Journal articles: 'Rock cuts' – Grafiati (2024)

Abstract:

The selection of the cutter type is of crucial importance to maximise the advantages of mechanical rock excavation systems. Specific energy (SE), cutter forces, and rock properties are used to decide what type of cutter is most suitable for economical excavation of the rock based on laboratory rock cutting tests. This study is concerned with the preliminary results of an ongoing rock cutting program in which a mini-disc has been compared with a point-attack pick in laboratory linear cutting tests simulating a cutterhead on a Helidon sandstone block. Analysis of the preliminary results has shown that the mini-disc experienced lower mean cutting forces and was seven times more efficient than the pick in first layer cuts. However, the mini-disc had mean normal forces 1.5 times higher than the pick. Additionally, first layer cuts taken on the trimmed surfaces required more forces and SE than completely relieved cuts in pick cutting.

Abstract:

The Konawe region is part of the Sulawesi Southeast Arm ophiolite belt where ultramafic rocks are exposed in the form of dunite and peridotite. The formation of nickel deposits is closely related to the weathering process of ultramafic rocks as a source rock. Ultramafic rocks exposed to the surface will experience weathering which is influenced by many factors, including in the form of climate change, topography, and existing geological structures. The weathering process in the source rock can influence variations in chemical elements and magnetic properties in laterite soil profiles. For example, the chemical weathering might affect magnetic mineralogy and the physical weathering could affect granulometry as well as the quantity of magnetic minerals in the soil. Condition of weathering of ultramafic rocks (initial, moderate and advanced) can affect nickel content in laterite sediments. The weathering profile study of serpentine mineral is an indication of the lateralization process that occurs in ultramafic rocks and is carried out through petrographic analysis of thin cuts and polish cuts. Determination of weathering level like this is based on the level of weathering of the mineral serpentine. In this study, the determination of the weathering level of ultramafic rocks (initial, moderate, and continued) uses magnetic susceptibility parameter. A total of 232 ultramafic rock core samples obtained from 34 hand samples were taken from different places and weathered levels were analyzed. The results of the research have shown that the magnetic susceptibility of ultramafic rocks in the study area varies, from 580 x 10-6 SI to 4.724 x 10-6 SI. Based on the value of magnetic susceptibility, magnetic minerals contained in ultramafic rock samples are hematite and geotite minerals. This means that the weathering level of ultramafic rock samples is the continued weathering level. The level of continued weathering that occurs in ultramafic rocks in the study area produces nickel laterite deposits with a nickel content of 1.65 - 2.40% in the saprolite zone, 0.42% in the saprock zone, and 0.20 - 0.51% in the basic rock zone (bedrock).

Abstract:

The topples exposed in the road cut along Highway 16, 17 km west of Jasper, Alberta, were caused by slope steepening by both glaciation and excavation. The toppling of layers that underdip the cut slope was initiated by water pressure, ice pressure, and loose materials in the cracks of rock masses with large block ratios. Toppling formed well-exposed sliding surfaces on steep slopes and rupture surfaces on shallower slopes. Key words : rock slopes, rock cuts, Rockies, toppling, sliding, underdip slopes.

Abstract:

The rock-cut churches of Ethiopia have long intrigued visitors and historians – and have frustrated archaeologists seeking their sequence of construction. Do they belong to one grand ceremonial monastic plan, or a long-lived ritual centre, continually refashioned over time? Since the churches are cut into live rock, the conventional signals of archaeological phasing are hard to find. The authors address these problems at the famous site of Lalibela, showing that, embedded in the cuts and openings, the spoil heaps, and even in the now vanished sediments, the stratigraphic sequence is there to be read.

Abstract:

The road-cuts and other new excavation works provide an excellent opportunity for upgrading the geological maps in Poland. Such opportunity should not be missed. Updating The Detailed Geological Map of Poland at the scale of 1:50 000 should be the priority. Ephemeral nature of the freshly cut outcrops makes this research rather urgent. It would require an adequate planning and organization. Geological mapping based on the new road-cuts and rock sections exposed by new investments should be one of the main tasks of the Geological Survey of Poland.

Abstract:

The road that crosses the Haibat Sultan Mountain in the northern part of Iraq; is one of the dangerous roads in this region. To perform a slope stability analysis for the dangerous parts of the road, we have used Bejerman’s Method. We have reviewed satellite images of the road and all those potential areas were checked in the field; accordingly, eleven stations were recognized. Landslide Possibility Index was determined at the studied stations following Bejerman’s field method. The road climbs the southern face (dip slope) of the mountain through very hard carbonate rocks of the Pila Spi Formation, where the bedding planes daylight in the slope face near the road cuts. This produced many large landslides. Along the northern face of the mountain, the road runs through soft clastic rocks where joint planes in the rock mass intersect and daylight in the slope face near the road cut. In order to prevent future wedge failures, a 30 m offset was created from the toe of the slope to the road. In almost all cases, the Landslide Possibility Index indicated a moderate to very high likelihood for failure along all road cuts.

Abstract:

The Coney Head Complex, White Bay, Newfoundland, comprises allochthonous plutonic rocks and deformed equivalents emplaced over the continental margin during the Ordovician Taconic Orogeny. A U/Pb zircon age of 474 + 2 Ma for tonalite considered as having formed by partial melting in an island arc, indicates that it crystallized in Arenig time. A microgranite dated by U/Pb (zircon + titanite) at 432 ± 2 Ma cuts the tonalite Inherited Proterozoic zircon in the microgranite indicates that the rock formed from magma generated in part by melting of continental crust or sediments derived from such crust. These relationships indicate that the microgranite was emplaced in Silurian time, after Ordovician transport of the tonalite above a continental substrate.

Abstract:

This paper examines the magnitude and distribution of earth pressure on the support systems of open cuts in jointed rock masses. A physical model test was carried out using concrete blocks with man-made joints to represent a jointed rock mass. The model test was simulated numerically to provide a justifiable basis for extended numerical parametric studies. This study focused on the overall procedures of the physical model test, its numerical simulation, and extended numerical parametric studies. A comparison of the results from both the physical model test and numerical simulation confirmed that the applied numerical approach and methodology were suitable for further extended numerical parametric studies. The controlled parameters were the different rock types and joint characteristics including joint shear condition, joint spacing, and joint inclination angle. Results of the earth pressures from the numerical parametric tests in jointed rock masses were compared with Peck’s empirical earth pressure for soil ground. The comparison showed that the earth pressure in jointed rock masses can be very different from that in the soil ground. Accordingly, the effect of the rock types and joint characteristics needs to be considered when designing excavation support systems in jointed rock masses.

Abstract:

In order to resolve the supporting problems of the open-off cuts with span of 10m in Tashan coal mine No.3~5 coal seams, this study investigated and analyzed the problems in the current open-off cuts supporting and the supporting parameters, and performed laboratory test and analysis to the coal and rock's mechanical properties. The open-off cut wall rock in Tashan mine has the problem of serious deformation and high possibility of sudden falling. After academic analysis and numerical calculation, a new supporting mode is designed for the supporting of large span open-off cuts: unite high strength anchor bar, combined anchor rope, W steel strip, metal mesh and concrete to form a group anchor seal effect, therefore maintain the tunnel wall rock's stability and safety. Engineering test was conducted at the 8105 working face open-off cuts, the anchor rope's anchorage force changes in the range of 140 ~ 160kN, the maximum delaminating value of the roof in anchorage zone is about 7mm, and the maximum roof-to-floor convergence is 38mm. The result shows that the proposed "anchor bar - combined anchor rope - concrete" supporting model improved the overall bearing capacity of the supporting structure, controlled the tunnel wall rock's deformation effectively, and also achieved the desired effect of the supporting design, ensured the safety of the large section open-off cuts.

Abstract:

This paper investigates the magnitude and distribution of earth pressure on a support system in open cuts in jointed rock mass for the safer and more economical design and construction of earth-retaining structures installed in a rock stratum. The paper first investigates the limitations of previous research on earth pressure and then addresses them to provide a numerical parametric study based on the discrete element method, which can consider the joint characteristics of a rock stratum. The controlled parameters include rock type, joint conditions (shear strength and angle of joints), and wall type. The magnitude and distribution of earth pressure are investigated based on interactions between the ground and the retaining structure. In addition, earth pressure in the rock stratum is compared with Peck's earth pressure for soil ground. The results indicate that the magnitude and distribution of earth pressure in jointed rock mass are strongly influenced by rock type, joint conditions, and wall type, and that this pressure can be very different from that in soil ground. Furthermore, the results of numerical tests are compared with field measurements, and the comparison shows a reasonable agreement. This paper provides useful data for the assessment of earth pressure in designing support systems for jointed rock mass.

Abstract:

The potential for conventional and/or unconventional hydrocarbon exploration requires the presence of organic-rich, thermally mature rock units containing oil or gas-prone kerogen. Thick black, organic rich shale intervals are well exposed along roadside cuts and river banks at several localities in the eastern part of the Mamfe Basin. Earlier described as anoxic lake bottom deposits, these fine grained rocks constitute the probable pod of active source rock in this basin and belonging to the middle stratigraphic unit of the three that make up the basin’s sedimentary fill. Samples collected from representative outcrop sections (Etoko mile 21, Bachuo Ntai, and Satom Bridge) in the study area were subjected to geochemical analytic techniques; Total Organic Carbon (TOC), Rock-Eval Pyrolysis and Vitrinite reflectance (%Ro) values were calculated. TOC data obtained range from 1.06% to 16.10% indicating good to excellent hydrocarbon generative potentials, Rock-Eval Pyrolysis data plotted along Kerogen Types I, II and III with oil and gas generative potentials. 4 out of 9 samples fall within the oil window from the calculated %Ro while temperatures corresponding to the peak of kerogen pyrolysis (Tmax) and Production Index (PI) for the 9 samples range from 398oC to 463oC indicating that the organic matter (OM) are immature to post mature.The black shale unit of this part of the basin therefore contains very high amounts of good to excellent quality of thermally matured organic matter which can produce and expel oil and gas respectively.

Abstract:

In this work, the material composition of the ore of the Karamola Deposit is studied. A sample of manganese ore from the Karamola Deposit with a size of 0-120 mm was received for research on the material composition. The manganese mineralization of the sample is represented by the mineral series polyanite-pyrolusite and WADA-psilomelane. Mineral secretions are crystalline earthy structures and mixed formations. Manganese oxides are distributed almost throughout the entire mass of the rock. They are represented by crystallized gel formations, soot, and skeletal structures. Ore gels permeate the rock through cracks, cleavages, leaching voids, pores, cleavage planes and penetrate between the scales of layered minerals and form a variety of forms in the mass of the rock: individual strokes, thread-like cuts, veins, edges, layers, nests. Replacement solutions are siliceous or manganese-siliceous in nature and color the rock in the corresponding color with mineral microparticles: black – manganese, red and red – iron. Rock-forming minerals are mainly represented by quartz. The granulometric composition of an ore sample crushed to the minus 2.0+0 mm class was determined.

Abstract:

Understanding the magmatic evolution of the rocks once comprising the hinterland of the Grenville Orogen through their Mesoproterozoic formation is a key to understanding the Grenvillian Orogeny as a whole. In this contribution, we present high-precision isotope dilution thermal ionization mass spectrometry (ID–TIMS) U–Pb and coupled solution multicollector inductively coupled plasma mass spectrometry (S–MC–ICP–MS) Lu–Hf zircon data from magmatic rocks occurring in the allochthonous belt of the Grenville Orogen in the central part of the Grenville Province. We document the presence of a large tract of Pinwarian crust represented by a 1497 ± 5 Ma granitic gneiss, as well as large late Geon 14 to early Geon 13 (1434 +7/−11, 1413 ± 12, 1393 ± 8, 1383 ± 1 Ma) magmatic complexes. One Grenvillian plutonic suite of 1015 ± 2 Ma that cross-cuts the host-rock metamorphic fabric has also been dated. This age provides a minimum age of Ottawan metamorphism in the region. The Hf-isotopic data show that the magmatic rocks of Geons 14 and 13 had mixed mantle and crustal sources compatible with intrusion in a supra-subduction setting as is also supported by the whole-rock geochemical data presented. Emplacement of the magmatic rocks occurred in settings varying from a distal margin arc to a contractional and extensional continental arc. Grenvillian-aged magmatism is more ambiguous, but our data indicate that rocks as young as ca. 1015 Ma may have formed in an ensialic setting.

Abstract:

Coulomb's trial wedge method for estimating the active force on retaining walls is applied to situations where there are steep slopes at limiting equilibrium behind the walls. The analysis is applied initially to slopes of dry cohesionless material; in this case the slope angle is equal to the friction angle of the material. The analysis produces two interesting, and perhaps surprising, results. The first is that the critical wedge angle equals the slope angle, and the critical wedge becomes a "slab" extending an unlimited distance up the slope above the wall. The second is that as the inclination of the slope and friction angle (which are equal) increase the active force on the wall decreases. The method is then applied to more general slopes involving cohesion, friction, and seepage. Back-analysis is first used to obtain combinations of cohesion and friction corresponding to limiting equilibrium; these are then used in the wedge analysis. The results obtained are similar to those for the dry cohesionless slope. The method provides a means of estimating required retaining forces for cuts made in steep slopes of residual soil or partly weathered rock where estimation of strength parameters is often very difficult.Key words: slopes, steep, back-analysis, Coulomb, wedge, analysis.

Abstract:

Conducted a statistic research of the construction features of heading-and-winning machine actuator members for the extraction of potash ores. It is shown that increasing the efficiency of the destruction process of a potash massif with the cutters of heading-and-winning machine actuator members is possible by means of the potential cross-cutting technique. The methods of potash layers destruction by cross cuts were considered. Designs of the heading-and-winning machine actuator members that implement the cross-cutting scheme of potash massif are presented.

Abstract:

Laboratory rock cutting tests are commonly used for the study of the cutting process and the evaluation of the expected performance of excavation machines. The cutting process is dominated by a great number of parameters, most of them relating with the intrinsic mechanical characteristics of the rock. In this study the open software Yade is used for simulating laboratory cutting tests on sandstone samples using a drag pick as the cutting tool. The process is simulated based on a conventional formulation, combined with an enhancement of the sample microstructure through the manipulation of the interaction range coefficient, which provides for the sample a very realistic initial strength ratio UCS/UTS. On cylindrical samples, four different cuts in four different paths were carried out. The mean cutting force for each cut was calculated and was chosen to represent the macroscopic response of the numerical model. The optimum set of microparameters is obtained through an experimental design with the Placket-Burman and Central Composite Design methods, and then optimized, in regard to the microparameters’ values, so that the rock cutting simulation is in close accordance with the observations from the actual laboratory cutting tests.

Abstract:

What if the children "forget" the heritage language? This testimony by Dorothy Begay, a grandmother and long-time resident of the Navajo community of Rough Rock, Arizona cuts to the heart of language planning issues in Native American communities. Her statement also captures the enormity of the task at hand: With the penetration of English into public and private domains so seemingly complete, can a stable balance between the heritage language and English be achieved?

Abstract:

Rocks falling under the category of bimrocks are common in Nepal and are covering large areas of the country. However, knowledge on their exact distribution is limited, and data on classification and quantification of engineering properties are practically nonexistent. So far, the bimrock terminology is not commonly used for engineering classification of rocks in Nepal. However, three types of bimrocks can be identified in Nepal, they are: cataclastic or shear zone bimrocks, conglomeratic bimrocks and the bimrocks produced by weathering. The thickness of the bimrock strata varies according to the geological and tectonic settings and can reach several kilometres. Due to the relative weakness of bimrocks and the high erodability, they can pose serious problems such as excessive overbreak, water inflow and large rock mass deformations in tunnelling, and slope instabilities in road cuts and other excavations for surface structures. Efforts on the study of bimrocks in Nepal are initiated recently and is considered to help identifying, addressing and solving the associated problems.

Abstract:

Abstract Rockfall hazard from cut slopes along highways are caused primarily by unfavorable orientations of discontinuities, presence of unconsolidated cobble/boulder deposits, undercutting of strong rocks by weaker rocks, or degradation of weak rock masses. The rockfall hazard rating system (RHRS) was introduced in Oregon to evaluate the hazard and associated risk to an adjacent transportation facility for a cut slope's potential for releasing rockfalls. RHRS is a numerical score–based rating of parameters that characterize rockfalls. The parameters include slope geometry (height, angle, roughness, orientation), geologic information (discontinuity characterization, undercutting susceptibility), driver's line of sight, and climate. Geologic information, such as discontinuity orientation data, is traditionally collected using a transit compass and measuring tape at the site. The method is time consuming and expensive and can be dangerous. This study tests the use of Google Earth and Google Street View tools to remotely collect data for selected parameters that characterize rockfall hazard. The selected parameters are categorized under slope profile, geologic characteristics, and impact factor parameters, which are quantitatively and qualitatively measurable using Google Street View and Google Earth. A section of U.S. 33 with a high density of road cuts and two more sites along Interstate 64, all located in Virginia, were selected for the study. Sites were evaluated by using a combination of measurement tools available in Google Earth and a visual inspection of the rock units in Google Street View. The results of seven of the sites were re-evaluated using field-derived data.

Abstract:

This paper presents a numerical study on the mechanical behavior of the jointed rocks around the underground opening. By comparing different obliquities and the different locations of the joint, its controlling effect on stability of surrounding rock is evaluated in terms of the shear stress distribution, displacement distribution and the plastic zone pattern, which are induced by underground excavation. The results clearly indicate that, the maximum shear stress occurs mainly near the corner of the opening and the joint plane. When the joint inclination angle is less than 60º, the maximum vertical displacements occur where the joint locates near the skewback. Once the joint inclination angle reaches at 75º, the maximum vertical displacements occur where the joint is through the cross section of the underground opening. The plastic zone reaches minimum at the joint inclination angle of 45º where the joint locates either near the skewback or near spandrel of the opening, while it reaches minimum at the joint inclination angle of 60º where the joint cuts through the cross section of the opening.

Abstract:

Abstract The key working process carried out by roadheaders is rock mining. For this reason, the mathematical modelling of the mining process is underlying the prediction of a dynamic load on the main components of a roadheader, the prediction of power demand for rock cutting with given properties or the prediction of energy consumption of this process. The theoretical and experimental investigations conducted point out – especially in relation to the technical parameters of roadheaders used these days in underground mining and their operating conditions – that the mathematical models of the process employed to date have many limitations, and in many cases the results obtained using such models deviate largely from the reality. This is due to the fact that certain factors strongly influencing cutting process progress have not been considered at the modelling stage, or have been approached in an oversimplified fashion. The article presents a new model of a rock cutting process using conical picks of cutting heads of boom-type roadheaders. An important novelty with respect to the models applied to date is, firstly, that the actual shape of cuts has been modelled with such shape resulting from the geometry of the currently used conical picks, and, secondly, variations in the depth of cuts in the cutting path of individual picks have been considered with such variations resulting from the picks’ kinematics during the advancement of transverse cutting heads parallel to the floor surface. The work presents examples of simulation results for mining with a roadheader’s transverse head equipped with 80 conical picks and compares them with the outcomes obtained using the existing model.

Abstract:

Abstract. Darley Dale and Pennant sandstones were tested under conditions of both axisymmetric shortening and extension normal to bedding. These are the two extremes of loading under polyaxial stress conditions. Failure under generalized stress conditions can be predicted from the Mohr–Coulomb failure criterion under axisymmetric shortening conditions, provided the best form of polyaxial failure criterion is known. The sandstone data are best reconciled using the Mogi (1967) empirical criterion. Fault plane orientations produced vary greatly with respect to the maximum compressive stress direction in the two loading configurations. The normals to the Mohr–Coulomb failure envelopes do not predict the orientations of the fault planes eventually produced. Frictional sliding on variously inclined saw cuts and failure surfaces produced in intact rock samples was also investigated. Friction coefficient is not affected by fault plane orientation in a given loading configuration, but friction coefficients in extension were systematically lower than in compression for both rock types. Friction data for these and other porous sandstones accord well with the Byerlee (1978) generalization about rock friction being largely independent of rock type. For engineering and geodynamic modelling purposes, the stress-state-dependent friction coefficient should be used for sandstones, but it is not known to what extent this might apply to other rock types.

Abstract:

Rock-art, despite much ingenious effort (e.g., among many, Watchman et al. 1997), remains difficult to date by absolute methods, so relative dating has a central importance much as applied to dirt archaeology in the era before routine radiometric dating. It is sound relative dating which will show just what the entities are to which absolute dates may be connected. The first basis for relative dating is the determination of sequence: what motifs done by which techniques in which materials precede and follow each other; and the first basis for sequence is physical superposition, in which one figure plainly overlies another or - in the case of rock-engravings - one figure clearly cuts through another. But often figures do not cut or superpose each other so no relation of sequence exists: and sometimes figures are cut through each other without sequence being clear, or are so much overpainted that the older figures are impossible to discern.

Abstract:

The Litchfield pluton is a poorly exposed 7 km2 composite alkalic intrusive complex that cuts previously deformed and metamorphosed Silurian turbidites in south-central Maine. The pluton includes a variety of alkaline syenites, including the type locality of “litchfieldite”, a coarse-grained cancrinite, sodalite, and lepidomelane bearing nepheline syenite first recognized over 150 years ago and common in many petrologic collections. A new U-Pb zircon age of 321 ± 2 Ma from the nepheline syenite is interpreted to represent the crystallization age of the plutonic complex. A new biotite 40Ar/39Ar age of 239 ± 1 Ma from the syenite is similar to previously published mica ages from the surrounding country rocks and dates the time of regional cooling in the area below ~ 300°C. Whole rock geochemical analyses from rocks of the Litchfield pluton are compatible with strongly alkaline A-type granitoid rocks that formed in a within plate or continental rift tectonic setting. The age and geochemical characteristics of the alkalic igneous rocks near Litchfield are consistent with a model that invokes the generation of a small volume of alkalic magma beneath south-central Maine during a period of Carboniferous transcurrent tectonism in the northern Appalachian orogen.

Abstract:

The ANSYS/LS-DYNA software has been used in this paper to establish the coal rock coupling model. A dynamic simulation of the cutting process was used to analyze the variation of the load. Based on the dynamic analysis of the coal and rock that were cut by the spiral drum, the stress cloud diagram of the coupled model of the spiral drum and the coal and the plastic domain evolution law of the coal and the rock were obtained from the coal to the rock. The time history curves of the parameters, such as the stress and strain of the drum and the pick, were obtained, and the stress distribution of the spiral drum during the working process was ascertained. The results showed that when the spiral drum cuts the interface between the coal and the rock, the coal and the rock collapsed and the working load fluctuated. Changing the traction speed in order to change the rotational speed of the drum had a more obvious effect on the load and the stress on the drum. Through the use of simulation, the stress distribution cloud diagram of the drum was obtained. The study has shown that the stress on the end plate was significantly higher than that on the cutting blade. The maximum stress acting on the alloy head was 1209.26 MPa. This study has provided a basis for the design and optimization of the drum with regard to reliability.

Abstract:

A continuous miner is one of wall mechanized coal face; its design quality and performance have directly effect on coal productivity and economic benefits. A pick on a continuous miner, contacting with coal and rock, is a tool cutting directly coal and rock, its force condition during it cuts determines directly loads of the cutting mechanism, pick wear and tear, fabric vibration and cutting performance of the machine, is the basis for the design of a continuous miner. By considering a variety of factors, a mathematical model, including the coal and rock properties, structural parameters of a pick, pick sequence, cutting parameters of the continuous miner, is established in the paper, visualization software which can be directly reflected pick' forces on the continuous miner is design. On this basis, pick' forces of a continuous miner under different working conditions are simulated and studied, which create conditions for understanding pick' force during cutting process of a continuous miner, computer-aided design of the cutting mechanism, dynamic design and research of the machine.

Abstract:

Abstract. Results of examination of experimental data on non-linear elasticity of rocks using experimentally determined pressure dependences of P- and S-wave velocities from various literature sources are presented. Overall, over 90 rock samples are considered. Interpretation of the data is performed using an effective-medium description in which cracks are considered as compliant defects with explicitly introduced shear and normal compliances without specifying a particular crack model with an a priori given ratio of the compliances. Comparison with the experimental data indicated abundance (∼ 80 %) of cracks with the normal-to-shear compliance ratios that significantly exceed the values typical of conventionally used crack models (such as penny-shaped cuts or thin ellipsoidal cracks). Correspondingly, rocks with such cracks demonstrate a strongly decreased Poisson ratio including a significant (∼ 45 %) portion of rocks exhibiting negative Poisson ratios at lower pressures, for which the concentration of not yet closed cracks is maximal. The obtained results indicate the necessity for further development of crack models to account for the revealed numerous examples of cracks with strong domination of normal compliance. Discovering such a significant number of naturally auxetic rocks is in contrast to the conventional viewpoint that occurrence of a negative Poisson ratio is an exotic fact that is mostly discussed for artificial structures.

Abstract:

By taking two different tile-drained agricultural basins with porous aquifers in the lowlands of northern Germany as examples, it is demonstrated with an integrated study approach that this type of basin responds similarly to an input as forested mountainous basins with dominant fractured rock aquifers in the central European highlands do. The control mechanism is local rise of pressure heads of aquifers starting with the infiltration process. It is shown that drain laterals in agricultural basins function like fractures and faults in those hard rock basins, i.e. as efficient drain pipe lines. This effect is amplified by hydraulic pressure transmission in the course of single input events, and additionally verified here with the help of artificial and environmental tracers. As a result stream flow is predominantly generated by exfiltrating groundwater. For this process drain laterals constitute fast hydraulic short cuts in the sense of preferential flow paths preferably in case that groundwater tables reach up to the level tile-drain networks.

Abstract:

This paper presents data on lithological composition, distribution, reservoir properties, geochemistry of organic matter and genesis of carbonate rocks of the Bazhenov formation within the central part of Western Siberia (the region of the Khantei hemianteclise). The following types of carbonates are distinguished: a) primary biogenic – shell rock interlayers and residues of coccolith; b) dia- and catagenetic – in varying degrees, recrystallized rocks with coccoliths, nodules and aporadiolarites; c) catagenetic – cracks healed with calcite in limestone of the foot of the Bazhenov formation. It was determined that the crystallization of the carbonate material of nodules took place in various conditions: in the bottom part of the sediments and in the later stages of diagenesis. The source of calcite for nodules was calcareous nanoplankton or bivalve shells. The carbonate content of the cuts decreases in the following sequence: Yuzhno-Yagunsky → Povkhovsky → Novortyagunsky → Druzhny areas, which are associated both with facial features and various physicochemical conditions of diagenesis and catagenesis. Transformation of organic matter increases in the northeast direction from South Yagunsky to Povkhovsky area, which is confirmed by molecular parameters of catagenesis. The carbonate rocks of the bottom part of the Bazhenov formation in the South Yagunsky area are similar in structure to the main oil-bearing reservoirs of the Salym and Krasnoleninsky fields.

Abstract:

Exploitation and processing of small stone blocks and tombolons has a major impact on profitability. It is pointed out that the natural stone needs to be rationally used in deposits. Resources of rock mass tend to be greatly increased due to the utilization of different sizes of blocks in deposits or quarries. This approach encourages the application of Lasky's relationship in the deposits of natural stone and quarries. Based on this relationship we can simply say that if the sizes of stone blocks and other stone products decrease arithmetically, then reserves increase geometrically or exponentially. On the presented examples, the utilization of the rock mass was analysed by the application of two different technologies of exploitation. Besides, if the exploitation of stone blocks of different sizes achieves high utilization of the rock mass, then exploitation of aggregates and fillers increases much more. It is necessary to emphasize the existence of the border area based on favourable discontinuity density and spatial discontinuity position. Decision should be made whether to apply I or II variant of the exploitation (making vertical and horizontal cuttings or separation of the blocks along natural discontinuities, or using slanting cuts). The example is shown and analysed as a two-dimensional problem.

Abstract:

An extensive polygonal fault system (PFS) within fine-grained Upper Cretaceous sediments beneath the Great Plains of North America has implications for geotechnical engineering. Geological well control, outcrop, and three-dimensional seismic data from southeast Saskatchewan exemplify the fault characteristics typically observed within the PFS. The deepest faults are sparse, offset a seismic reflection identified from the Niobrara Formation Govenlock member, and have vertical offsets <2 m. The deformation increases in fault density and vertical offset at shallower depths, reaching 6 faults/km2 with up to 30 m of vertical offset. Upper Cretaceous strata throughout the Great Plains area are at or near outcrop, and the extensive PFS faulting and weathering have weakened the rock. This faulting and weakness have been observed and attributed to other factors such as glacial erosion, overconsolidation, swelling bentonite beds, or landslides from toe erosion at topographic slopes. The PFS faulting should be recognized as an extensive process to be considered when undertaking geotechnical analysis on the Great Plains where underlying Upper Cretaceous rocks exist. Engineering implications include road cuts, dam impoundments, building foundations, and natural slumping.

Abstract:

WC-Co based tools are widely used in the field of coal and rock excavation because of their unique combination of strength, hardness, and resistance to abrasive wear. Conical pick is one of the coal cutting tools. The tip of the pick is made of WC-Co material. As coal and rock are heterogeneous elements, they pose various constraints during excavation. As a result the tools wear out during the process. Other parameters like cutting techniques, tool orientation, and environmental conditions also affect the tool significantly. The wearing phenomenon greatly reduces the service life of the tools and thereby cuts down the production rate. To prevent such wearing process, it is important to investigate the different wear mechanisms in WC-Co. Simultaneously, there has to be an ongoing endeavour for the development of better quality WC-Co. This paper focuses on different wear mechanisms in a conical pick which has been used in a continuous miner machine for coal cutting. The worn out surface has been observed by using FE-SEM (field emission scanning electron microscopy) and EDS (energy dispersive X-ray spectroscopy). The mechanisms, namely, coal/rock intermixing, cracking and crushing of WC grains, and adhesion of rock particles, have been predominantly investigated in this study. A little indication of corrosive decay in the WC grain has also been reported. The EDS has detected material concentration in a selected area or point of the worn-out surface. The spectrograph confirms the presence of coal/rock materials. Elements such as W, C, Ca, K, O, and Co have been mainly found in different concentrations at different positions.

Abstract:

Jalan Sungai Hitam in the Sandakan Peninsula traverses a flat to gently undulating terrain of low hills and ridges surrounded by broad alluvial flats. Recent slope cuts expose bluish to dark grey mudstones of the Garinono Formation containing pebble to boulder sized, angular to rounded, blocks of sandstone and other rock types. Slump-mud flows have occurred at most of the slope cuts; the failed materials characterized by desiccation cracks and fissures. Soil index properties, including consistency limits and grain size analyses, indicate that the mudstones have a medium to high swell potential. X-ray diffraction analyses show the clay minerals present to be kaolinite, illite and randomly interstratified illite-montmorillonite (a swelling clay mineral). The mudstones are thus sensitive to atmospheric wet-dry cycles with repeated swelling and shrinkage giving rise to the desiccation cracks and fissures, The cracks and fissures reduce the shear strength of the mudstones and allow for the infiltration of rainwater which initiates the slump-mud flows. It is concluded that earthworks in areas of the Garinono Formation in eastern Sabah need to consider the presence of swelling clay minerals; an occurrence that can be inferred from evaluating soil index properties.

Abstract:

We have measured the magnetic susceptibility of 5425 drill cuttings, coming from 20 oil wells distributed in eight fields of the Petroliferous Barinas-Apure Basin (Barinas, Venezuela), seeking evidence of magnetic anomalies associated with the presence of hydrocarbon deposits. The rock samples are located between the near earth’s surface and the basem*nt’s top (approximately 4000 m). In the magnetic susceptibility profiles, we observed high magnetic susceptibilities at the top of the sedimentary units corresponding to reservoir and source rocks of oil-producing wells, whereas in the case of nonproducing wells we observed low magnetic susceptibilities. A basic statistical analysis of the magnetic susceptibility measurements shows a significant difference between the mean values across producing and nonproducing wells at the correspondent oil-related formations, with a ratio of [Formula: see text] of producing to nonproducing wells. In the producing wells, we have found a relation between the magnitudes of the magnetic susceptibility and the age of the formation; the larger the magnetic susceptibility, the younger the geological stratum. The age and depth of the formations where the cuts were obtained exclude the presence of cultural (human origin) contamination of the samples, suggesting the evidence of authigenic origin of the magnetic minerals due to the reductive effect of hydrocarbons in rocks.

Abstract:

The Dog Bay Line separates different Silurian rock groups in northeast Newfoundland. West of the line, terrestrial volcanic rocks and sandstones (Botwood Group) overlie marine greywackes and conglomerates (Badger Group). East of the line, red sandstones overlie shallow marine shales and limestones (Indian Islands Group). Throughout Dog Bay, the line is marked by a disrupted zone of dark grey to black shales, volcanic rocks, and gabbros. Pervasive dextral, transpressive ductile deformation followed by successively more brittle extension with renewed dextral movements mark the northwest side of the line on the coast.The Dog Bay Line is traceable for 100 km and it is open-ended. Dextral offset is deduced to be many tens of kilometres. The line trends northeast, parallel to outcrop belts, and both the line and outcrop belts are curved eastward at the coast. The Mount Peyton Batholith, dated at 420 ± 8 Ma, apparently cuts the line.The Dog Bay Line occurs within the Dunnage Zone whose Cambrian–Ordovician rocks represent vestiges of the Iapetus Ocean. Northwest of the line, the Silurian rocks were deposited on Ordovician rocks already accreted to Laurentia. Southeast of the line, the Silurian rocks were deposited on Ordovician rocks already amalgamated with the continental Gander Zone. Timing of major movement and a Silurian marine to terrestrial depositional change recorded on both sides of the line agree within error with isotopic ages for the onset of plutonism, regional deformation, and metamorphism in central Newfoundland. The Dog Bay Line may mark the terminal Iapetus Ocean.

Abstract:

Purpose. Predicting the stress-strain state (SSS) of the rock mass in the zone of stope operations influence using the self-caving mining system and the calculation of the load-bearing capacity of mine workings support at the 10th Anniversary of Kazakhstan’s Independence mine. Methods. An engineering-geological data complex of the host rocks properties has been analyzed. Numerical modelling of the rock mass stress-strain state and the calculation of the load-bearing capacity of the support types used at the mine have been performed with the help of the RS2 software. This program, based on the Finite Element Method in a two-dimensional formulation, makes it possible to take into account a significant number of factors influencing the mass state. The Hoek-Brown model with its distinctive advantage of nonlinearity is used as a model for the mass behaviour. Findings. The values of the main stresses and load on the support have been obtained. According to the numerical analysis results of the rock mass stress-strain state at a depth of 900 m (horizon -480 m), the principal stresses are close to hydrosta-tic ones σ1 = σ2 = σz = 24.8 MPa. Predicting assessment of mine workings stability margin is performed before and after stope operations. Based on its results, it can be assumed that the stability margin of the mine workings driven in the stope zone is below the minimum permissible, therefore, caving and an increase in the load on the support are possible. Abutment pressure on mine workings support at a mining depth of 900 m (-480 m) has been calculated. The parameters of support in mine workings driven at the horizon -480 m have been calculated. Originality.The nature and peculiarities of patterns of the stress-strain state formation within the boundaries of various stope operations influence in blocks 20-28 at the horizon -480 m have been determined. The quantitative assessment of the values of loads on the support of haulage cross-cuts of the horizon mining is given. Practical implications. The research results can be used for creating a geomechanical model of the field and to design stable parameters of mine workings support. Keywords: stress-strain state, principal stresses, support, mine, ore, rock mass

Abstract:

Introduction. Due to a wide variety of placer dredging conditions, traditional methods of dredging parameters calculation do not always take into account all aspects of productive strata mining. It is first of all true for deep placers operation and mining with side cuts. Research aim is to improve the methods of calculating dredging parameters and the capacity of pilesupported bucket chain dredgers. Methodology. Existing methods of calculating dredging parameters and dredgers capacity do not take into account the applied mining method, stope type, and upper stope cave-in conditions. The indicated factors greatly influence the parameters of productive strata excavation and washery refuse disposal. Taking these ISSN 0536-1028 «Известия вузов. Горный журнал», № 3, 2020 13 factors into account makes it possible to forecast the indicators of the pile-support dredgers more accurately. Results. Investigation of some aspects of dredging trenches and side cuts has made it possible to establish the dependence of dredger maneuvering angle in pit face and capacity on cutting depth when mining massive productive strata; spoil dumps parameters dependence on the type of stoping; the interrelation between the daily capacity and the width of the front bank under various vertical distribution of rock. The indicated dependences allow to determine dredging parameters and indicators for particular conditions. Summary. The proposed approach, which calculates dredging parameters when using side cuts and when mining deep placers with non-uniform thickness of sands, makes it possible to calculate the chips size, buckets filling ratio and sand fragmentation ratio in a more substantiated way; it makes it possible to more effectively manage the process of sand mining, thus increasing the capacity of dredges.

Abstract:

In order to study characteristics of loads on a cutting drum of a continuous miner, a mathematic model of random loads on the drum is set up in the paper by means of defining probability distributions of three-direction loads, loads and their variations on a cutting drum are given by building a computer simulation program when it cuts pure coal, rock and hard parcel. Results show that swing resistance is the greatest, forward resistance is the second, axial resistance is the least; a cutting resistance torque increases with the increase of broken media strength; loads cut stone layer are much larger than pure coal; range of load change and load fluctuations are big as cutting hard parcel, these conclusions are correspond with the actual situation.

Abstract:

Abstract. Fault architecture and fracture network evolution (and resulting bulk hydraulic properties) are highly dependent on the mechanical properties of the rocks at the time the structures developed. This paper investigates the role of mechanical layering and pre-existing structures on the evolution of strike–slip faults and fracture networks. Detailed mapping of exceptionally well exposed fluvial–deltaic lithologies at Spireslack Surface Coal Mine, Scotland, reveals two phases of faulting with an initial sinistral and later dextral sense of shear with ongoing pre-faulting, syn-faulting, and post-faulting joint sets. We find fault zone internal structure depends on whether the fault is self-juxtaposing or cuts multiple lithologies, the presence of shale layers that promote bed-rotation and fault-core lens formation, and the orientation of joints and coal cleats at the time of faulting. During ongoing deformation, cementation of fractures is concentrated where the fracture network is most connected. This leads to the counter-intuitive result that the highest-fracture-density part of the network often has the lowest open fracture connectivity. To evaluate the final bulk hydraulic properties of a deformed rock mass, it is crucial to appreciate the relative timing of deformation events, concurrent or subsequent cementation, and the interlinked effects on overall network connectivity.

Abstract:

Conveyor belts transporting rock material are getting worn out mainly as a consequence of punctures and cuts caused by impacts of rock lumps in the belt loading zone. To enhance the operational durability of conveyor belts multidirectional actions intended to lower the dynamic load of belts, to increase the belt impact resistance and to monitor the belt condition are undertaken. Some significant improvements can be achieved by decreasing the material fall height, by implementation of transported material slides in transfer chutes and shock absorbing belt supports as well as by reducing rock lump sizes. To avoid extensive wear belt monitoring methods are being developed, so that belt defect numbers, sizes, and locations can be identified [1]. Implementation of monitoring prevents sudden belt tear and enables rational belt management by repairing and regenerating belts in the optimum time. Laboratory research programmes aim at identifying the relation of the dynamic stress and the belt fatigue strength [2,3]. Investigations of the effect of strength parameters and the structure of steel cord conveyor belts on their puncture resistance are carried out since many years [4,5,6,7]. High puncture resistance of a conveyor belt is one of the main assessment criteria of its operational durability. Research work on the impact of belt top cover thickness, cover rubber properties and type of belt crosswise reinforcements on the belt puncture resistance was undertaken in the Laboratory of Belt Transportation (LBT) of Wroclaw University of Technology [8].

Abstract:

The Acheloos river diversion project includes also works which improve the condition of the infrastructure network in the area. One of them was the improvement of a section at the Mouzaki - Arta national road. The road is developed through geological formations of the Pindos Zone. In the Argithea area, Karditsa County, it cuts through Cretaceous limestone bearing Calpionella. This formation develops high and steep slopes, over 50 m high. It consists of thin to medium bedded limestone, showing locally chert intercalations, and gradational transition to siliceous limestone. Thin silt or clay layers separate bedding. The formations is strongly folded and intensively jointed. The initial design proposed the construction of a slope with H:V relationship of 1:4 and benches every 20 m. The designed geometry was during and soon after excavation destroyed, due to sliding of rock particles. A new geometry was developed possessing a more stable state of dynamic equilibrium. Our task is to investigate and simulate the behavior of this formation. Based on data from both laboratory analysis and literature we ascribed the limestone formation values for its geotechnical properties. Using these values we estimate the values for the Safety Factor for the geometrical features of the slope. We control the stability of the slope using both rock mechanics and soil mechanic methods. The results point that rock formations, like the Cretaceous limestone which exhibit variation in their composition, and high contrast between the geotechnical characteristics values of the composing elements, may be considered as a material with soil properties. The Safety Factor calculation using these assumptions for the above mentioned slope, resulted a geometry close to the one developed. Therefore we conclude that such rock material and formations may successfully be simulated as materials with soil geotechnical behavior.