. The results show that as the coal face advances, the stress magnitude ahead of coal face increases. The peak front abutment stress moves further away from coal face. The stress concentration ratio increases, and stress concentration zone expands correspondingly. These changes of stress facilitate the failure of top coal, increasing the efficiency of top coal recovery and improving longwall face stability.

The mineral diversity of the Urdini Lakes and the glacial valley of the Urdina River (Rila Mountain) – an overview

An overview of different types of mineralization in the area of the Urdini Lakes and the glacial valley of the Urdina River (northwestern Rila Mountain) has been made. Currently, it is the only protected area for minerals in Bulgaria. In this area, mainly pegmatite, but also skarn and alpine-type mineralizations, have been found to date. Of particular interest are the hybrid desilicified type pegmatites containing emerald, aquamarine and chrysoberyl crystals and the extremely rare native aluminum. The skarn mineralizations from this area are characterized by wollastonite, diopside, garnet (grossular, andradite), zoisite, clinozoisite, scapolite, vesuvianite and others. In the alpine-type mineralizations, well-formed crystals of quartz, adular, epidote and pyrite, as well as nests of almandine with albite, were observed as recrystallization of the minerals previously formed in the cavities of the host rocks. These cavities may also occasionally contain zeolites.

Prauserella cavernicola sp. nov., isolated from cave rock.

A novel actinomycete, designated strain ASG 168T, was isolated from cave rock collected from Stegodon Sea Cave in Thailand. Long chains of non-motile spores that were oval or spherical in shape with a smooth surface developed on aerial mycelia. Substrate mycelia fragmented into irregular rod-shaped elements. A polyphasic taxonomic study showed that strain ASG 168T had typical characteristics of members of the genus Prauserella. 16S rRNA gene sequence analysis indicated that strain ASG 168T shared 97.5 % similarity with Prauserella marina MS498T and 96.7 % with Prauserella coralliicola SCSIO 11529T. Average nucleotide identity values with P. coralliicola SCSIO 11529T and P. marina MS498T were 82.98 and 76.08 %, respectively. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, arabinose and galactose. The predominant menaquinone was MK-9(H4). The predominant fatty acids were iso-C16 : 0, C16 : 0 and summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c). The phospholipid profile consisted of phosphatidylethanolamine, phosphatidylmethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides and two unknown phospholipids. The G+C content of the genomic DNA was 70.6 mol%. Differentiation of strain ASG 168T from closely related species was evident from digital DNA-DNA hybridization values of 29.2 and 21.3 % with P. coralliicola and P. marina, respectively. Based on comparative analysis of phenotypic, chemotaxonomic and genotypic data, the novel actinomycete strain ASG 168T (=TBRC 13679T=NBRC 114887T) is proposed to be the type strain of a novel species, Prauserella cavernicola sp. nov.

Overwinter behavior, movement, and survival in a recently reintroduced, endangered amphibian, Rana muscosa

Basic natural history information is critical for species conservation but is often deficient for endangered species, which can be rare and difficult to study. This is particularly true for behavior and natural history during the winter in temperate regions, when site access can be challenging. For translocation programs in temperate regions, however, winter may be a critical time to assess movement, survival, and threats to persistence in order to understand the causes of translocation failures. Using radiotelemetry, we monitored movement from fall through spring in reintroduced, ex situ bred individuals (N = 21) of the endangered mountain yellow-legged frog (Rana muscosa) to characterize behavior during brumation (overwinter dormancy), overwinter infection prevalence of the fungal pathogen Batrachochytrium dendrobatidis (Bd), and survival. We found that movement rates were variable but low in comparison to other sites. Frogs moved more in the fall when temperatures were warmer in comparison to the winter and spring. However, some frogs still moved (very small distances) even when water temperatures were below 2 °C and snow covered the ground. Frogs were difficult to detect visually, but were almost always in water, including during brumation, when they usually appeared to be in underwater rock caves and crevices in pool habitat. Frogs appeared to be spatially clustered in 3–5 groups throughout the study period and those within a group were often located <1 m from one another. Overwinter survival rates were low: over 70% of animals were confirmed dead, and all were suspected dead by mid-May. While sample size was limited, Bd prevalence and infection intensity increased during the winter and spring, which may have contributed to mortality rates. This study sheds light on a poorly understood life history phase for an endangered amphibian and will inform future management activities to protect this species.

A Quasi-Static Model of Explosive Spherical Charge in Rock and Soil with Impulsive Impedance

The incident wave pressure acting on the wall of the spherical charge in the rock and soil is an important factor affecting the size of the explosion cavity, and the pressure of the incident wave is related to the impedance of both the explosive and the rock and soil. In this paper, based on the quasi-static model of explosive spherical charge in rock and soil, the impact impedance was introduced to calculate the size of explosion cavity in rock and soil medium. Through the field underground explosion experiment, it is found that the calculation result of the impact impedance model is 6.15% higher than the original model, and the influence rule of several geotechnical medium parameters on the cavity size was also analyzed.

Оценка степени техногенного преобразования участка недр при разработке месторождения с обрушением руды и вмещающих пород в восходящем порядке

The study provides a geomechanical assessment of the man-induced transformation of the 1st block at the Kamaganskoye deposit when the mining system is changed to sub-level caving of the ore and host rocks with no possibility of changing the order of reserve extraction. The relevance of the research results from detailed exploration activities that revealed changes in the ore body boundaries and a decrease in the ore grades. The possibility of partial mining of blocks in ore bodies No. 16 and 17 using the ore and host rock caving system has been assessed and the possibility of retaining the upward mining sequence has been established. The sequence of room mining is defined taking into account the changes in the ore body boundaries. The paper presents the results of assessing the stability of the undermined masses of ore bodies No. 16 and 17, as well as the stress-andstrain state of the rock mass at the assumed sequence of room mining. The results of mathematical modeling of the rock mass stress-and-strain state during room mining using the ore and host rocks caving system proved the technical feasibility of this solution.

The Source of Organic Matter and Its Role in Producing Reduced Sulfur for the Giant Sediment-Hosted Jinding Zinc-Lead Deposit, Lanping Basin, Yunnan, Southwest China

Abstract The Jinding deposit, located in the northern part of Lanping basin in southwest China, is the second largest Zn-Pb deposit in China and the third largest Mississippi Valley-type deposit identified globally. The deposit consists of several large tabular orebodies within the Jinding dome. Two stages of sulfide mineralization (sphalerite, galena, and pyrite) are identified, which are mainly hosted in the siliciclastic strata of Early Cretaceous and Paleocene age. The early sulfide minerals are mostly fine grained (&amp;lt;100 μm) and disseminated in the host rocks, whereas the late minerals are ty pically coarse grained (up to 1 mm in diameter) and colloform. It is estimated that about 3.17 × 106 m3 of reduced sulfur (H2S) was involved in the sulfide mineralization of the Jinding deposit, although its origin remains equivocal. Here, we investigate the biomarker signatures of organic matter and the mechanism of generation of the H2S. The organic matter in the Jinding deposit occurs mainly as petroleum filling fractures and cavities in the wall rocks and solid bitumen intergrown with sulfides or calcite. Abundant solid bitumen is also found on the surfaces of the carbonate rocks in the Sanhedong Formation as well as in the rock fractures associated with framboidal pyrite. The petrographic characteristics and maturity-related biomarker parameters show that the solid bitumen in the ores has higher thermal maturity than that in the Sanhedong Formation, suggesting that it was generated at different temperatures in the two settings. The source-related parameters suggest that the solid bitumen in the ores and Sanhedong Formation probably both originated in a mixed marine shale and carbonate environment and that the source rocks for the bitumen precursor were late Triassic marine strata. The δ34S values, ranging from –30 to –10‰ for the fine-grained and disseminated sulfide minerals and from –24.50 to –16.27‰ for the solid bitumen in the early (main) mineralization stage, suggest that H2S was generated by microbial sulfate reduction. We propose that this occurred in the Triassic strata prior to or during migration of hydrocarbons to the Jinding dome to form a H2S-enriched paleo-oil reservoir. This hypothesis is supported by the similarity of the δ34S values (–27.62 to –17.38‰) of solid bitumen in the Sanhedong Formation (the source rocks) to that of bitumen in the ores. The late-ore sulfide, however, displays significantly higher δ34S values, ranging from –8 to 0‰. We propose that the H2S of this stage was mainly generated by thermochemical sulfate reduction as a result of the interaction between hydrocarbons, sulfate, and hydrothermal fluid. The hydrocarbons were oxidized into bitumen that has δ34S values from –7.38 to –4.61‰.

Implicancias tecnológicas del uso del yeso y la cal en el arte rupestre de La Tunita (departamento Ancasti, provincia de Catamarca): aportes a través de la experimentación con mezclas pigmentarias

This paper presents the experimental research carried out in the study of pigmentary mixtures of La Sixtina shelter and El Hornero cave rock art pictographs, located in the sites complex La Tunita (Department Ancasti, Catamarca). The experimentation was tested and carried out with the aim of evaluating previous investigations, characterize materials properties, and tentatively highlight the main characteristics of the chaine operatoire involved in the execution of the large pictographs. Results obtained allowed to establish that the use of local surveyed natural gypsum -or aljez- gives very good workability properties for the execution of large pictographs. Additionally, the use of filler-type materials like calcite and lime is inferred, which in some cases would improve the material cohesion and substrate rocks, respectively. Finally, it was observed that the use of an organic component (cactus slime) added to the pigmentary mixtures would retard the gypsum setting thus improving the workability.

Determination of Biomass Yield and Other Agricultural Characteristics of Switchgrass (Panicum virgatum L.) Varieties in Rainfed Conditions in 4th and 5th Years

Bu çalışma Konya - Karapınar lokasyonunda yağışa bağlı sulamasız şartlarda çok yıllık bir bitki olan altı adet dallı darı çeşidinin plantasyondan sonraki 4. ve 5. yılına ait biyokütle verimi ve diğer özelliklerinin belirlenmesi amacıyla iki yıl süreyle (2018 ve 2019) yürütülmüştür. Tesadüf blokları deneme desenine göre üç tekerrürlü olarak yürütülen çalışmada altı çeşit (Alamo, Shawnee, Kanlow, Shelter, Cave in rock ve Trailblazer) kullanılmıştır. Çalışmada iki yıllık verilere göre yeşil biyokütle verimi 734 kg da-1 (Cave in rock)-1499 kg da-1 (Alamo), kuru biyokütle verimi 343 kg da-1 (Cave in rock)-774 kg da-1 (Trailblazer), bitki boyu 47.8 cm (Cave in rock)- 70 cm (Alamo), metrede sap sayısı 229.8 adet (Cave in rock)- 448.5 adet (Trailblazer), sap ağırlığı 0.78 g (Trailblazer)- 1.24 g (Kanlow), klorofil içeriği % 29.6 (Shawnee)- % 44.3 (Kanlow), stomal iletkenlik 22.4 mmol H2O m -2 s -1 (Shawnee)- 34.3 mmol H2O m-2 s-1 (Alamo) mmol H2O m-2 s-1 ve bitki örtüsü sıcaklığı 37.7 oC (Kanlow) – 43.9 oC (Shawnee) aralığında belirlenmiştir. Çalışmada biyokütle verimlerinin beşinci yılda azaldığı ve Kanlow, Alamo, Trailblazer ile Shelter çeşitlerinin en yüksek verime sahip olduğu belirlenmiştir.

EFFECTS OF DIFFERENT WATER STRESS LEVELS ON BIOMASS YIELD AND AGRONOMIC TRAITS OF SWITCHGRASS (Panicum virgatum L.) CULTIVARS UNDER ARID AND SEMI-ARID CONDITIONS

This study was conducted to determine the effects of different water stress levels on biomass yield, plant height, number of stalks per unit area, single stalk weight, yield reduction ratios and irrigation water use efficiency (IWUE) values of switchgrass (Panicum virgatum L.) cultivars under Central Anatolia conditions. Experiments were conducted for two years (2016 – 2017) in randomized blocks – split plots experimental design with three replications under Konya ecological conditions. Six switchgrass cultivars (Shelter, Alamo, Cave in rock, Shawnee, Kanlow and Trailblazer) and five different irrigation treatments (water stress levels: S1: Full irrigation; S2: 75% of full irrigation; S3: 50% of full irrigation; S4: 25% of full irrigation and S5: Rain-fed without irrigation) were used in present experiments. Kanlow, Alamo and Trailblazer cultivars had greater biomass yields than the other cultivars in all water stress treatments. Under different water stress treatments, dry biomass yields varied between 48300 kg ha-1 (S5- Cave in rock) and 25120 kg ha-1 (S1- Kanlow); plant heights varied between 70 cm (S5) and 180 cm (S1); number of stalks per unit area (meter) varied between 221 (S5) and 356 (S1); stalk weights varied between 0.56 g (S5) and 2.25 g (S1). IWUE was calculated as 5.7 kg m-3 for the first harvest and as 2.1 kg m-3 for the second harvest. Considering the biomass yields from single harvest of rain-fed treatments (S5) and two harvests of the other irrigation treatments (S1-S4), IWUE values and water deficits of the region, it was concluded that single harvest was more suitable for switchgrass plants grown under ecological conditions

Technical and technological support for preventing the destruction of well walls

At present stage of the development of the domestic gas production industry, the problem of increasing the volume of hydrocarbon production is extremely urgent for our state. In the dynamics, there is a significant increase in the volume of directional wells drilling. However, the drilling of such wells is associated with a number of problems. The main problems that may arise in this case are associated with insufficient stability of their bore, which in most cases leads to sticking of the drill string and a significant increase in material costs and production time for their elimination. Therefore, ensuring the integrity of the borehole walls during their drilling is a priority and extremely important problem in the system of measures aimed at improving the quality and improving the technical and economic indicators of their construction. The work is devoted to the improvement of the technology for preventing the destruction of the walls of directional wells, through the influence of technical, technological, mining, and geological factors on the change in the stress-strain state of the mass of the near-wellbore zone of the well. The production material on the sticking of the drill string was analyzed during the construction of wells in the Dnieper-Donets depression fields. It was found that the reasons for the loss of mobility of the drilling tool are mainly the violation of the integrity of the borehole walls as a result of caving and collapse of rocks, as well as the formation of keyseats on the borehole walls. Such complications arose, despite the observance of the operating and technological parameters, when deepening the well and recommendations for reducing keyseats on the walls of the well and preventing caving and collapse of rocks. The existing scientific and practical methods and approaches to prevent the loss of stability of the wellbore walls do not allow eliminating the indicated cause of complications, since the correct selection of the BHA, as well as the development of measures to reduce the intensity of capping and grooving, plays an important role. The paper proposes measures to prevent cavities and keyseats when drilling directional wells. The factors influencing the stability of the borehole walls in conditions prone to collapse and rock caving have been analyzed. The expediency of using baths for strengthening the walls of wells in clayey rocks has been established and substantiated. The formulation of a modified fuel-bitumen bath, the duration of which is 1.5÷5 times longer than that of a fuel-bitumen bath is proposed. A method is proposed for predicting intervals prone to complications associated with the loss of stability of the wellbore walls. According to industrial data, a technology has been proposed for installing a fuel-bitumen bath to prevent keyseats formation during well drilling. To eliminate the keyseats in the well, a bottom-hole assembly is proposed, which consists of stepped heavyweight drill pipes with simultaneous installation of tapered adapters at the transition points from a larger diameter of a drill string element to a smaller one and an eccentric carbide bit

Substantiation of the parameters of open stoping mining method with abandonment of unrecoverable pillars

Relevance. Developing inclined ore bodies of low and uneven thickness using mining systems with caving results in great losses and dilution, deteriorating the conditions for ore gravitation. As a consequence, it becomes necessary to slice the barren rock in the lying side to form slopes with the desired angle. There are also characteristic ore losses at the dead end of the drawing drift independent of the ore body thickness, therefore acquiring a significant role under a lesser thickness. The height of the sublevels, limited by the ore body’s inclination, leads to a considerable amount of preparatory and development operations. The absence of actual in-process monitoring of useful component content in the ore drawing doses often leads to increased dilution rates due to the drawing of barren caved rocks of the previously worked overlying sublevel. Thus, the technological solutions search and their design parameters substantiation for the conditions of inclined ore bodies of low thickness is an urgent scientific and technical problem. Research aim is to substantiate the parameters of the open stoping mining which provides for leaving unrecoverable pillars which ensure the drawing of the maximum volume of pure ore under the cantilever of the hanging side rocks. Research methods. The work used a comprehensive research method based on search and design of technically rational options for geotechnology, their technical and economic assessment and mathematical modeling, and determination of stable parameters of mining system structural elements – the chamber span and the pillar width. Results analysis. The optimal variant of the open stoping mining system has been determined. In comparison with the basic technology of sublevel caving, the specific consumption of preparatory and development operations per 1000 tons of mined ore has been reduced by 34%, the cost of mined ore – by 12%, and ore losses and dilution – by 2 and 2.9 times, respectively. The stable parameters of the chamber span and pillar width have been established. Conclusions. The developed technology of sublevel open stoping with double chambers with frontal ore drawing using remote-controlled loading and hauling machines and subsequent caving of unrecoverable pillars of minimum width allows to significantly increase the efficiency of mining.