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Статті в журналах з теми "Diverse strength rock"
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Saadati, M., K. Weddfelt, and P. L. Larsson. "A Spherical Indentation Study on the Mechanical Response of Selected Rocks in the Range from Very Hard to Soft with Particular Interest to Drilling Application." Rock Mechanics and Rock Engineering 53, no. 12 (September 12, 2020): 5809–21. http://dx.doi.org/10.1007/s00603-020-02242-9.
Повний текст джерелаАнотація:
AbstractThe focus of this work is toward an investigation of the mechanical response of a variety of rocks to indentation loading as a close condition to drilling application. A rock classification method is introduced based on the mechanical response of the rock when loaded by a spherical indenter. Spherical shape is selected for the indenter as a common geometry, which to some extent represents most of the new or worn inserts in drill bits. Both of the force–penetration and fragmentation responses are studied and the results are categorized accordingly. Indentation loading of a quasi-brittle medium like rock contains a complex three-dimensional stress state, in which the compressive strength, tensile strength, compaction behavior and the brittleness of the rock all together are reflected in its mechanical response. Therefore, depending on the type of the rock and its properties, this response is also very diverse for different rocks. Eight types of rocks are investigated and the results from the force–penetration and fragmentation responses are summarized into three different classes.
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Qiu, Huafu, Fushun Zhang, Lang Liu, Dongzhuang Hou, and Bingbing Tu. "Influencing Factors on Strength of Waste Rock Tailing Cemented Backfill." Geofluids 2020 (October 19, 2020): 1–7. http://dx.doi.org/10.1155/2020/8847623.
Повний текст джерелаАнотація:
Tailing cement filling is an important development direction in mine filling, as it is a green and environmentally friendly method for efficiently treating solid waste in mines. Adding a certain amount of waste rock can effectively improve the backfill strength and better meet the filling strength requirements. To address the use of waste rock tailings in cemented filling materials, a uniaxial compression test was carried out on backfills with different cement/sand ratios and waste rock contents, and the influence of the cement/sand ratio and waste rock content on the strength of the backfill was studied. This study found that when the waste rock content is certain, the strength of the backfill increases with the increase in the cement/sand ratio, and the increase in strength slows with the increase in the cement/sand ratio until the strength of the backfill reaches a limit and no longer increases. When the cement/sand ratio is constant, the strength of the backfill first increases and then decreases as the waste rock content increases. When the cement content is constant, the addition of a certain amount of waste rock reduces the specific surface area of the solid materials in the backfill, increases the amount of cement per unit area, and improves the strength of the backfill. When the waste rock content is too high, due to the large particle size of the waste rock, the tailings cannot completely wrap around the waste rock, resulting in a weakening of the cement in the backfill, which reduces the strength of the backfill. This study found that the waste rock content and the cement/sand ratio in the backfill have a significant impact on backfill damage. The damage is mainly caused by insufficient cement strength. The presence of waste rock will change the original direction of crack propagation, resulting in more crack bifurcation, and the form of the destruction surface on the backfill is complicated and diverse.
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Wu, Zhonghu, Liping Li, Yili Lou, and Wentao Wang. "Energy Evolution Analysis of Coal Fracture Damage Process Based on Digital Image Processing." Applied Sciences 12, no. 8 (April 13, 2022): 3944. http://dx.doi.org/10.3390/app12083944.
Повний текст джерелаАнотація:
Coal rocks often contain calcite, which has a significant effect on the mechanical properties of coal and the energy evolution during rupture damage. In this study, the meso-scale of rock is considered, and the spatial distribution of the internal structure of coal is characterized by digital image technology. Uniaxial compression tests were conducted using RFPA on coal rocks containing calcite veins with diverse dip angles. The research results show that the different azimuth angles of the calcite veins change the internal stress distribution of the coal, resulting in higher coal compressive strength at low dip angles (0°, 15° and 30°). Under high dip angles (45°, 60°, 75° and 90°), coal has lower compressive strength. The fracture mode of coal is significantly affected by calcite. At low dip angle, the fracture mode of coal and rock is complex, which are inclined Z-type (0°), V-type (15°) and inverted V-type (30°), respectively. At high dip angle, the fracture mode of coal and rock is single, which is type I failure mode. The destruction process of coal rocks is influenced by calcite veins. Under low dip angle, the internal stress distribution of coal is relatively uniform, the weak cementation between matrix and calcite vein in coal is not easy to be damaged, the stress required for coal failure is large and the input energy, accumulated elastic energy and impact energy index are large. Under high dip angle, the internal stress distribution of coal is uneven, the weak cementitious material between matrix and calcite vein in coal is easy to be damaged and the input energy, accumulated elastic energy and impact energy index are small.
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Pells, P. J., Z. T. Bieniawski, S. R. Hencher, and S. E. Pells. "Rock quality designation (RQD): time to rest in peace." Canadian Geotechnical Journal 54, no. 6 (June 2017): 825–34. http://dx.doi.org/10.1139/cgj-2016-0012.
Повний текст джерелаАнотація:
Rock quality designation (RQD) was introduced by Don Deere in the mid-1960s as a means of using diamond core to classify rock for engineering purposes. Subsequently, it was incorporated into the rock mass rating (RMR) and Q-system classification methods that, worldwide, now play substantial roles in rock mechanics design, whether for tunnels, foundations, rock slopes or rock excavation. It is shown that a key facet of the definition of RQD is ignored in many parts of the world, and it is noted that there are several inherent limitations to the use of RQD. Based on mapping of rock formations by 17 independent professionals at different locations in Australia and South Africa, it is shown that differences in assessed RQD values result in significant errors in computed RMR and Q ratings, and also in geological strength index (GSI) and mining rock mass rating (MRMR). The introduction of a look-up chart for assessing GSI has effectively removed the need to measure, or estimate, RQD. It has been found that GSI values derived from the look-up chart are as valid as those derived by calculation from the original component parameters, and are satisfactorily consistent between professionals from diverse backgrounds. The look-up charts provide a quick and appropriate means of assessing GSI from exposures. GSI is, in turn, a useful rock mass strength index; one new application is presented for assessing potential erosion of unlined spillways in rock. Incorporation of RQD within the RMR and Q classification systems was a matter of historical development, and its incorporation into rock mass classifications is no longer necessary.
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Fu, Jinwei, Shuli Liu, Lielie Li, and Jianzhou Wang. "A modelling resin material and its application in rock-failure study: Samples with two 3D internal fracture surfaces." Open Geosciences 12, no. 1 (October 28, 2020): 1237–46. http://dx.doi.org/10.1515/geo-2020-0132.
Повний текст джерелаАнотація:
AbstractThe mechanism of fracture propagation, interaction and coalescence inside rock masses is a highly concerned issue in geotechnical engineering. But as it is difficult to manufacture 3D internal pre-fractures and observe directly the failure evolution process inside real rocks or their opaque similar materials, most previous studies have been limited to 2D conditions. The experiment investigation on 3D rock failure is still in a preliminary stage. In this study, a resin material has been developed by extensive formula tries. It is absolutely transparent and the ratio of tension–compression strength (brittleness value) can be 1/6.6 at −10 to −15℃. It is much more brittle and rock-like than analogous materials used by former scholars. A set of preparation, casting mould, and post-processing technologies were established and specimen-making with multiple pre-fractures is enabled. In the designed scheme, specimens are made with two parallel internal fracture surfaces yet of four different stagger separations. Uniaxial tests were carried out and the stress–strain relationship is analysed. It is shown that the specimen has gone through four stages as the traditional rock test before failure. Many diverse forms of secondary fractures, such as wrapping wing crack, petaloid crack, and giant quasi-wrapping fracture surface, which were not found in 2D conditions have appeared and their evolutions were clearly seen in each stage.
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Man, Ke, Ju Wang, and Xiaoli Liu. "Dynamic Tensile Properties of Granite Varied with Depths under a Similar Loading Rate." Advances in Civil Engineering 2018 (November 22, 2018): 1–10. http://dx.doi.org/10.1155/2018/6048312.
Повний текст джерелаАнотація:
Based on the SHPB device, the dynamic tensile test was carried out on the granite, which is located at the depth 350 m∼580 m at the same borehole in TianHu area Xinjiang Province, the preselected site of the high-level radioactive waste geological disposal in China. Under the loading rate level of 105 MPa/s, the dynamic tensile strength is generally between 15 MPa∼35 MPa, which is of significant reference for the site selection. No matter whatever the depth, the dynamic tension strength increases with the loading rate, which shows the loading rate effect of brittle material. Meanwhile, the failure model is also tension pattern, which is the same as the static tension test. Furthermore, as the physical characteristics of the rock have been changed gradually, the rock strength and other mechanical properties will increase or decrease with the depth. From the point of physical mechanism, the density, porosity, and others are different at diverse depths, which lead to the differences of mechanical properties. And the result and the theoretical knowledge could be applied to the blasting and excavation of deep geoengineering and HLW geodisposal.
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Alam, MD Waquar. "Analysis of Load-Bearing Capacity of Initial lining in Tunnels." International Journal for Research in Applied Science and Engineering Technology 9, no. VII (July 31, 2021): 3954–60. http://dx.doi.org/10.22214/ijraset.2021.37092.
Повний текст джерелаАнотація:
Large displacements during excavation are regularly observed in Squeezing ground condition and Rock-burst condition with high overburden. The expected displacement has to be estimated prior to excavation to provide enough allowance for the displacements. The support system need to be well-suited through the estimated imposed strains. As the estimated displacements and thus the strains in the support depend upon the load-bearing capacity of support. The ratio of uniaxial compressive strength of rock mass to maximal insitu stress determines tunnel integrity in the weak region.This ratio estimates the requirements of initial lining to control strain to a stipulated level. The elasto-plastic theory may deliver definitive forecasts providing the strength limitations of rock masses are identified accurately. With the help of empirical analysis, the development of displacements for diverse advance rates and supports can be concluded. As a consequence, a quantitative finite element model based on an advanced built-in model is designed to analyse the load-bearing efficiency of initial lining although taking into consideration the time-dependent and non-linear material behaviour of initial lining. The time-dependent excavation mechanism of the drill-and-blast approach for tunnels guided by full face excavation is considered in the finite element model. The material parameters for the initial lining were computed based on case studies- (A Chibro-Khodri Hydropower Tunnel).
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Kislov, Evgeniy V., and Lyudmila I. Khudyakova. "Yoko–Dovyren Layered Massif: Composition, Mineralization, Overburden and Dump Rock Utilization." Minerals 10, no. 8 (July 30, 2020): 682. http://dx.doi.org/10.3390/min10080682.
Повний текст джерелаАнотація:
Ultramafic–mafic complexes are widely developed in the Earth’s crust. They contain deposits of various minerals. The Yoko–Dovyren intrusive in the North Baikal Region, Russia, is considered an example of an intrusive containing diverse mineralization: Ni-Cu, Platinum group elements, Cr, Zr, B, and blue diopside. During the development of the deposit, a huge amount of magnesium-containing rocks are moved to dumps and have a negative impact on the environment. To minimize this process, overburden and host rocks need to be involved in production, thereby avoiding the movement of rocks into dumps. The construction materials production is main industry using this rocks. Therefore, the purpose of these studies was to determine the quality of magnesium-containing rocks and the possibility of their use in construction. As a result of the complex works performed, it has been determined that these rocks have required physical and mechanical characteristics. Concretes in large and small aggregates from magnesium-containing rocks were obtained. It has been concluded that they are superior to concrete from granite rubble and quartz sand in terms of their strength indicators. The use of magnesium-containing rocks, without allowing them to fall into dumps, will allow us to create clean, environmentally safe mining enterprises.
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Tajduś, Krzysztof, and Antoni Tajduś. "Some Considerations on Horizontal Displacement and Horizontal Displacement Coefficient B." Studia Geotechnica et Mechanica 37, no. 4 (December 1, 2015): 75–82. http://dx.doi.org/10.1515/sgem-2015-0047.
Повний текст джерелаАнотація:
AbstractMining-induced deformations of the ground surface and within the rock mass may pose danger not only for surface constructions but also for underground objects (e.g., tunnels, underground storages, garages), diverse types of pipelines, electric cables, etc. For a proper evaluation of hazard for surface and underground objects, such parameters as horizontal displacement and horizontal deformations, especially their maximum values, are of crucial importance. The paper is an attempt at a critical review of hitherto accomplished studies and state of the art of predicting horizontal displacementu, in particular the coefficientB, whose value allows determination of the value of maximum displacement if the value of maximum slope is known, or the value of maximum deformation if the value of maximum trough slope is recognized. Since the geodesic observations of fully developed subsidence troughs suggest that the value of the coefficient depends on the depthH, radius of main influences rangerand properties of overburden rock, in particular the occurrence of sub-eras Paleogene and Neogene layers (old name: Quaternary and Tertiary) with low strength parameters, therefore a formula is provided in the present paper allowing for the estimation of the influence of those factors on the value of coefficientB.
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Afradi, Alireza, and Siamak Rezazadeh. "Stability Analysis and Support Design of Imam Reza Tunnel in Ardabil Sarcham Road by Numerical Methods." Civil Engineering Journal 4, no. 1 (February 7, 2018): 151. http://dx.doi.org/10.28991/cej-030976.
Повний текст джерелаАнотація:
Geological structures and performance of the geodynamic processes can affect engineering projects on their own. Hence, the stability analysis and designing methods for foreseeing the retaining and support system for tunnels are diverse and came from different points of view. So this study seeks to present stability analysis of Imam Reza tunnel in Ardabil Sarcham Road with a special focus on the impact of future earthquakes on its stability using numerical methods. In this study, first designing and operating the initial structure with the height of 5.5 m and a semi-circular cross section. Secondly, drilling with the height of 3m and the width of 7.34 m and with a rectangle cross section. For stabilization, Rock Mass Rating (RMR) geomechanical classification systems and methods used. At the stabilization level, the materials were examined in laboratory, regarding the properties of sides and roof of the tunnel and pressure on them. The results of physical and mechanical experiments shown that the compressive strength ranged from 400 kg/cm2 to 500 kg/cm2 on average. The elastic modulus is between 12 and 13 GPa for the rocks. The Cohesion (C) ranged from 4-5MPa to 5 MPa and the Angle of Internal Friction (φ) is between 60ᵒ and 50ᵒ.
Дисертації з теми "Diverse strength rock"
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Фролов, Олександр Олександрович. "Керування енергетичними потоками при вибуховому руйнуванні різноміцнісних масивів гірських порід на кар’єрах". Doctoral thesis, Київ, 2013. https://ela.kpi.ua/handle/123456789/7327.
Повний текст джерелаЧастини книг з теми "Diverse strength rock"
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Dunham, John B. "Depositional and diagenetic controls on the mechanical properties of rocks in the Monterey Formation of the Santa Maria Basin, California." In Understanding the Monterey Formation and Similar Biosiliceous Units across Space and Time. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2556(01).
Повний текст джерелаАнотація:
ABSTRACT The Monterey Formation of Central and Southern California has produced billions of barrels of oil since the early 1900s. The Monterey Formation in the Santa Maria Basin is a tectonically fractured reservoir, meaning that the fractures formed through natural geologic processes; they are not human-generated artifacts. Open natural fractures provide the effective porosity for oil storage and the permeability pathways through which oil flows from rocks to wells. Monterey strata are notable for a diverse range of lithologies characterized by contrasts in texture and composition. Not all Monterey rock types contain natural fractures. Structural geologists applied the concepts of mechanical stratigraphy to the Monterey Formation to explain fracture variability. Hard rocks, including chert, porcelanite, and dolostone, contain extensive open-fracture systems, while softer lithologies like siliceous mudstone and organic-rich mudstone have few or no open fractures. However, the words “hard and soft” or “strong and weak” are inexact and subject to interpretation. This report constrains these qualitative descriptions by using engineering-geology data to associate rock properties with quantitative measurements of rock mechanical strength.
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Berger, Antony R. "Introduction." In Geology and Health, edited by H. Catherine W. Skinner. Oxford University Press, 2003. http://dx.doi.org/10.1093/oso/9780195162042.003.0004.
Повний текст джерелаАнотація:
This volume is a contribution to the new and rapidly expanding field of medical geology that links geologists and other earth scientists with plant and animal biologists and medical, dental, and veterinary specialists in efforts to resolve local and global health issues. The topics mentioned range from the health effects of arsenic, mercury, and fibrous minerals, natural hazards that contribute to the etiology of endemic diseases, to questions on the identification of such hazards. Medical geology aims to strengthen and integrate research that can reduce environmental threats to the health and well-being of humans and animals. It embraces disciplines as diverse as mineralogy and pathology (Geology and Health 2001, Geosciences and Human Health 2001). Health generally refers to people and other living creatures, whereas the focus of geology is on the inanimate and the distant past. Although these may be separate arenas or compartments for investigations, the direct links are hard to ignore. Life itself has evolved within a matrix of earth materials — rocks, minerals, soils, water, air — the availability of which has a profound control on what all living creatures ingest and how they develop, both biologically and culturally. The air we breathe, the water we drink, and the nutrients we consume depend on the geological environment that we can only partially control. As we struggle to cope in a world rushing toward 10 billion people, a better understanding of the ways in which the natural environment influences our health should permit more intelligent decisions for the future. The general consensus concerning global change recognizes that humans have had a powerful impact on their surroundings. The other side to that relationship — the sometimes harmful effects of geological materials and processes on us — is the subject of this volume. Combining knowledge and expertise from the earth sciences with that from the medical and life sciences has numerous applications to the resolution of health issues. Coordinating efforts can sharpen the definition of a problem, aid in strategies of reclamation, define and locate sources of potable water, and develop economical solutions based on geological principles that can help to ease, if not prevent, suffering and disease.
Тези доповідей конференцій з теми "Diverse strength rock"
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Scott, Dan E., and Marc R. Skeem. "Diamond Enhanced Shear Cutting Elements on Roller Cone Bits." In ASME 2001 Engineering Technology Conference on Energy. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/etce2001-17031.
Повний текст джерелаАнотація:
Abstract Polycrystalline diamond (PCD) cutters and drag bit designs have been substantially improved since their 1972 introduction, and PCD drill bits now are approaching the rolling cone tungsten carbide insert (TCI) market is terms of revenue size and have surpassed it in terms of economic impact on the drilling industry.1,2 These performance improvements have lead to a significant encroachment into the drill bit market built upon the breakthrough invention of the rolling cone bit by Howard Hughes Sr. Material and design improvements in the last decade, however, have now led to the successful application of patented shear cutting PCD elements as well as conventional diamond enhanced crushing style inserts on rolling cone bits. Diamond enhanced rolling cone bits are also a growth market for diamond elements in drilling. Failing rock in shear is a more efficient process than by crushing, but most cutting materials can not stand up to the forces generated in the shearing process as rock strength increases. To take advantage of the unique ability of the PCD cutter to shear rock efficiently, a concerted R&D effort supported by laboratory and field-testing led to the application of diamond as a shear cutting element on roller cone bits. A variety of rolling cone shear cutting elements have been developed and successfully commercialized in the last decade. This paper will discuss laboratory results and increased field performance achieved relative to conventional crushing style diamond and tungsten carbide inserts. The authors will document through case studies increases in rate of penetration (ROP), footage, overall durability, and gauge holding ability in addition to bearing/seal effectiveness that have further reduced drilling costs and served to increase usage of polycrystalline diamond elements on roller cone bits. These applications range from such diverse markets as high cost offshore North Sea, to low cost North American land operations.
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Zhang, Ruxin, Qinglin Shan, and Wan Cheng. "Near-Wellbore Hydraulic Fracture Non-Planar Propagation and Torturous Morphology in Tight Sandstone Formation." In Offshore Technology Conference. OTC, 2021. http://dx.doi.org/10.4043/31313-ms.
Повний текст джерелаАнотація:
Abstract In this paper, a 3D near-wellbore fracture propagation model is established, integrating five parts: formation stress balance, drilling, casing and cementing, perforating, and fracturing, in order to investigate fracture initiation characteristics, near-wellbore fracture non-planar propagation behavior, and torturous hydraulic fracture morphology for cased and perforated horizontal wellbores in tight sandstone formation. The method is based on the combination of finite element method and post-failure damage mechanism. Finite element method is used to determine the coupling behavior between the pore fluid seepage and rock stress distribution. Post-failure damage mechanism is adopted to test the evolution of hydraulic fractures through simulating rock damage process. Moreover, a user subroutine is introduced to establish the relation between rock strength, permeability, and damage, in order to solve the model. This model could simulate the interaction between fractures during their propagation process because of the stress shadow. The simulation results indicate that each operation could cause redistribution and reorientation of near-wellbore stress. Therefore, it is important to know the real near-wellbore stress distribution that affects near-wellbore fracture initiation and propagation. Initially, hydraulic fractures initiate independently from each perforation and propagate along the direction of maximum horizontal stress. However, hydraulic fractures divert from original direction gradually to interconnect and overlap with each other, because of stress shadow, resulting in non-planar propagation behavior. Individual fractures coalesce into a spiral-shaped fracture morphology. In addition, a longitudinal fracture could be observed because of wellbore effect, which is a result of weak cementing strength or near-wellbore weak plane. Finally, the complex and torturous fracture morphologies are created near the wellbore, incorporating Multi-spiral shaped fracture and horizontal-vertical crossing shaped fracture. However, the propagation behavior of fracture far away from wellbore is controlled by in-situ stress, forming a planar fracture. The highlights of this 3D near-wellbore fracture propagation model are following: 1) it considers near-wellbore stress change caused by each construction to ensure the accuracy of near-wellbore stress distribution; 2) it achieves 3D simulation of fracture initiation and near-wellbore propagation from perforations; 3) the interaction between fractures is involved, resulting in complex and torturous morphology. This model provides the theoretical basis for fracture initiation and propagation, which also could be applied into heterogenous formations considering the effect of discontinuities.