Papers by Keyword: Rock

Abstract: Abrasive properties of selected rocks and their influence on button bit wear were investigated. Rock samples were obtained from three locations in Southwest, Nigeria. These samples were tested in the laboratory for grain size and circularity factor. Also, porosity, Equivalent Quartz content (EQC), Rock Hardness Number (RHN), Rock Abrasivity Index (RAI) and Uniaxial Compressive Strength were determined. Bit button lengths consumed were measured at regular interval as drilling operation progresses. Results of grain size revealed that medium feldspar granite has least average grain size varying from 0.12 – 0.14 mm. There is possibility that rate of drilling may be low while drilling through this rock. The values of circularity factor varied from 0.624 for medium feldspar granite to 0.786 for coarse muscovite granite. The mean values of porosity varied from between 0.85 and 1.33% for medium feldspar granite and coarse muscovite granite respectively. Biotite hornblende granite has the highest mean uniaxial compressive strength value of 119.48 MPa while coarse muscovite granite has the least mean value of 90.65 MPa. The values of free silica, EQC, RHN, and RAI varied from 35.93 – 51.35%, 45.60 – 67.21%, 575.52 – 821.64 kg/mm³ and 4133.64 – 7003.71 respectively. It was observed that grain size affects the void size in these rocks, which accounted for least porosity value obtained in medium feldspar granite. Average bit button length consumed varied from 15.56 – 24.54 mm for gauge button while length of centre button varied from 13.00 – 19.61 mm. Higher gauge button length consumption could be inferred that it effects the cutting, crushing and wedging of rock mineral components at rock-bit interface. The understanding of grain size, circularity factor and abrasive properties will provide adequate information for quarry to select appropriate bit and drilling machine.

Abstract: The effect of hydraulic fracturing on the permeability and fluid flow of various Iraqi oil storage cores has been studied. Rumaila, Majnoon, and Zubair fields with different permeability were included in this study. Experiments were performed to determine the breaking pressure of the permeable core. Therefore, numerical and experimental results were compared to test the constant pressure on the impermeable core. Finite Volume Method (EbFVM) corresponding to the Dual Porosity Dual Permeability Model (DPDP) was used. A fractured reservoir in the Iraqi fields was studied for its single-phase fluid flow behavior. To represent the pressure distributions, ANSYS-CFX program was used. The comparisons between the fractured and non-fractured cores has been presented. In this paper, the pressure for permeable cores of Rumaila field has been determined and verified during the experimental and numerical simulation due to its lower fracture pressure. Hence, the required pressure has been determined for impermeable cores of Majnoon and Zubair fields due to the difficulties to measure such high pressure. The results show that the expected pressure to make a flow for the core belongs to the Majnoon field reaches to 1.724×107 Pa (2500 psi), while the expected pressure for the fluid to flow into the core belongs to the Zubair field reaches 1.379×108 Pa (20000 psi).

Abstract: In order to study the effect of temperature-confining pressure coupling on the creep behavior of rock-like specimen with precast internal fissures, the creep tests under different temperatures and confining pressures are carried out. The test results show that the rock presents primary creep stage and steady creep stage at low stress levels. Under the condition of high stress, the creep process of rock shows an obvious accelerated creep stage. The curve of accelerated creep stage of rock gradually smoothing with the increase of confining pressure, and the corresponding creep failure time gradually increases. The failure under low confining pressure is mainly tensile failure. The high confining pressure is the shear failure, or even the mixture of shear and plastic failure.

Abstract: The paper considers the current state of the mineral raw material base and the construction material market of the Rostov Region. The effect of various factors on the strain-stress behavior of local limestones has been investigated. The scientific and technical literary sources devoted to the processes of rock failure under various loads have been analyzed. The experimental studies have shown that the tested samples of limestone with a high content of cuboidal grains have characteristics comparable to those of the crushed granite stone. It has been concluded that the use of the Rostov Region limestones in the construction industry is competitive and feasible, provided the proper implementation of the engineering measures proposed in their production.

Abstract: The paper deals with hard cutters of drill bits for drilling rocks. The research on geometry of hard alloy and steel cutters of bits that work either under conditions of shockless loads was carried out in this work. The rationale of tungsten carbide and cobalt composition according to their hardness and robustness is provided. Different alloys were suggested to be used for tools working either under conditions of shockless loads or under shock loads for drilling rocks of high hardness. The rock deformation process was identified to occur by cutting and shearing forces. The highest influence on the cutting process is exerted by the acuity angle and back rake angle. Peculiarities of work of cutters with positive, negative and neutral back rake angles were determined as part of the main research. The dependence of penetration depth on the back rake angle of the cutter was obtained. Indicators of wearing identified in the research are including the type and properties of interacting surfaces characterized by the roughness of cutting bit surface, the hardness of materials in contact zone, friction mode that depends on unit pressure, movement rate, the nature of load application, and the rate of interaction of working parts of bit.

Abstract: The most urgent task in the construction industry today is energy saving at all stages: from the production of building materials, products and structures to the construction of buildings and their operation. Combining these problems forms one of the directions of innovation policy of the majority of subjects of the Russian Federation – strengthening of local capacity and demonstration of solutions to improve energy and resource saving in construction. Building materials industry-one of the leading sectors of the economy, which is quite effectively uses secondary products of many industries for the production of various building materials. Development of production of building materials in this direction is associated with many aspects: the depletion of natural resources, high energy intensity of a number of technological processes of extraction and processing of raw materials; threat to environmental safety of the Russian Federation; lack of waste disposal sites; negative impact on the air, water and plant environment, human and animal health.

Abstract: There is a significant lag in the manufacture of dry plaster and masonry mixtures. One of the reasons constraining this process is the insufficient use of local raw materials and waste of various industries by enterprises of the regions. Experience in the development of zeolite deposits in Russia shows that the exploitation of deposits focused on the use of zeolite-bearing rocks only in traditional areas (agriculture, ecology, sorbents, etc.) with small volumes of production is not enough successful and economically justified. The efficiency of operation of deposits is determined by numerous factors, including the complex use of zeolite-containing rocks. Given that all zeolite-containing rocks can have practical application, it is advisable to provide for the operation of the field of raw materials in the form of an industrial metropolis with the production of a wide range of products.

Abstract: The article consists in the development of compositions of self-compacting powder-activated fine-grained (sand) concrete mixtures, including color ones, for the production of high-density, high-strength and durable architectural and decorative concretes, which do not lose their architectural appeal during long-term operation, on the basis of multi-tonnage waste of stone crushing of various rocks, without the use of expensive mineral reactive components and the study of their physical and technical properties.

Abstract: Drilling and lateral cutting are two cutting modes used by roadheaders in rock cutting. Accurate estimation of the depth of cut (DOC) of the cutterhead of a roadheader is critical for improving the performance and reliabilityofthe roadheader. Some models have been developed for calculating the DOC of a cutterhead in lateral cutting mode. However, an effective method for computing the DOC of a cutterhead in drilling mode is yet to be developed. As thecharacteristicsof the drilling process are significantly different from those of the lateral cutting process, the models developed for calculating the DOC in lateral cutting mode are not suitable for estimating the DOC ofacutterhead indrilling mode. In this study, a quantitative analysis of the DOC in drilling mode is developed via an investigation ofrock breakout patterns. The results show that in anydrilling case, the DOC of the picks on the cylindrical and conical parts of a cutterhead cannot be calculated by using the advance distance per revolution of the cutterhead. The DOC of a pick is affected by the difference between the cutting radii of the pick and its adjacent picks. It is also affected by the interaction between cutting lines. While the distance between two cutting lines in lateral cutting mode is fixed, the distance betweentwo cutting lines inthe drilling mode can vary. The outcome of the studycan help optimisation of cutterhead design and operation.

Abstract: The mechanical response of a middle strength rock, namely Pietra sandstone, is assessed both numerically and experimentally under unconfined compressive loading condition. Two experimental approaches, based on different specimens’ arrangements, have been conducted on Pietra Serena sandstone to determine its unconfined compressive strength (UCS). This parameter greatly influences the boreability of rocks and a precise method for obtaining this parameter is thus always required. The experimental tests have been replicated in LS-DYNA in conjunction with an advanced material model, called the Karagozian and Case Concrete (KCC) model, to benchmark the results and, therefore, to conclude which experimental approaches yield the most reliable results.